Engine Control System - Tests W/codes - DTC p0453-p0656 GMC Savana I

MODEL IDENTIFICATION

Vehicle model is identified by fourth character (cars), or fifth character (trucks) of Vehicle Identification Number (VIN). VIN is stamped on metal pad on top of left end of instrument panel, near windshield. See MODEL IDENTIFICATION (CARS) table, or MODEL IDENTIFICATION (TRUCKS) table under MODEL IDENTIFICATION in INTRODUCTION article.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Circuit Description

Tank pressure sensor is a 3-wire gauge sensor that responds to changes in pressure in fuel tank. Sensor measures the difference between air pressure (or vacuum) in fuel tank and ambient/outside air pressure. When air pressure in fuel tank is equal to outside air pressure (fuel cap removed), output of sensor will measure 1.3-1.7 volts. DTC will set if signal voltage is greater than 4.98 volts for greater than 3 seconds.

Diagnostic Procedures

1. Connect scan tool. Remove fuel filler cap. Turn ignition on, engine off. Using scan tool, monitor fuel tank pressure voltage. If pressure voltage is 1.3-1.7 volts, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656__diagnostic-aids) . If pressure voltage is not 1.3-1.7 volts, go to next step.
2. Locate and disconnect 3-way instrument panel-body and engine-body harness connector (located behind left kick panel). If tank pressure voltage is now less than 0.2 volt, go to next step. If tank pressure voltage is not less than 0.2 volt, check circuit between connector and PCM for short to battery voltage. Repair as necessary. If circuit is okay, replace PCM.
3. Check voltage between 5-volt reference and signal circuit at harness connector terminals. If voltage reading is greater than 4.2 volts, go to next step. If voltage reading is not greater than 4.2 volts, check continuity of signal circuit between harness connector and PCM connector. Repair as necessary. If circuit is okay, replace PCM.
4. Reconnect 3-way harness connectors. Lower fuel tank and disconnect fuel tank pressure sensor harness connector. If fuel tank pressure sensor voltage is less than 0.2 volt, go to next step. If fuel tank pressure sensor voltage is not less than 0.2 volt, check circuit to PCM for short to battery voltage. Repair as necessary.
5. Check voltage between fuel tank pressure sensor harness connector terminals "A" and "C". If voltage reading is greater than 4.2 volts, replace fuel tank pressure sensor. If voltage reading is not greater than 4.2 volts, check for open or short to battery voltage in signal circuit. Repair as necessary.

Diagnostic Aids

An intermittent open in the signal or 5-volt reference circuit or connectors will set DTC. Wiggle harnesses and connectors while monitoring tank pressure voltage. Review malfunction history data and attempt to reproduce the condition and fault.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors fuel tank pressure sensor signal to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. Fuel tank pressure sensor measures the difference between air pressure (or vacuum) in the tank and the outside air pressure. PCM applies 5-volt reference and ground to the sensor. Sensor will return a signal voltage between 0.2-4.0 volts. If PCM detects fuel tank pressure sensor voltage greater than 4.9 volts and for longer than 25 seconds, DTC will set.

Conditions for setting DTC

1. Ignition on.
2. Fuel tank pressure sensor signal is greater than 4.9 volt for greater than 25 seconds.
3. Conditions present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Monitor fuel tank pressure sensor voltage on scan tool. If scan tool reading is greater than 3.0 volts, go to next step. If scan tool reading is not greater 3.0 volts, go to step 4 .
3. Turn ignition off. Disconnect fuel tank pressure sensor harness connector. Turn ignition on, engine off. If scan tool shows 0.2 volt or less, go to step 5 . If scan tool reading is not 0.2 volt or less, go to step 6 .
4. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. If scan tool displays fuel tank pressure value at 3.0 volts or greater, go to next step. If fuel tank pressure value is not 3.0 volts or greater, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Using a test light connected to battery voltage, probe fuel tank pressure sensor ground circuit terminal. If test light illuminates, go to step 7 . If test light does not illuminate, go to step 9 .
6. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 10 .
7. Check voltage between ground and fuel tank pressure sensor 5-volt reference circuit. If voltage reading is 5 volts, go to step 11 . If voltage reading is not 5 volts, go to next step.
8. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure sensor 5-volt reference circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 10 .
9. Check for open or poor connection in fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
10. Check for poor connection at PCM harness connector. Repair or replace as necessary. After repairs, go to step 12 .
11. Check for poor terminal connections at fuel tank pressure sensor connector. Repair or replace as necessary. After repairs, go to next step.
12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
13. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at PCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors fuel tank pressure sensor signal to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. Fuel tank pressure sensor measures the difference between air pressure (or vacuum) in the tank and the outside air pressure. PCM applies 5-volt reference and ground to the sensor. Sensor will return a signal voltage between 0.1-4.9 volts. If PCM detects a fuel tank pressure sensor signal that is excessively low, DTC will set.

Conditions for setting DTC

1. Ignition on.
2. Fuel tank pressure sensor signal is greater than 4.8 volt.
3. Conditions present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Monitor fuel tank pressure sensor voltage on scan tool. If scan tool reading is greater than 4.7 volts, go to step 4 . If scan tool reading is not greater 4.7 volts, go to next step.
3. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Disconnect fuel tank pressure sensor connector. Using scan tool observe fuel tank pressure sensor voltage. If scan tool display reads about zero volts, go to step 6 . If scan tool display is not about zero volts, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to step 10 .
6. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure ground circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
7. Check for open in fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for poor terminal connections at fuel tank pressure sensor connector. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
9. Replace fuel tank pressure sensor. After replacing sensor, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
12. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at PCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors fuel tank pressure sensor signal to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. Fuel tank pressure sensor measures the difference between air pressure (or vacuum) in the tank and the outside air pressure. PCM applies 5-volt reference and ground to the sensor. Sensor will return a signal voltage between 0.1-4.9 volts. If PCM detects a fuel tank pressure sensor signal that is excessively low, DTC will set.

DTC will set if fuel tank pressure sensor signal is greater than 4.9 volt and condition is present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, monitor fuel tank pressure sensor voltage. If scan tool reading is greater than 4.7 volts, go to step 4 . If scan tool reading is not greater 4.7 volts, go to next step.
3. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Disconnect fuel tank pressure sensor connector. Using scan tool observe fuel tank pressure sensor voltage. If scan tool display reads about zero volts, go to step 6 . If scan tool display is not about zero volts, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to step 10 .
6. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure ground circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
7. Check for open in fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for poor terminal connections at fuel tank pressure sensor connector. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
9. Replace fuel tank pressure sensor. After replacing sensor, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
12. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at PCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (3.8L "C", "F", "G", "H" & "W" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors fuel tank pressure sensor signal to detect vacuum decay and excess vacuum during the enhanced EVAP diagnostic. Fuel tank pressure sensor measures the difference between air pressure (or vacuum) in the tank and the outside air pressure. PCM applies 5-volt reference and ground to the sensor. Sensor will return a signal voltage between 0.1-4.9 volts. If PCM detects a fuel tank pressure sensor signal that is excessively low, DTC will set.

Conditions for setting DTC

1. Ignition on.
2. Fuel tank pressure sensor signal is greater than 4.8 volts
3. Conditions present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Monitor fuel tank pressure sensor voltage on scan tool. If scan tool reading is greater than 4.7 volts, go to step 4 . If scan tool reading is not greater 4.7 volts, go to next step.
3. Turn ignition on, engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Disconnect fuel tank pressure sensor connector. Using scan tool observe fuel tank pressure sensor voltage. If scan tool display reads about zero volts, go to step 6 . If scan tool display is not about zero volts, go to next step.
5. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to step 10 .
6. Turn ignition off. Disconnect PCM harness connector. Check fuel tank pressure ground circuit for poor terminal connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
7. Check for open in fuel tank pressure sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for poor terminal connections at fuel tank pressure sensor connector. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
9. Replace fuel tank pressure sensor. After replacing sensor, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
12. Check for additional DTCs set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at PCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

EVAP tank pressure sensor responds to changes in resistance based upon fuel tank pressure (or vacuum). Vacuum is considered negative pressure.

PCM provides a 5-volt reference and ground signal to sensor. Signal varies between ground and 5 volts as fuel tank pressure varies. As pressure decreases, voltage increases and vice-versa. PCM uses EVAP fuel tank pressure sensor values as an indicator of EVAP system efficiency.

DTC will set when EVAP fuel tank pressure sensor signal goes high when signal line is shorted to voltage, EVAP fuel tank pressure sensor is shorted internally or EVAP fuel tank pressure sensor reading has been 4.8 volts or greater.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, monitor EVAP fuel tank pressure sensor display. If scan tool reading is greater than 4.8 volts, go to next step. If scan tool reading is not greater than 4.8 volts, fault is not present. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect EVAP fuel tank pressure sensor harness connector. If scan tool reading is less than 0.22 volt, go to next step. If scan tool reading is not less than 0.22 volts, go to step 5 .
4. Using DVOM, check voltage between ground and 5-volt reference circuit at EVAP fuel tank pressure sensor connector. If voltage reading is greater than 5.5 volts, go to step 7 . If voltage reading is not greater than 5.5 volts, go to step 8 .
5. Using DVOM, check voltage between ground and sensor signal circuit at EVAP fuel tank pressure sensor connector. If voltage reading is greater than 0.5 volt, go to next step. If voltage reading is not greater than 0.5 volt, go to step 10 .
6. Repair short to voltage on EVAP fuel tank pressure sensor signal circuit.
7. Repair short to voltage on 5-volt reference circuit.
8. Check terminal contact at EVAP fuel tank pressure sensor. Repair as necessary. If terminal contact is okay, go to next step.
9. Replace EVAP fuel tank pressure sensor.
10. Check terminal contact at PCM harness connector. Repair as necessary. If terminal contact is okay, go to next step.
11. Replace PCM. Program replacement PCM using required equipment.

EVAP fuel tank pressure sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

EVAP tank pressure sensor responds to changes in resistance based upon fuel tank pressure (or vacuum). Vacuum is considered negative pressure.

PCM provides a 5-volt reference and ground signal to sensor. Signal varies between ground and 5 volts as fuel tank pressure varies. As pressure decreases, voltage increases and vice-versa. PCM uses fuel tank pressure sensor values as an indicator of EVAP system efficiency.

DTC will set when ignition switch in RUN position, fuel tank pressure sensor reading is greater than 4.9 volts and all conditions present for greater than 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, monitor FAILED THIS IGNITION option under DTC INFO option. If scan tool indicates that DTC P1635 or P1639 failed in this ignition cycle, diagnose DTC P1635 or P1639. If scan tool does not indicate that DTC P1635 or P1639 failed in this ignition cycle, go to next step.
3. Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool, monitor fuel tank pressure sensor voltage. If sensor voltage is greater than 4.3 volts, go to step 5 . If sensor voltage is less than 4.3 volts, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC, and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, and then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Turn ignition off for 15 seconds. Disconnect fuel tank pressure sensor connector at fuel tank. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure sensor voltage. If pressure sensor voltage is less than one volt, go to next step. If pressure sensor voltage is greater than one volt, go to step 7 .
6. Using a test light connected to battery voltage, probe fuel tank pressure sensor ground circuit. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 8 .
7. Using DVOM connected to ground, probe fuel tank pressure sensor signal circuit. If pressure sensor voltage is near zero volts, go to step 14 . If pressure sensor voltage is not near zero volts, go to step 9 .
8. Turn ignition off. Disconnect PCM harness connector. Using DVOM, measure resistance of fuel tank pressure sensor ground circuit between fuel tank pressure sensor harness connector and PCM harness connector. If resistance is 0-5 ohms, go to step 12 . If resistance is not 0-5 ohms, go to step 10 .
9. Repair short to voltage in fuel tank pressure sensor signal circuit. After repairs, go to step 15 .
10. Repair open or high resistance in fuel tank pressure sensor ground circuit. After repairs, go to step 15 .
11. Check for poor connection at fuel tank pressure sensor. Repair as necessary. After repairs, go to step 15 . If connection is okay, go to step 13 .
12. Check for poor connection at PCM. Repair as necessary. After repairs, go to step 15 . If connection is okay, go to step 14 .
13. Replace fuel tank pressure sensor. After repairs, go to step 15 .
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
16. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel tank pressure sensor responds to changes in fuel tank pressure (or vacuum). Vacuum is considered negative pressure. This information is used in order to detect vacuum decay or an excessive vacuum during EVAP diagnostic routine.

Fuel tank pressure sensor signal voltage to VCM varies from a minimum of about 0.1 volt with pressure in fuel tank to greater than 4.0 volts with high vacuum in fuel tank.

DTC will set when fuel tank pressure sensor voltage is greater than 4.98 volts for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, monitor fuel tank pressure sensor reading. If fuel tank pressure sensor value is within -1.0 to 1.0 in. H2O, go to next step. If fuel tank pressure sensor value is not within -1.0 to 1.0 in. H2O, go to step 4 .
3. DTC is intermittent. Check for additional DTCs set. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel tank pressure sensor harness connector. Turn ignition on, engine off. Using DVOM, check voltage between fuel tank pressure sensor harness connector signal and ground circuits. If voltage reading is less than 0.22 volt, go to next step. If voltage reading is not less than 0.22 volt, go to step 6 .
5. Check voltage between 5-volt reference circuit and sensor ground circuit at fuel tank pressure sensor harness connector. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not about 5 volts, go to step 7 .
6. Check voltage between fuel tank pressure sensor signal and ground circuits. If voltage reading is greater than 0.5 volt, go to step 8 . If voltage reading is not greater than 0.5 volt, go to step 10 .
7. Check for short to voltage in 5-volt reference circuit. If circuit is shorted, go to step 11 . If circuit is okay, go to step 9 .
8. Check for short to voltage in fuel tank pressure sensor signal circuit. If circuit is shorted, go to step 11 . If circuit is okay, go to step 12 .
9. Check fuel tank pressure sensor for water intrusion, backed out terminal, improper terminal mating or poor terminal-to-wire connections. If problem is found, go to step 11 . If sensor connections are okay, go to step 12 .
10. Check terminal contact at VCM. If problem is found, go to next step. If terminal contact is okay, go to step 13 .
11. Repair circuit as necessary. After repairs, go to step 14 .
12. Replace fuel tank pressure sensor. After replacing sensor, go to step 14 .
13. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at VCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel tank pressure sensor responds to changes in fuel tank pressure (or vacuum). Vacuum is considered negative pressure. This information is used in order to detect vacuum decay or an excessive vacuum during EVAP diagnostic routine.

Fuel tank pressure sensor signal voltage to VCM varies from a minimum of about 0.1 volt with pressure in fuel tank to greater than 4.0 volts with high vacuum in fuel tank.

DTC will set when fuel tank pressure sensor voltage is greater than 4.98 volts for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, monitor fuel tank pressure sensor reading. If fuel tank pressure sensor value is within -1.0 to 1.0 in. H2O, go to next step. If fuel tank pressure sensor value is not within -1.0 to 1.0 in. H2O, go to step 4 .
3. DTC is intermittent. Check for additional DTCs set. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel tank pressure sensor harness connector. Turn ignition on, engine off. Using DVOM, check voltage between fuel tank pressure sensor harness connector signal and ground circuits. If voltage reading is less than 0.22 volt, go to next step. If voltage reading is not less than 0.22 volt, go to step 6 .
5. Check voltage between 5-volt reference circuit and sensor ground circuit at fuel tank pressure sensor harness connector. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not about 5 volts, go to step 7 .
6. Check voltage between fuel tank pressure sensor signal and ground circuits. If voltage reading is greater than 0.5 volt, go to step 8 . If voltage reading is not greater than 0.5 volt, go to step 10 .
7. Check for short to voltage in 5-volt reference circuit. If circuit is shorted, go to step 11 . If circuit is okay, go to step 9 .
8. Check for short to voltage in fuel tank pressure sensor signal circuit. If circuit is shorted, go to step 11 . If circuit is okay, go to step 12 .
9. Check fuel tank pressure sensor for water intrusion, backed out terminal, improper terminal mating or poor terminal-to-wire connections. If problem is found, go to step 11 . If sensor connections are okay, go to step 12 .
10. Check terminal contact at VCM. If problem is found, go to next step. If terminal contact is okay, go to step 13 .
11. Repair circuit as necessary. After repairs, go to step 13 .
12. Replace fuel tank pressure sensor. After replacing sensor, go to step 14 .
13. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Check for additional DTCs. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, system is okay.

Check for damaged harness or poor connection at VCM or fuel tank pressure sensor.

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (5.7L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

EVAP tank pressure sensor responds to changes in resistance based upon fuel tank pressure (or vacuum). Vacuum is considered negative pressure.

PCM provides a 5-volt reference and ground signal to sensor. Signal varies between ground and 5 volts as fuel tank pressure varies. As pressure decreases, voltage increases and vice-versa. PCM uses EVAP fuel tank pressure sensor values as an indicator of EVAP system efficiency.

DTC will set when EVAP fuel tank pressure sensor signal goes high when signal line is shorted to voltage, EVAP fuel tank pressure sensor is shorted internally or EVAP fuel tank pressure sensor reading has been greater than 4.9 volts.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION option under DTC INFO option. If scan tool indicates that DTC P1639 failed this ignition cycle, diagnose DTC P1639. If scan tool does not indicate that DTC P1639 failed in this ignition cycle, go to next step.
3. Turn ignition on, engine off. Using scan tool, monitor fuel tank pressure sensor voltage. If voltage is greater than 4.8 volts, go to step 5 . If voltage is not greater than 4.8 volts, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter DTC P0453. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect fuel tank pressure sensor at body pass-through connector. Using scan tool, monitor fuel tank pressure sensor voltage. If voltage is less than one volt, go to next step. If voltage is not less than one volt, go to step 12 .
6. Using a test light connected to battery positive, probe ground circuit at fuel tank pressure sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
7. Measure voltage between battery ground and 5-volt reference at fuel tank pressure sensor body pass-through connector. If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to step 20 .
8. Check for faulty connections at body pass-through connector. Repair as necessary. After repairs, go to step 21 . If connections are okay, go to next step.
9. Turn ignition off. Reconnect body pass-through connector. Lower fuel tank. Disconnect fuel tank pressure sensor connector. Turn ignition on, with engine off. Using scan tool, monitor fuel tank pressure sensor voltage. If voltage is less than one volt, go to next step. If voltage is not less than one volt, go to step 15 .
10. Using a test light connected to battery positive, probe ground circuit at fuel tank pressure sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 16 .
11. Measure voltage between battery ground and 5-volt reference circuit at fuel tank pressure sensor harness connector. If voltage is about 5 volts, go to step 18 . If voltage is not about 5 volts, go to step 17 .
12. Check signal circuit for short to voltage or short to 5-volt reference circuit between body pass-through connector and PCM. Repair as necessary. After repairs, go to step 21 . If circuit is okay, go to step 14 .
13. Measure resistance of fuel tank pressure sensor ground circuit between body pass-through connector and PCM. Repair circuit if resistance is greater than 2 ohms. After repairs, go to step 21 . If circuit is okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 21 .
15. Repair signal circuit for short to ground. After repairs, go to step 21 .
16. Repair open ground circuit. After repairs, go to step 21 .
17. Repair 5-volt reference circuit for short to voltage. After repairs, go to step 21 .
18. Check for faulty ground circuit terminal connection at body pass-through connector. Repair as necessary. After repairs, go to step 21 . If connection is okay, go to next step.
19. Replace fuel tank pressure sensor. After repairs, go to step 21 .
20. Repair 5-volt reference circuit for short to voltage. After repairs, go to next step.
21. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
22. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

EVAP fuel tank pressure sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).

DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

EVAP tank pressure sensor responds to changes in resistance based upon fuel tank pressure (or vacuum). Vacuum is considered negative pressure.

PCM provides a 5-volt reference and ground signal to sensor. Signal varies between ground and 5 volts as fuel tank pressure varies. As pressure decreases, voltage increases and vice-versa. PCM uses fuel tank pressure sensor values as an indicator of EVAP system efficiency.

DTC will set when engine is running, fuel tank pressure sensor voltage is greater than 4.90 volts, and all conditions are present for more than 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, monitor FAILED THIS IGNITION option under DTC INFO option. If scan tool indicates that DTC P1639 failed in this ignition cycle, diagnose DTC P1639. If scan tool does not indicate that DTC P1639 failed in this ignition cycle, go to next step.
3. Using scan tool, monitor fuel tank pressure sensor voltage. If voltage is greater than 4.3 volts, go to step 5 . If voltage is not greater than 4.3 volts, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this DTC to run. Using scan tool, select DTC option, SPECIFIC DTC option, then enter DTC P0453. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Remove left rear wheelhouse panel. Disconnect fuel tank pressure sensor harness connector. Using scan tool, monitor fuel tank pressure sensor voltage. If voltage is less than one volt, go to next step. If voltage is not less than one volt, go to step 7 .
6. Using test light connected to battery positive, probe ground circuit at fuel tank pressure sensor harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to step 10 .
7. Check fuel tank pressure sensor signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 12 .
8. Measure voltage between ground and 5-volt reference circuit at fuel tank pressure sensor harness connector. If voltage is near 5 volts, go to next step. If voltage is not near 5 volts, go to step 15 .
9. Check for plugged or leaking vacuum supply to fuel tank pressure sensor. If vacuum supply is okay, go to step 13 . If vacuum supply is not okay, go to step 14 .
10. Check fuel tank pressure sensor ground circuit for poor connection at PCM harness connector. Repair as necessary. After repairs, go to step 16 . If connection is okay, go to next step.
11. Measure resistance of fuel tank pressure sensor ground circuit. If resistance is greater than 5 ohms, repair circuit as necessary. After repairs, go to step 16 . If resistance is not greater than 5 ohms, go to next step.
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 16 .
13. Replace fuel tank pressure sensor. After repairs, go to step 16 .
14. Repair faulty vacuum supply. After repairs, go to step 16 .
15. Repair 5-volt reference circuit for a short to voltage. After repairs, go to next step.
16. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0455: EVAP SYSTEM-LARGE LEAK DETECTED (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

During specific operating conditions, ECM performs various tests on Evaporative Emission (EVAP) system. System tests consist of the following series of events.

After ensuring that EVAP purge solenoid valve duty cycle has dropped to zero percent, indicating that valve is closed, ECM commands EVAP canister vent valve closed, sealing system. ECM monitors accumulation of vapor pressure within fuel tank via fuel tank pressure sensor. EVAP test is aborted if vapor pressure is too high. If any vapor pressure is measured, it will be used later to compensate a pressure reading during small leak detection test. If a vacuum is measured which exceeds a calculated limit during vapor accumulation, this DTC will set. EVAP canister purge solenoid valve is then opened. Simultaneously, vent is opened.

If vapor pressure does not bleed off or bleeds off too slowly, this DTC is set. Once EVAP purge solenoid valve reaches its desired position for remainder of diagnostic test, vent valve will be closed again. This causes vacuum to be applied to entire EVAP system. ECM monitors vacuum level within system. If desired vacuum level cannot be achieved, or if vacuum level is reached but took too much time, DTC P0455 will set. Once desired vacuum level is reached, purge solenoid is closed, sealing system. ECM continues to monitor fuel tank pressure sensor signal, measuring rate of vacuum decay. If system holds vacuum, vent valve is opened and test is completed. In addition to system tests, ECM monitors circuit integrity of purge solenoid (DTC P0443), vent valve (DTC P0446) and fuel tank pressure sensor (DTC P0450).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If DTCs P0443 or P0446 are also set, go to applicable DTC. If DTCs P0443 or P0446 are not set, go to next step.
3. Inspect EVAP system for disconnected, kinked or deteriorated hoses and lines. Check for loose hose connections or missing or loose fuel cap. Inspect for obvious damage to any system component. Repair components as necessary. After repairs, go to step 23 . If components are okay, go to next step.
4. Disconnect manifold vacuum source hose at purge valve. Connect a vacuum gauge to manifold vacuum source hose. EVAP Pressure/Purge Cartridge (J-41413) can be used for this purpose, if necessary. Operate engine at greater than 2000 RPM. Observe source vacuum level. If vacuum gauge indicates 15 in. Hg, go to next step. If vacuum gauge does not indicate 15 in. Hg, go to step 16 .
5. Turn ignition off. Remove fuel cap. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure. If fuel tank pressure is -1 to 1 in. H2O, go to next step. If fuel tank pressure is not -1 to 1 in. H2O, go to DTC P0450.
6. Zero gauges on EVAP Pressure/Purge Cartridge (J-41413) prior to installation. Connect pressure/purge cartridge to EVAP service port. Reinstall fuel cap. Plug EVAP vent hose or disconnect vent hose from vent valve and plug hose. Attempt to pressurize EVAP system using pressure/purge cart. Monitor pressure using gauge on EVAP pressure/purge cartridge. If pressure reading is 15 in. H2O, go to next step. If pressure reading is not 15 in. H2O, go to step 10 .
7. Maintain EVAP system pressure at 15 in. H2O. Observe fuel tank pressure on scan tool. If fuel tank pressure is at or greater than 11 in. H2O, go to next step. If fuel tank pressure is not at or greater than 11 in. H2O, go to DTC P0450.
8. Switch rotary switch on pressure/purge cart to HOLD and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to step 10 . If pressure does not drop to less than 10 in. H2O within 2 minutes, go to next step.
9. Unplug EVAP vent hose and/or reconnect vent hose at vent valve. Disconnect ECM harness connector located in engine compartment relay center. Remove main relay. Using fused jumper, connect between battery circuit and switched battery feed circuit at relay harness connector. Using another fused jumper, ground EVAP vent valve control circuit at ECM harness connector. This closes vent valve. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to step 18 . If pressure does not drop to less than 10 in. H2O within 2 minutes, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
10. Disconnect fuel tank to EVAP canister vapor hose at canister and plug port on canister. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to next step. If pressure does not drop to less than 10 in. H2O within 2 minutes, go to step 14 .
11. Disconnect purge valve to EVAP canister vapor hose at purge valve and plug hose. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to next step. If pressure does not drop to less than 10 in. H2O within 2 minutes, go to step 17 .
12. Disconnect vent hose at EVAP canister and plug port on canister. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to next step. If pressure does not drop to less than 10 in. H2O within 2 minutes, go to step 20 .
13. Disconnect purge hose at EVAP canister and plug hose. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to step 21 . If pressure does not drop to less than 10 in. H2O within 2 minutes, go to step 19 .
14. Reconnect fuel tank vapor hose at EVAP canister. Disconnect fuel tank vapor hose at fuel tank and plug hose. Restore system pressure to 15 in. H2O using pressure/purge cartridge. Switch rotary switch to HOLD position and observe EVAP pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to step 22 . If pressure does not drop to less than 10 in. H2O within 2 minutes, go to next step.
15. Reconnect fuel tank vapor hose at fuel tank. With pressure/purge cartridge connected to EVAP service port, continuously attempt to pressurize EVAP system by leaving cart control knob in PRESSURIZE position. Using Ultrasonic Leak Detector (J-41416), locate fuel tank system leaks. Check fuel tank, tank seams, fuel cap, fill pipe, sending unit, sending unit-to-tank seal, or fuel tank pressure sensor. Repair as necessary. After repairs, go to step 23 .
16. Check for damaged vacuum source hose, blocked or restricted manifold vacuum port or low engine vacuum. Repair as necessary. After repairs, go to step 23 .
17. Replace purge valve. After replacing valve, go to step 23 .
18. Replace vent valve. After replacing valve, go to step 23 .
19. Replace canister. After replacing canister, go to step 23 .
20. Replace vent hose. After replacing hose, go to step 23 .
21. Replace purge hose (valve-to-canister). After replacing hose, go to step 23 .
22. Replace vapor hose (tank-to-canister). After replacing hose, go to next step.
23. Ensure that vent valve is on (closed). Pressurize EVAP system to 15 in. H2O using pressure/purge cartridge. Monitor pressure using gauge on EVAP pressure/purge cartridge. Switch rotary switch on cart to HOLD position and observe pressure gauge. If pressure drops to less than 10 in. H2O within 2 minutes, go to step 6 . If pressure does not drop to less than 10 in. H2O within 2 minutes, go to next step.
24. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0455 is set, repeat step 2 . If DTC P0455 is not set, go to next step.
25. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

Check for faulty fuel cap, damaged, pinched or blocked EVAP purge line, damaged EVAP vent hose, or pinched or blocked fuel tank vapor line. Check for EVAP canister purge valve or vent valve malfunction (non-electrical). Check for damaged EVAP canister. Inspect for leaking fuel sender assembly "O" ring, or leaking fuel tank or fuel filler neck.

If no apparent cause of large leak can be found, vehicle may have been left running during refueling. By coincidence, proper conditions may have been met to set DTC during time fuel cap was off or loose.

DTC P0460: FUEL LEVEL SENSOR CIRCUIT (2.4L "N" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Powertrain Control Module (PCM) uses fuel level input from the instrument panel cluster to calculate expected vapor pressures within fuel system. Vapor pressure varies as fuel level changes.

Conditions for setting this DTC are as follows

1. Fuel level has not changed greater than 1.6 percent (4 counts) in 120 miles.
2. DTC P1601 or P1610 is set and vehicle has been driven for greater than 120 miles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Check if DTC U1016 or U1064 is also set. If DTC U1016 or U1064 is set, diagnose affected DTCs first. If no other DTCs are set, go to next step.
3. Diagnose instrument cluster. After diagnosing instrument cluster, go to next step.
4. Verify repairs by viewing scan tool fuel level data. If fuel level data reflects the correct amount of fuel in the tank, go to next step. If fuel level data does not reflect correct amount of fuel in fuel tank, repeat step 2 .
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
6. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, system is okay.

When DTC P0460 is set and an EVAP system DTC is also set, the EVAP DTC cannot be considered valid until DTC P0460 is repaired and cleared.

DTC P0460: FUEL LEVEL SENSOR CIRCUIT (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

As fuel level decreases, sending unit resistance increases. As fuel level increases, sending unit resistance decreases. Sending unit range of resistance is about 43 ohms with full tank to about 272 ohms with empty tank. DTC will set if ECM senses fuel level sensor voltage is greater than 4.8 volts, or less than 0.1 volt for one second.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Raise and support vehicle. Disconnect fuel pump harness connector. Using a test light connected to battery positive, probe both ground circuits from ECM at fuel level sensor harness connector. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 8 .
3. Turn ignition on. Measure voltage between ground and fuel level input circuit at fuel level sensor harness connector (ECM side). If battery voltage is present, go to next step. If battery voltage is not present, go to step 7 .
4. Check for faulty harness connections. If a problem is found, go to step 12 . If connections are okay, go to next step.
5. Check harness between harness connector and fuel pump for opens or shorts. If a problem is found, go to next step. If harness is okay, go to step 7 .
6. Repair open or short in harness as necessary. After repairs, go to step 13 .
7. Replace fuel level sensor. After repairs, go to step 13 .
8. Repair open in ground circuit. After repairs, go to step 13 .
9. Check fuel level input circuit for a short to ground. If a problem is found, go to next step. If circuit is okay, go to step 11 .
10. Repair open or short to ground in fuel level input circuit. After repairs, go to step 13 .
11. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code that is currently on vehicle. After repairs, go to step 13 .
12. Repair or replace terminals as necessary. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
14. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

See FUEL LEVEL SENSOR SPECIFICATIONS table.

FUEL LEVEL SENSOR SPECIFICATIONS

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The PCM monitors resistance of fuel level sensor (tank sender) to calculate the amount of fuel in fuel tank, and provides voltage to tank sender through a resistor network and a return to PCM ground. If fuel level changes by less than 2 percent while driving 30 miles, DTC will set.

Using scan tool, monitor fuel level voltage while rocking vehicle back and forth. Voltage will fluctuate with a normal operating system. If voltage does not fluctuate, check for mechanically stuck fuel sender assembly or faulty fuel sender float.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (2.2L "J" BODY & "S" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses fuel level input in order to calculate expected vapor pressure within the fuel system. Vapor pressure vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level to determine is fuel system is too high or too low to be able to accurately detect EVAP system faults.

DTC will set when fuel level input has not changed more than 1.6 percent in 120 miles, or DTC U1016 is set and vehicle has been driven more than 120 miles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, check for DTCs. If DTC U1016 is set, go to DTC U1016 and diagnose first. If DTC U1016 is not set, go to next step.
3. Check IPC for DTCs. See SELF-DIAGNOSTIC SYSTEM in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Repair as necessary. After repairs, go to next step.
4. Verify repairs by monitoring fuel level data with scan tool. If scan tool data matches amount of fuel in tank, go to next step. If scan tool data does not match fuel level in tank, go to step 2 .
5. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
6. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

If DTC P0461 is set along with an EVAP system DTC, the EVAP DTC can not be considered valid until DTC P0461 is repaired and cleared. A DTC U1016 set along with A DTC P0461 indicates PCM was unable to obtain updated fuel level information due to a serial data communication problem with Instrument Panel Cluster (IPC). DTC U1016 must be diagnosed before DTC P0461, since problem may only be a serial communication problem and vehicle was driven more than 120 miles before brought in for service.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses fuel level input in order to calculate expected vapor pressure within the fuel system. Vapor pressure vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level to determine is fuel system is too high or too low to be able to accurately detect EVAP system faults.

DTC will set when fuel level input has not changed more than 1.6 percent in 120 miles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, check for DTCs. If DTCs P0462 or P0463 are set, diagnose these DTCs first. If DTCs P0462 and P0463 are not set, go to next step.
3. Turn ignition off. Disconnect fuel level sensor harness connector. Turn ignition on, with engine off. Using scan tool, monitor fuel level. If value is 100 percent, go to next step. If value is not 100 percent, go to step 5 .
4. Using a fused jumper wire, jumper fuel level sensor signal and ground circuits together at harness connector. Using scan tool, monitor fuel level sensor. If value is zero percent, go to step 10 . If value is not zero percent, go to step 6 .
5. Check fuel level sensor circuit for a short to ground. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 9 .
6. Using a test light connected to battery positive, probe ground circuit at fuel level sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
7. Check fuel level sensor signal circuit for an open or poor connection. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 9 .
8. Check fuel level sensor ground circuit at PCM harness connector for an open or poor connection. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 12 .
10. Check for faulty fuel level sensor harness connection. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to next step.
11. Replace fuel level sensor. After repairs, go to next step.
12. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
13. Using scan tool, display CAPTURE and REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

For any test that requires probing ECM or component harness connectors, use Connector Test Adapter Kit (J-35616-A). This will prevent damage to harness connector terminals. Check for the following conditions

Check for poor connections at ECM or at component. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.

Check for misrouted wiring harness. Inspect harness to ensure that it is not routed too close to high voltage wires (spark plug wires) or too close to high current devices (generator, motors, solenoids).

Check for damaged wiring harness. If harness appears to be okay, observe scan tool while moving related connectors and wiring harnesses. A change in scan tool display may help to locate fault.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM requires an accurate indication of fuel level for EVAP system diagnosis. Fuel level in fuel tank changes the rate of vacuum decay/change for EVAP system leak DTCs. Fuel level sensor changes resistance based on fuel level.

The IPC applies a voltage (about 12 volts) on signal circuit to sensor. IPC monitors changes in this voltage caused by changes in resistance of sensor to determine fuel level. When fuel tank is full, sensor signal voltage is high and vice-versa. This input is used to calculate fuel level in fuel tank.

DTC will set when PCM senses the fuel level signal voltage has not changed and vehicle has been operating for a specific amount of time.

Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle model.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor information is used by VCM to determine volume of fuel in fuel tank. Fuel level affects rate or change in air pressure in EVAP system.

Conditions for setting DTC

1. Fuel tank level slosh test is completed
2. Fuel tank main test is completed.
3. Fuel tank level data valid.
4. Fuel level signal has not changed for distance of 200 miles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, compare fuel level on scan tool and vehicle fuel gauge. If fuel levels are about the same, go to next step. If fuel level on scan tool and fuel gauge is not the same, go to step 4 .
3. DTC is intermittent. Check for additional DTCs set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel level sending unit harness connector at fuel tank. Turn ignition on, engine off. Using DVOM, check voltage between ground and fuel level signal circuit at harness connector. If voltage reading is about 5 volts, go to step 6 . If voltage reading is not about 5 volts, go to next step.
5. Repair open or short to ground in fuel level sender signal circuit. After repairs, go to step 9 .
6. Check fuel level sending unit for corrosion, faulty terminal connector, proper alignment to tank or for restricted/binding fuel level float. If problem is found, go to next step. If no problem is found, go to step 8 .
7. Repair as necessary. After repairs, go to step 9 .
8. Replace fuel level sending unit. After replacing sender, go to next step.
9. Using scan tool, record fuel level sensor voltage. Change fuel level in vehicle. If sensor voltage changes, go to next step. If sensor voltage does not change, repeat step 2 .
10. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for damaged harness or poor connection at VCM or fuel level sensor.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT MALFUNCTION (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor information is used by VCM to determine volume of fuel in fuel tank. Fuel level affects rate or change in air pressure in EVAP system.

Conditions for setting DTC

1. Fuel tank level slosh test is completed
2. Fuel tank main test is completed.
3. Fuel tank level data valid.
4. Fuel level signal has not changed for distance of 200 miles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, record fuel level sensor voltage. Change fuel level in fuel tank. Observe fuel level sensor voltage on scan tool. If fuel level sensor voltage changed on scan tool, go to next step. If fuel level sensor voltage did not change on scan tool, go to step 4 .
3. DTC is intermittent. Check if additional DTCs are set. diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Locate and disconnect fuel level sensor harness connector in fuel tank. Turn ignition on, engine off. Using DVOM connected to ground, probe fuel level sensor signal circuit. If voltage reading is about 5 volts, go to step 6 . If voltage reading is not about 5 volts, go to next step.
5. Repair open or short to ground in fuel level signal circuit. After repairs, go to step 9 .
6. Check fuel level sensor for corrosion and proper mating at connector. Check for proper alignment in fuel tank. Check for restricted/binding level float. If a problem is found, go to next step. If no problem is found, go to step 8 .
7. Repair as necessary. After repairs, go to step 9 .
8. Replace fuel level sender. After replacing sender, go to next step.
9. Using scan tool, record fuel level sensor voltage. Change fuel level in fuel tank. If fuel level sensor voltage changes, go to next step. If fuel level sensor voltage does not change, repeat step 2 .
10. Using scan tool, display CAPTURE and REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

Check for poor connection or damaged harness. Inspect VCM harness connectors for backed-out terminals, improper mating, broken locks or poor wire-to-terminal connections.

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. When fuel tank is full, sensor resistance is high. PCM monitors changes on signal circuit to determine fuel level. This information is sent to fuel gauge.

This diagnostic checks for stuck fuel level sensor signal. If PCM determines fuel level signal appears to be stuck based on lack of signal variation. DTC will set when more than 125 miles have been accumulated and fuel level does not decrease by at least 0.8 gallon (3 liters).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Disconnect fuel level sensor at fuel tank. Connect a fused jumper wire between chassis ground and fuel level sensor signal circuit at harness connector. Using scan tool, monitor fuel level sensor parameter. If scan tool reads zero volts, go to next step. If scan tool does not read zero volts, go to step 5 .
3. Connect a fused jumper wire between fuel level sensor connector signal and ground circuits at harness connector. Using scan tool monitor fuel level sensor. If scan tool reads zero volts, go to next step. If scan tool does not read zero volts, go to step 6 .
4. Remove fuel sender assembly. Check for loose or broken fuel tank baffle, stuck fuel level sensor or foreign material (ice) in fuel tank. Repair fuel tank as necessary. After repairs, go to step 10 . If fuel tank is okay, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor signal circuit for open or short to ground. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 8 .
6. Disconnect PCM harness connector. Check fuel level sensor signal and ground circuit for open. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 8 .
7. Replace fuel level sensor. After replacing sensor, go to step 10 .
8. Check for poor terminal connections at PCM. Repair terminals as necessary. After repairs, go to step 10 . If terminals are okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
10. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

With this DTC set, fuel gauge will display empty. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0461: FUEL LEVEL SENSOR CIRCUIT PERFORMANCE (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. When fuel tank is full, sensor resistance is high. PCM monitors changes on signal circuit to determine fuel level. This information is sent to fuel gauge.

Diagnostic checks for stuck fuel level sensor signal. If PCM determines fuel level signal appears to be stuck based on lack of signal variation, DTC P0461 sets.

DTC will set when the following conditions are present

1. Fuel level left fuel tank indicates does not decrease by at least 0.8 gallon (3 liters).
2. More than 150 miles have been accumulated.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Disconnect fuel level sensor connector at fuel tank. Using scan tool, read fuel level sensor voltage. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 5 .
3. Connect a fused jumper wire between fuel level sensor connector signal and ground circuits at harness connector. Using scan tool monitor fuel level sensor. If scan tool reads zero volts, go to next step. If scan tool does not read zero volts, go to step 6 .
4. Remove fuel level sensor (left tank). Check for loose or broken fuel tank baffle, stuck fuel level sensor or foreign material (ice) in fuel tank. Repair fuel tank as necessary. After repairs, go to step 10 . If fuel tank is okay, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor signal circuit for open or short to ground. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 8 .
6. Disconnect PCM harness connector. Check fuel level sensor signal and ground circuit for open. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 8 .
7. Replace fuel level sensor. After replacing sensor, go to step 10 .
8. Check terminal connections at PCM. Repair terminals as necessary. After repairs, go to step 10 . If terminals are okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
10. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0461. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 3 .
11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

With this DTC set, fuel gauge will display empty. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0462: FUEL LEVEL GAUGE CIRCUIT-LOW VOLTAGE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors resistance of fuel level sensor to calculate the amount of fuel in the tank and provides a voltage to the tank sender through a resistor network and a return to PCM ground. DTC P0462 will set if voltage remains less than 0.2 volt for longer than one second.

DTC will also set if monitored voltage in circuit is less than 0.2 volt for longer than one second when ignition voltage is greater than 9 volts.

PCM will command fuel gauge EMPTY and LOW FUEL light to turn on when DTC P0462 is set. DTC will clear (from active to history) if feedback if greater than 0.2 volt and ignition voltage is greater than 9 volts.

1. Install scan tool. Start engine. Using scan tool, monitor fuel sender voltage. If voltage reading is less than 0.2 volt, go to next step. If voltage reading is not less than 0.2 volt, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
2. Turn ignition off. Disconnect fuel gauge 3-pin connector. Turn ignition on, with engine off. Check if sender voltage is less than 0.2 volt. If voltage reading is less than 0.2 volt, go to next step. If voltage reading is not less than 0.2 volt, check circuit from fuel tank sender terminal "C" to 3-pin connector. Repair as necessary. If circuit is okay, replace tank sender.
3. Turn ignition off. Disconnect PCM harness connector J3. Turn ignition on, with engine off. If sender voltage is less than 0.2 volt, repair short in fuel tank sender terminal "C" circuit to 3-pin connector. If sender voltage is not less than 0.2 volt, replace PCM.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This supplemental data can be used to duplicate a problem. Check terminal connector tightness. A corroded or loose connection can cause DTC P0462 to set. Scan tool can be used to command fuel gauge and LOW FUEL light.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (2.2L "S" SERIES & 2.4L "N" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses fuel level input in order to calculate expected vapor pressure within the fuel system. Vapor pressure vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level to determine is fuel system is too high or too low to be able to accurately detect EVAP system faults.

DTC will set when fuel level sensor is less than 3.5 percent for greater than 25 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, check fuel level sensor value. If fuel level sensor value is greater than 3.5 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If fuel level sensor value is not greater than 3.5 percent, go to next step.
3. Disconnect fuel level sensor connector. If fuel level sensor value is now greater than 98 percent, go to step 5 . If fuel level sensor value is not greater than 98 percent, go to next step.
4. Check fuel level sensor signal circuit for short to ground. Repair as necessary. After repairs, go to step 7 . If circuit is okay, go to step 6 .
5. Replace fuel level sensor. After replacing sensor, go to step 7 .
6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
7. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, repeat step 2 .
8. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. If electrical interference is suspected, install additional ground wire from IPC to negative battery terminal.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (3.1L "W" BODY & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The PCM uses fuel level input in order to calculate expected vapor pressures within the fuel system. The vapor pressures will vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level information to determine if the fuel level is too high or too low to accurately detect an EVAP system malfunction.

Fuel level sensor value should be less than 3.5 percent for more than 25 seconds to set DTC.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than 3.5 percent, go to next step. If value is not greater than 3.5 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect fuel level sensor harness connector. Using scan tool, monitor fuel level sensor. If value is greater than 98 percent, go to step 5 . If value is not greater than 98 percent, go to next step.
4. Check fuel level sensor circuit for a short to ground. Repair as necessary. After repairs, go to step 7 . If circuit is okay, go to step 6 .
5. Replace fuel level sensor. After repairs, go to step 7 .
6. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
7. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
8. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM requires an accurate indication of fuel level for EVAP system diagnosis. Fuel level in fuel tank changes the rate of vacuum decay/change for EVAP system leak DTCs. Fuel level sensor changes resistance based on fuel level.

PCM applies about 5 volts on signal circuit to sensor. The PCM monitors changes in this voltage caused by changes in resistance of the sensor to determine fuel level. When fuel tank is full, sensor resistance is high and signal voltage is only pulled down a small amount through these sensor ground. When fuel tank is empty, sensor resistance is low and signal voltage is pulled down a greater amount.

PCM uses the input from the fuel level sensor to calculate the fuel level in the fuel tank. Fuel level data is used in EVAP system diagnostics. Fuel level data is also sent to the IPC via serial data. DTC will set when PCM detects a fuel level sensor signal below the normal operating range.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level display. If scan tool displays 1-100 percent, go to next step. If scan tool does not display 1-100 percent, go to step 4 .
3. Turn ignition off. Wait 15 seconds, then turn ignition on, with engine off. Using scan tool review and record FAILURE RECORDS conditions. Operate vehicle within these conditions. Using scan tool, monitor SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed in this ignition cycle, go to step 5 . If scan tool does not indicate that this DTC failed in this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. If fuel level parameter is stuck high, go to step 7 . If fuel level parameter is not stuck high, go to next step.
5. Ensure there is enough fuel in tank. Disconnect fuel level sensor harness connector. Observe fuel level sensor display on scan tool. If scan tool displays fuel level at greater than 100 percent, go to step 13 . If scan tool does not display fuel level at greater than 100 percent, go to next step.
6. Turn ignition off. Disconnect PCM harness connector. Check fuel level signal circuit for short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
7. Disconnect fuel level sensor harness connector. Using a DVOM, check voltage between ground and fuel level sensor signal circuit. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 11 .
8. Check voltage between fuel level sensor signal circuit and sensor ground circuit. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 12 .
9. Using a jumper wire, jumper signal circuit to ground circuit. If scan tool displays zero percent, go to next step. If scan tool does not display zero percent, go to step 15 .
10. Check for poor connections or terminal contact at fuel level sensor. Repair as necessary. After repairs, go to step 16 . If connections or terminal contacts are okay, go to next step.
11. Turn ignition off. Disconnect PCM harness connector. Check fuel level signal circuit for open or short to voltage. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
12. Turn ignition off. Disconnect PCM harness connector. Check continuity of sensor ground circuit from PCM to fuel level sensor harness connector. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
13. Replace fuel level sensor. After replacing sensor, go to step 16 .
14. Check for poor connections and terminals at PCM. Repair as necessary. After repairs, go to step 16 . If connections and terminals are okay, go to next step.
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, select DTC and CLEAR INFO function. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, repeat step 2 .
17. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle model.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (3.8L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. Fuel level sensor has a ground circuit and signal circuit. PCM applies about 5 volts to signal circuit. As fuel level changes, fuel level sensor changes resistance, in turn, causing a change in signal circuit voltage. PCM will monitor change in this voltage to determine fuel level.

When fuel tank is full, sensor resistance is high. With an empty fuel tank, sensor resistance will be low. By using these input signals, the PCM will determine the total amount of fuel remaining in fuel tank and sends this information to the fuel gauge.

This DTC will set when PCM senses a signal voltage less than normal operating range of sensor. For duplication of DTC, ignition must be on and fuel level sensor voltage must be less than 0.39 volt for at least 6 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than zero percent, go to next step. If value is not greater than zero percent, go to step 4 .
3. Turn ignition on, with engine off. Review FREEZE FRAME data for this DTC and note parameters. Clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0462 is set, go to next step. If DTC P0462 is not set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Disconnect fuel level sensor harness connector. Using scan tool, monitor fuel level sensor. If value is greater than zero percent, go to step 6 . If value is not greater than zero percent, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check fuel level sensor signal circuit for a short to ground. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 8 .
6. Check fuel sender pigtail circuits for short together or short to ground. Repair as necessary. After repairs, go to step 10 . If circuits are okay, go to next step.
7. Replace fuel level sensor. After repairs, go to step 10 .
8. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 10 . If connections are okay, go to next step.
9. Replace PCM. Program replacement PCM using required equipment. Perform CKP system variation learn procedure. After repairs, go to next step.
10. Using scan tool, clear DTCs. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

The fuel gauge will display EMPTY with this DTC set. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (3.8L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The PCM uses fuel level input in order to calculate expected vapor pressures within the fuel system. The vapor pressures will vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level information to determine if the fuel level is too high or too low to accurately detect an EVAP system malfunction.

Fuel level sensor value should be less than 3.5 percent for more than 25 seconds to set DTC.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than 3.5 percent, go to next step. If value is not greater than 3.5 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect fuel level sensor harness connector. Using scan tool, monitor fuel level sensor. If value is greater than 98 percent, go to step 5 . If value is not greater than 98 percent, go to next step.
4. Check fuel level sensor signal circuit for a short to ground. Repair as necessary. After repairs, go to step 7 . If circuit is okay, go to step 6 .
5. Replace fuel level sensor. After repairs, go to step 7 .
6. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
7. Using scan tool, clear DTCs. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
8. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM requires an accurate indication of fuel level for EVAP system diagnosis. Fuel level in fuel tank changes the rate of vacuum decay/change for EVAP system leak DTCs. Fuel level sensor changes resistance based on fuel level.

The IPC applies a voltage (about 12 volts) on signal circuit to sensor. IPC monitors changes in this voltage caused by changes in resistance of sensor to determine fuel level. When fuel tank is full, sensor signal voltage is high and vice-versa. This input is used to calculate fuel level in fuel tank.

DTC will set when PCM senses a signal voltage lower than normal operating range of sensor or fuel level sensor voltage drops to less than normal operating range for a specific length of time.

Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, see DIAGNOSTIC AIDS .

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle model.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor information is used by VCM to determine volume of fuel in fuel tank. Fuel level affects rate or change in air pressure in EVAP system.

Conditions required to set DTC are

1. Fuel tank level slosh test is completed
2. Fuel tank main level test is completed.
3. Fuel tank level data valid.
4. Fuel level signal less than 0.39 volt for a period greater than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, record fuel level sensor voltage. Change fuel level in fuel tank. If sensor voltage changed, go to next step. If sensor voltage did not change, go to step 4 .
3. DTC is intermittent. Check for additional DTCs set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel level sending unit harness connector at fuel tank. Turn ignition on, engine off. Using DVOM, check voltage between ground and fuel level signal circuit at harness connector. If voltage reading is about 5 volts, go to step 6 . If voltage reading is not about 5 volts, go to next step.
5. Repair open or short to ground in fuel level sender signal circuit. After repairs, go to step 9 .
6. Check fuel level sending unit for corrosion, faulty terminal connector, proper alignment to tank or for restricted/binding fuel level float. If problem is found, go to next step. If no problem is found, go to step 8 .
7. Repair as necessary. After repairs, go to step 9 .
8. Replace fuel level sending unit. After replacing sending unit, go to next step.
9. Using scan tool, record fuel level sensor voltage. Change fuel level in vehicle. If sensor voltage changes, go to next step. If sensor voltage does not change, repeat step 2 .
10. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for damaged harness or poor connection at VCM or fuel level sensor.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor information is used by VCM to determine volume of fuel in fuel tank. Fuel level affects rate or change in air pressure in EVAP system.

Conditions for setting DTC

1. Fuel tank level slosh test is completed
2. Fuel tank main test is completed.
3. Fuel tank level data valid.
4. Fuel level signal is less than 0.39 volt for greater than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe fuel level sensor voltage reading. If voltage reading is less than 0.39 volt, go to step 4 . If voltage reading is not less than 0.39 volt, go to next step.
3. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTICS AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel level sending unit harness connector at fuel tank. Turn ignition on, engine off. Using DVOM, check voltage between ground and fuel level signal circuit at harness connector. If voltage reading is about 5 volts, go to step 6 . If voltage reading is not about 5 volts, go to next step.
5. Check for short to ground in fuel level signal circuit. If circuit is shorted, go to step 7 . If circuit is okay, go to step 9 .
6. Check fuel level sending unit for corrosion, faulty terminal connector, proper alignment to tank or for restricted/binding fuel level float. If problem is found, go to next step. If no problem is found, go to step 8 .
7. Repair as necessary. After repairs, go to step 10 .
8. Replace fuel level sending unit. After replacing sender, go to step 10 .
9. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
10. Using scan tool, select DTC and CLEAR INFO function. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, repeat step 2 .
11. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for damaged harness or poor connection at VCM or fuel level sensor.

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. When fuel tank is full, sensor resistance is high. PCM monitors changes on signal circuit to determine fuel level. This information is sent to fuel gauge.

DTC will set when PCM senses fuel level signal voltage less than 0.39 volt for 2 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor voltage. If voltage reading is less than 0.39 volt, go to step 4 . If voltage reading is not less than 0.39 volt, go to next step.
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter this DTC. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel level sensor connector. Turn ignition on. Using scan tool, monitor fuel level sensor voltage. If voltage reading is less than 0.39 volt, go to step 5 . If voltage reading is not less than 0.39 volt, go to step 7 .
5. Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor signal circuit for short to ground. If circuit is grounded, go to next step. If circuit is okay, go to step 8 .
6. Repair grounded circuit between PCM connector and fuel level sensor. After repairs, go to step 9 .
7. Replace fuel level sensor. After replacing sensor, go to step 9 .
8. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

With this DTC set, fuel gauge will display empty. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0462: FUEL LEVEL SENSOR CIRCUIT-LOW VOLTAGE (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. When fuel tank is full, sensor resistance is high. PCM monitors changes on signal circuit to determine fuel level. This information is sent to fuel gauge.

If PCM senses fuel level signal voltage lower than 0.39 volt, DTC P0462 sets.

DTC will set when the following conditions are present

1. Fuel level sensor voltage is less than 0.39 volt.
2. Conditions present for 6 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P1639. If DTC P1639 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
3. Using scan tool, read fuel level sensor voltage. If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step 5 .
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0462. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect fuel level sensor at body pass-through connector. Using scan tool, read fuel level sensor voltage. If voltage is about 5 volts, go to step 7 . If voltage reading is not as specified, go to next step.
6. Turn ignition off. Disconnect PCM harness connector C2. Check fuel level sensor signal circuit for short to ground. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to step 9 .
7. Lower fuel tank. Check for damaged fuel level sensor harness. Repair as necessary. After repairs, go to step 11 . If harness is okay, go to next step.
8. Replace fuel level sensor. After repairs, go to step 11 .
9. Check terminal tension at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If terminal tension is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
11. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0462. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

With this DTC set, fuel gauge will display empty. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0463: FUEL LEVEL GAUGE CIRCUIT-HIGH VOLTAGE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors resistance of fuel level sensor to calculate the amount of fuel in the tank and provides a voltage to the tank sender through a resistor network and a return to PCM ground. DTC P0462 will set if voltage remains greater than 4.86 volts for longer than one second.

DTC will also set if the monitored voltage in the circuit is greater than 4.86 volts for longer than one second when ignition voltage is greater than 9 volts.

PCM will command fuel gauge to EMPTY and LOW FUEL light to turn on when DTC P0462 is set. DTC will clear (from active to history) if feedback if less than 4.86 volts and ignition voltage is greater than 13 volts.

1. Install scan tool. Start engine. Using scan tool, monitor fuel sender voltage. If voltage reading is greater than 4.9 volts, go to next step. If voltage reading is not greater than 4.9 volts, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
2. Using a 5-amp fused jumper wire connected to ground, backprobe 3-pin connector terminal to tank sender terminal "C". Check scan tool reading. If fuel sender voltage reading is greater than 4.9 volts, go to next step. If fuel tank sender voltage is not greater than 4.9 volts, go to step 4 .
3. If fuse on jumper wire blew, repair short to voltage in circuit. If fuse did not blow, check for open in circuit, terminal tightness or faulty PCM.
4. Using a 5-amp fused jumper wire connected to ground, backprobe 3-pin connector terminal to tank sender terminal "B". Check scan tool reading. If fuel sender voltage is greater than 4.9 volts, check for open circuit between 3-pin connector and tank sender unit, terminal tightness or faulty sender unit. If fuel sender voltage is not greater than 4.9 volts, check for open circuit between 3-pin connector and PCM, terminal tightness or faulty PCM.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This supplemental data can be used to duplicate a problem. Scan tool can be used to command fuel gauge and LOW FUEL light.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (2.2L "S" SERIES & 2.4L "N" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses fuel level input in order to calculate expected vapor pressure within the fuel system. Vapor pressure vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level to determine is fuel system is too high or too low to be able to accurately detect EVAP system faults.

DTC will set when fuel level sensor is greater than 98 percent for greater than 25 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, engine off. Using scan tool, check fuel level sensor value. If fuel level sensor value is greater than 98 percent, go to next step. If fuel level sensor value is not greater than 98 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect fuel level sensor connector. If fuel level sensor value is now less than 3.5 percent, go to step 5 . If fuel level sensor value is not less than 3.5 percent, go to next step.
4. Jumper fuel level sensor signal circuit at sensor connector to chassis ground. If fuel level sensor value is now greater than 3.5 percent, go to next step. If sensor value is not greater than 3.5 percent, go to step 6 .
5. Check for poor connections at fuel level sensor. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to step 9 .
6. Check for open in fuel level sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to step 8 .
7. Check for open in fuel level sensor signal circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for poor sensor ground or signal circuit connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If circuit and connections are okay, go to step 10 .
9. Replace fuel level sensor. After replacing sensor, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, repeat step 2 .
12. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. If electrical interference is suspected, install additional ground wire from IPC to negative battery terminal.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (3.1L "W" BODY & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The PCM uses fuel level input in order to calculate expected vapor pressures within the fuel system. The vapor pressures will vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level information to determine if the fuel level is too high or too low to accurately detect an EVAP system malfunction.

Fuel level sensor value should be greater than 98 percent for more than 25 seconds to set DTC.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than 98 percent, go to next step. If value is not greater than 98 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect fuel level sensor harness connector. Using a fused jumper wire, jumper fuel level sensor signal and ground circuits together at harness connector. Using scan tool, monitor fuel level sensor. If value is less than 3.5 percent, go to step 5 . If value is not less than 3.5 percent, go to next step.
4. Using a fused jumper wire, jumper fuel level sensor signal circuit at harness connector to ground. Using scan tool, monitor fuel level sensor. If value is less than 3.5 percent, go to step 6 . If value is not less than 3.5 percent, go to step 7 .
5. Check for faulty connections at fuel level sensor. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to step 9 .
6. Check for open in fuel level sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to step 8 .
7. Check for open in fuel level sensor signal circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to step 10 .
9. Replace fuel level sensor. After repairs, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
11. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting the DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
12. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM requires an accurate indication of fuel level for EVAP system diagnosis. Fuel level in fuel tank changes the rate of vacuum decay/change for EVAP system leak DTCs. Fuel level sensor changes resistance based on fuel level.

PCM applies about 5 volts on signal circuit to sensor. The PCM monitors changes in this voltage caused by changes in resistance of the sensor to determine fuel level. When fuel tank is full, sensor resistance is high and signal voltage is only pulled down a small amount through these sensor ground. When fuel tank is empty, sensor resistance is low and signal voltage is pulled down a greater amount.

PCM uses the input from the fuel level sensor to calculate the fuel level in the fuel tank. Fuel level data is used in EVAP system diagnostics. Fuel level data is also sent to the IPC via serial data. DTC will set when PCM detects a fuel level sensor signal greater than the normal operating range.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level display. If scan tool displays 1-100 percent, go to next step. If scan tool does not display 1-100 percent, go to step 4 .
3. Turn ignition off. Wait 15 seconds, then turn ignition on, with engine off. Using scan tool review and record FAILURE RECORDS conditions. Operate vehicle within these conditions. Using scan tool, monitor SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed in this ignition cycle, go to step 5 . If scan tool does not indicate that this DTC failed in this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. If fuel level parameter is stuck high, go to step 7 . If fuel level parameter is not stuck high, go to next step.
5. Ensure there is enough fuel in tank. Disconnect fuel level sensor harness connector. Observe fuel level sensor display on scan tool. If scan tool displays fuel level at greater than 100 percent, go to step 13 . If scan tool does not display fuel level at greater than 100 percent, go to next step.
6. Turn ignition off. Disconnect PCM harness connector. Check fuel level signal circuit for short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
7. Disconnect fuel level sensor harness connector. Using a DVOM, check voltage between ground and fuel level sensor signal circuit. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 11 .
8. Check voltage between fuel level sensor signal circuit and sensor ground circuit. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 12 .
9. Using a jumper wire, jumper signal circuit to ground circuit. If scan tool displays zero percent, go to next step. If scan tool does not display zero percent, go to step 15 .
10. Check for poor connections or terminal contact at fuel level sensor. Repair as necessary. After repairs, go to step 16 . If connections or terminal contacts are okay, go to next step.
11. Turn ignition off. Disconnect PCM harness connector. Check fuel level signal circuit for open or short to voltage. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
12. Turn ignition off. Disconnect PCM harness connector. Check continuity of sensor ground circuit from PCM to fuel level sensor harness connector. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
13. Replace fuel level sensor. After replacing sensor, go to step 16 .
14. Check for poor connections and terminals at PCM. Repair as necessary. After repairs, go to step 16 . If connections and terminals are okay, go to next step.
15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
16. Using scan tool, select DTC and CLEAR INFO function. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, repeat step 2 .
17. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle model.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (3.8L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. Fuel level sensor has a ground circuit and signal circuit. PCM applies about 5 volts to signal circuit. As fuel level changes, fuel level sensor changes resistance, in turn, causing a change in signal circuit voltage. PCM will monitor change in this voltage to determine fuel level.

When fuel tank is full, sensor resistance is high. With an empty fuel tank, sensor resistance will be low. By using these input signals, the PCM will determine the total amount of fuel remaining in fuel tank and sends this information to the fuel gauge.

This DTC will set when PCM senses a signal voltage greater than normal operating range of sensor. For duplication of DTC, ignition must be on and fuel level sensor voltage must be greater than 2.9 volts for at least 6 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than 100 percent, go to step 4 . If value is not greater than 100 percent, go to next step.
3. Turn ignition on, with engine off. Review FREEZE FRAME data for this DTC and note parameters. Clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0463 is set, go to next step. If DTC P0463 is not set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Disconnect fuel level sensor harness connector. Measure voltage between ground and fuel level sensor circuit at harness connector. If voltage is less than 5.5 volts, go to next step. If voltage is not less than 5.5 volts, go to step 7 .
5. Using a fused jumper wire, jumper fuel level sensor signal and ground circuit terminals together at fuel level sensor harness connector. Using scan tool, monitor fuel level sensor. If value is less than 100 percent, go to step 11 . If value is not less than 100 percent, go to next step.
6. Using a fused jumper wire, jumper fuel level sensor signal circuit to ground. Using scan tool, monitor fuel level sensor. If value is less than 100 percent, go to step 10 . If value is not less than 100 percent, go to step 8 .
7. Disconnect PCM harness connectors. Check fuel level sensor signal circuit for a short to voltage. If circuit is shorted, go to step 9 . If circuit is okay, go to step 14 .
8. Turn ignition off. Disconnect PCM harness connectors. Check for open in fuel level sensor signal circuit. If circuit is open, go to next step. If circuit is okay, go to step 13 .
9. Repair fuel level sensor signal circuit. After repairs, go to step 15 .
10. Turn ignition off. Disconnect PCM harness connectors. Check for open in fuel level sensor ground circuit. If circuit is open, go to step 12 . If circuit is okay, go to step 13 .
11. Replace fuel level sensor. After repairs, go to step 15 .
12. Repair fuel level sensor ground circuit. After repairs, go to step 15 .
13. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
14. Replace PCM. Program replacement PCM using required equipment. Perform CKP system variation learn procedure. After repairs, go to next step.
15. Using scan tool, clear DTCs. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
16. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

The fuel gauge will display EMPTY with this DTC set. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (3.8L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The PCM uses fuel level input in order to calculate expected vapor pressures within the fuel system. The vapor pressures will vary as fuel level changes. Vapor pressure is critical in determining if EVAP system is operating properly. PCM also uses fuel level information to determine if the fuel level is too high or too low to accurately detect an EVAP system malfunction.

Fuel level sensor value should be greater than 98 percent for more than 25 seconds to set DTC.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor. If value is greater than 98 percent, go to next step. If value is not greater than 98 percent, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Disconnect fuel level sensor harness connector. Using a fused jumper wire, jumper fuel level sensor signal and ground circuit terminals together at harness connector. Using scan tool, monitor fuel level sensor. If value is less than 3.5 percent, go to step 5 . If value is not less than 3.5 percent, go to next step.
4. Using a fused jumper wire, jumper fuel level sensor signal circuit to ground. Using scan tool, monitor fuel level sensor. If value is less than 3.5 percent, go to step 6 . If value is not less than 3.5 percent, go to step 7 .
5. Check for faulty connections at fuel level sensor. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to step 9 .
6. Check for open in fuel level sensor ground circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to step 8 .
7. Check for open in fuel level sensor signal circuit. Repair as necessary. After repairs, go to step 11 . If circuit is okay, go to next step.
8. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 11 . If connections are okay, g to step 10 .
9. Replace fuel level sensor. After repairs, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
11. Using scan tool, clear DTCs. Warm engine to normal operating temperature. Select DTC and SPECIFIC DTC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this diagnostic ran and passed, go to next step. If scan tool does not indicate that this diagnostic ran and passed, go to step 2 .
12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM requires an accurate indication of fuel level for EVAP system diagnosis. Fuel level in fuel tank changes the rate of vacuum decay/change for EVAP system leak DTCs. Fuel level sensor changes resistance based on fuel level.

The IPC applies a voltage (about 12 volts) on signal circuit to sensor. IPC monitors changes in this voltage caused by changes in resistance of sensor to determine fuel level. When fuel tank is full, sensor signal voltage is high and vice-versa. This input is used to calculate fuel level in fuel tank.

DTC will set when PCM senses the fuel level signal voltage is higher than normal operating range of sensor or fuel level sensor voltage goes above normal operating range for a specific amount of time.

Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, see DIAGNOSTIC AIDS .

Always diagnose fuel level sensor before any other EVAP system components or DTCs. Do not use fuel gauge as an indication of a shorted or open circuit as IPC may always default to EMPTY or FULL depending on vehicle model.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor is an important input to VCM for enhanced evaporative system diagnostic. Fuel level is necessary for VCM to know volume of fuel in fuel tank. Fuel level affects rate of change in air pressure in EVAP system. Several enhanced evaporative system diagnostic sub-tests are dependent upon correct fuel level information. Diagnostic will not run when tank is greater than 85 percent or less than 15 percent full. Sensor signal will disable misfire when fuel levels are less than 15 percent.

Conditions for setting DTC

1. Fuel tank level slosh test is completed.
2. Fuel tank level main test is completed.
3. Fuel tank level data valid.
4. Fuel level signal voltage is greater than 2.9 volts for a period longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe fuel level sensor voltage. If voltage reading is greater than 2.9 volts, go to step 4 . If voltage reading is not greater than 2.9 volts, go to next step.
3. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTC. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel level sensor connector at fuel tank. Turn ignition on, engine off. Check voltage between ground and fuel level signal circuit at harness connector. If voltage reading is about 5 volts, go to step 6 . If voltage reading is not about 5 volts, go to next step.
5. Check for open in fuel level sender signal circuit. If circuit is open, go to step 10 . If circuit is okay, go to step 8 .
6. Using test light connected to battery voltage, probe fuel level sender ground circuit. If test light illuminates, go to step 10 . If test light does not illuminate, go to step 7 .
7. Check for short to voltage in fuel level sender signal circuit. If circuit is shorted, go to step 10 . If circuit is okay, go to step 12 .
8. Check for open in fuel level sender ground circuit. If circuit is shorted, go to step 10 . If circuit is okay, go to step 12 .
9. Repair harness connector at fuel level sender for corrosion or improper mating. If problem is found, go to next step. If connection is okay, go to step 11 .
10. Repair circuit as necessary. After repairs, go to step 13 .
11. Replace fuel level sender. After replacing fuel level sender, go to step 13 .
12. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0462. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for damaged harness or poor connection at VCM or fuel level sensor.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor is an important input to VCM for enhanced evaporative system diagnostic. Fuel level is necessary for VCM to know volume of fuel in fuel tank. Fuel level affects rate of change in air pressure in EVAP system. Several enhanced evaporative system diagnostic sub-tests are dependent upon correct fuel level information. Diagnostic will not run when tank is greater than 85 percent or less than 15 percent full. Sensor signal will disable misfire when fuel levels are less than 15 percent.

Conditions for setting DTC

1. Fuel tank level slosh test is completed.
2. Fuel tank level main test is completed.
3. Fuel tank level data valid.
4. Fuel level signal voltage is greater than 2.9 volts for a period longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, observe fuel level sensor voltage reading. If voltage reading is greater than 2.9 volts, go to step 4 . If voltage reading is not greater than 2.9 volts, go to next step.
3. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. Turn ignition off. Disconnect fuel tank level sensor connector at fuel tank. Using DVOM connected to ground, probe fuel level sensor signal circuit. If voltage reading is about 5 volts, go to step 6 . If fuel voltage is not about 5 volts, go to next step.
5. Check for open in fuel level sensor input circuit. If a problem is found, go to step 10 . If no problem is found, go to next step.
6. Using test light connected to battery voltage, probe fuel level ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
7. Check for short to voltage in fuel level signal circuit. If circuit is shorted, go to step 10 . If circuit is okay, go to step 12 .
8. Check for open in fuel level ground circuit. If circuit is open, go to step 10 . If circuit is okay, go to step 12 .
9. Check connector at fuel level sensor for corrosion or improper mating. If problem is found, go to next step. If connector is okay, go to step 11 .
10. Repair circuit as necessary. After repairs, go to step 13 .
11. Replace fuel level sender. After replacing fuel level sender, go to step 13 .
12. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool indicates that this DTC RAN AND PASSED, go to next step. If scan tool does not indicate that this DTC RAN AND PASSED, repeat step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection. If electrical interference is suspected, install additional ground wire from IPC to negative battery terminal.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. PCM applies about 5 volts on the signal circuit to the sensor. PCM monitors changes in this voltage caused by changes in resistance of the sensor to determine fuel level. When fuel tank is full, sensor resistance is high, and PCM signal voltage is only pulled down a small amount through sensor ground. When fuel tank is empty, sensor resistance is low, and signal voltage is pulled down a greater amount. This causes the PCM to sense a low signal voltage (fuel tank empty).

PCM uses inputs from the fuel level sensor in order to calculate the total fuel remaining in fuel tank. PCM uses fuel level information for the EVAP and misfire diagnostics. DTC will set when the PCM senses a signal voltage higher than the normal operating range of the sensor. DTC will also set when fuel level sensor voltage is greater than 2.9 volts for 2 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Warm engine to normal operating temperature. Using scan tool, check if DTC P1635 and P1639 is present. If DTCs are set, diagnose affected DTCs first. If DTC P1635 and P1639 are not set, go to next step.
3. Turn ignition on, with engine off. Using scan tool, observe fuel level sensor voltage. If voltage reading is greater than 2.9 volts, go to step 5 . If voltage reading is not greater than 2.9 volts, go to next step.
4. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data for this DTC and observe parameters. Turn ignition off for 15 seconds, then start engine. Operate vehicle within conditions for setting this DTC and as close as the conditions recorded in FREEZE FRAME and/or FAILURE RECORD as possible. Select DTC and SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this diagnostic failed this ignition cycle, go to next step. If scan tool does not indicate that this diagnostic failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Turn ignition off. Disconnect fuel level sender connector at fuel tank. Using a jumper wire, jumper fuel level sensor harness connector terminals. Turn ignition on, engine off. Using scan tool, monitor fuel level sensor voltage. If fuel sensor voltage is less than 2.9 volts, go to step 8 . If voltage reading is not less than 2.9 volts, go to next step.
6. Connect jumper between a good ground and fuel level sensor signal circuit. Using scan tool, monitor fuel level sensor voltage. If fuel level sensor voltage is less than 2.9 volts, go to step 9 . If fuel level sensor voltage is not less than 2.9 volts, go to next step.
7. Turn ignition off. Disconnect PCM harness connector C2. Check for open in fuel level sensor signal circuit from PCM harness connector. If circuit is open, go to step 12 . If circuit is not open, go to step 15 .
8. Turn ignition off. Remove jumper wire from fuel level sensor harness connector. Disconnect PCM harness connector. Check resistance from fuel level sensor signal circuit at PCM harness connector to all other circuit at PCM harness connectors. If resistance is 0-2 ohms, go to step 14 . If resistance is not 0-2 ohms, go to step 10 .
9. Turn ignition off. Disconnect PCM harness connector C1. Check for open in fuel level sensor ground circuit. If circuit is open, go to step 13 . If circuit is not open, go to step 15 .
10. Check for poor connection at fuel level sensor harness connector. Repair as necessary. After repairs, go to step 17 . If connection is okay, go to next step.
11. Replace fuel level sensor. After replacing fuel level sensor, go to step 17 .
12. Repair open in fuel level sensor signal circuit. After repairs, go to step 17 .
13. Repair open in fuel level sensor ground signal. After repairs, go to step 17 .
14. Repair short to voltage in fuel level sensor signal circuit. After repairs, go to step 17 .
15. Check for poor connections at PCM harness connector. Repair as necessary. After repairs, go to step 17 . If connections are okay, go to next step.
16. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
17. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2 .
18. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for damaged harness or poor connection at VCM or fuel level sensor.

DTC P0463: FUEL LEVEL SENSOR CIRCUIT-HIGH VOLTAGE (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Fuel level sensor changes resistance based on fuel level. When fuel tank is full, sensor resistance is high. PCM monitors changes on signal circuit to determine fuel level. This information is sent to fuel gauge.

If PCM senses fuel level signal voltage greater than 2.9 volts, DTC P0463 sets. For duplication of DTC, ensure fuel level sensor voltage is greater than 2.9 volts.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P1639. If DTC P1639 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
3. Using scan tool, read fuel level sensor voltage. If voltage reading is greater than 2.9 volts, go to step 5 . If voltage reading is not as specified, go to next step.
4. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter DTC P0463. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect fuel level sensor connector. Connect a fused jumper wire between fuel level sensor connector signal and ground circuits. If voltage reading is greater than 2.9 volts, go to step 10 . If voltage reading is not as specified, go to next step.
6. Connect jumper wire between ground and fuel level sensor connector signal circuit. If voltage reading is greater than 2.9 volts, go to step 9 . If voltage reading is not as specified, go to next step.
7. Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor signal circuit for open. If circuit is open, go to next step. If circuit is okay, go to step 12 .
8. Repair fuel level sensor signal circuit as necessary. After repairs, go to step 13 .
9. Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor ground circuit for open. If circuit is open, go to step 11 . If circuit is okay, go to step 12 .
10. Replace fuel level sensor. After replacing sensor, go to step 13 .
11. Repair fuel level sensor ground circuit as necessary. After repairs, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0463. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

With this DTC set, fuel gauge will display empty. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN CIRCUIT (2.2L "J" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The cooling fan is controlled by PCM through the cooling fan relay based on inputs from ECT sensor, IAT sensor, A/C selector switch, A/C refrigerant pressure switch and vehicle speed sensor. PCM controls cooling fan by grounding cooling fan control circuit which turns on cooling fan relay.

The fan relay will be commanded on when ECT reaches 223°F (106°C) or greater, A/C is requested or vehicle speed is less than 38 MPH. Cooling fan relay will also be commanded on regardless of vehicle speed when a DTC is set requesting cooling fan to be on, ECT is 304°F (151°C) or greater, or A/C refrigerant pressure is high. Cooling fan may also be commanded on when engine is not running, on certain conditions.

For duplication of DTC, ensure battery voltage greater than 9.5 volts, and cooling fan fault line detects a malfunction for 6 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Check cooling system. Ensure coolant level and belt tension are correct. Adjust/repair as necessary. After repairs, go to step 24 . If no adjustment or repairs were required, go to next step.
3. Turn ignition on, with engine off. Using scan tool, check if cooling fan is operating with ECT at less than 209°F (98°C). If cooling fan is off, go to next step. If cooling fan is on, go to step 5 .
4. Command cooling fan relay on. If cooling fan operates, go to step 24 . If cooling fan does not operate, go to step 6 .
5. Turn ignition off. Disconnect PCM harness connector. If cooling fan turns off, go to step 23 . If cooling fan does not turn off, go to step 7 .
6. Disconnect cooling fan relay harness connector. Using a test light connected to ground, probe battery feed circuits in relay harness connector. If test light illuminates on both terminals, go to step 8 . If test light does not illuminate on both terminals, go to step 9 .
7. Disconnect cooling fan relay harness connector. With test light connected to ground, probe battery feed circuit in relay harness connector. If test light illuminates, go to step 10 . If test light does not illuminate, go to step 11 .
8. Connect a jumper wire between cooling fan relay battery feed and cooling fan battery feed circuit. If cooling fan operates, go to step 12 . If cooling fan does not operate, go to step 13 .
9. Repair open in battery feed circuit. After repairs, go to step 24 .
10. Repair short to voltage in cooling fan battery feed circuit. After repairs, go to step 24 .
11. Connect test light battery voltage and probe cooling fan control circuit. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 22 .
12. Connect test light to battery voltage and probe cooling fan control circuit. Using scan tool, command cooling fan on. If test light illuminates, go to step 15 . If test light does not illuminate, go to step 16 .
13. With jumper wire still connected, disconnect cooling fan harness connector. Using test light connected to ground, probe cooling fan battery feed circuit. If test light illuminates, go to step 17 . If test light does not illuminate, go to step 18 .
14. Repair short to ground in cooling fan control circuit. After repairs, go to step 24 .
15. Check terminals to cooling fan relay. Repair as necessary. After repairs, go to step 24 . If terminals are okay, go to step 22 .
16. Check cooling fan control circuit for open or poor connection. Repair as necessary. After repairs, go to step 24 . If circuit or connection is okay, go to step 23 .
17. Connect test light to battery voltage and probe cooling fan ground circuit. If test light illuminates, go to step 19 . If test light does not illuminate, go to step 20 .
18. Repair open or poor connection in cooling fan ignition feed circuit. After repairs, go to step 24 .
19. Check for poor connections at cooling fan harness connector. Repair as necessary. After repairs, go to step 24 . If connections are okay, go to step 21 .
20. Repair open or poor connection in cooling fan ground circuit. After repairs, go to step 24 .
21. Replace cooling fan motor. After replacing cooling fan motor, go to step 24 .
22. Replace cooling fan relay. After replacing relay, go to step 24 .
23. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
24. Turn ignition on, with engine off. Command cooling fan on. If cooling fan operates, go to next step. If cooling fan does not operate, repeat step 2 .
25. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
26. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If complaint is an overheating problem, determine if complaint is due to an actual boil-over, temperature light, or if temperature gauge indicated overheating.

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The cooling fan is controlled by the Body Function Controller (BFC). BFC sends a Class II message to PCM in order to enable the fans based on various inputs. Ignition voltage travels to all 3 cooling fan relays. PCM provides ground path to relays. When PCM detects that certain DTCs are set, PCM will enable cooling fans.

DTC will set when PCM detects that commanded state of driver and actual state of control circuit do not match.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay on and off. If cooling fan relay No. 1 turns on and off, go to next step. If cooling fan relay No. 1 does not turn on and off, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using DVOM in 10-amp scale, check current from cooling fan relay No. 1 control circuit in PCM connector to ground for 2 minutes. If current draw is less than 0.75 amp, but not zero, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is not less than 0.75 amp, go to next step.
4. Turn ignition off. Disconnect cooling fan relay No. 1. Check resistance between ground and fan relay No. 1 control circuit at PCM harness connector. If resistance is infinite, go to step 12 . If resistance is not infinite, go to step 10 .
5. Turn ignition off. Disconnect cooling fan relay No. 1. Connect test light between relay No. 1 control terminal and battery feed terminal in relay harness connector. Turn ignition on. Using scan tool, command relay No. 1 on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off, go to next step.
6. Connect test light between ground and relay No. 1 battery feed circuit in harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
7. Turn ignition off. Reconnect cooling fan relay No. 1 relay. Disconnect PCM harness connector. Turn ignition on. Using a fused jumper wire, connect jumper between ground and cooling fan relay No. 1 control circuit at PCM connector. If relay operates, go to step 9 . If relay does not operate, go to step 10 .
8. Check connections at cooling fan control relay No. 1. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 12 .
9. Check connections at PCM. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 13 .
10. Repair relay No. 1 control circuit. After repairs, go to step 14 .
11. Repair relay No. 1 battery feed circuit. After repairs, go to step 14 .
12. Replace cooling fan relay No. 1. After replacing relay, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (3.1L "W" BODY & 3.4L "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay No. 1 on and off. If relay turns on and off, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If relay does not turn on and off, go to next step.
3. Turn ignition off. Remove relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay coil battery feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between relay coil battery feed circuit and relay control circuit. Using scan tool, command relay on and off. If test light turns on and off, go to step 8 . If test light does not turn on and off, go to next step.
5. If test light remains illuminated for each command, go to step 7 . If test light does not remain illuminated for each command, go to next step.
6. Check relay control circuit for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay coil battery feed circuit. After repairs, go to step 13 .
11. Replace relay. After repairs, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0480. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Ignition voltage is supplied directly to Fan Control (FC) relay No. 1. PCM controls relay by grounding the control circuit through an internal solid state device called the driver. The driver supplies the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When PCM is commanding a component on, the control circuit should be low (near zero volts). When PCM is commanding a component off, the control circuit should be high (near battery voltage).

If the fault detection circuit senses a voltage other than what is expected, this DTC will set. This DTC will also set when there is a short to ground, open in circuit, or short to battery voltage is detected on control circuit and when condition is present for at least 30 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay on and off. If cooling fan relay No. 1 turns on and off, go to next step. If cooling fan relay No. 1 does not turn on and off, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using DVOM in 10-amp scale, check current from cooling fan relay No. 1 control circuit in PCM connector to ground for 2 minutes. If current draw is 0.10-0.75 amp, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is 0.10-0.75 amp, go to next step.
4. Turn ignition off. Disconnect cooling fan relay. Check resistance between ground and fan relay control circuit at PCM harness connector. If resistance is infinite, go to step 11 . If resistance is not infinite, go to step 9 .
5. Turn ignition off. Disconnect cooling fan relay. Connect test light between relay control terminal and battery feed terminal in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off, go to next step.
6. Connect test light between ground and relay battery feed circuit in harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
7. Turn ignition off. Reconnect cooling fan relay. Disconnect PCM harness connector. Turn ignition on. Using a fused jumper wire, connect jumper between ground and cooling fan relay control circuit at PCM connector. If relay operates, go to step 12 . If relay does not operate, go to step 9 .
8. Check connections at cooling fan control relay. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 11 .
9. Repair relay control circuit. After repairs, go to step 14 .
10. Repair ignition feed circuit to relay. After repairs, go to step 14 .
11. Replace cooling fan relay. After replacing relay, go to step 14 .
12. Check for poor terminal connection at PCM harness connector. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (3.8L "C", "F" & "G" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay No. 1 on and off. If relay turns on and off, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If relay does not turn on and off, go to next step.
3. Turn ignition off. Remove relay. Turn ignition on, with engine off. Using a test light connected to ground, probe relay coil battery feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
4. Connect test light between relay coil battery feed circuit and relay control circuit. Using scan tool, command relay on and off. If test light turns on and off, go to step 8 . If test light does not turn on and off, go to next step.
5. If test light remains illuminated for each command, go to step 7 . If test light does not remain illuminated for each command, go to next step.
6. Check relay control circuit for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
7. Check relay control circuit for short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair relay coil battery feed circuit. After repairs, go to step 13 .
11. Replace relay. After repairs, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0480. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (3.8L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, capture FAILURE RECORDS data. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Measure voltage between ground and low speed fans relay driver circuit at PCM harness connector. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 6 .
3. Using DVOM set on 10-amp scale, measure current between ground and low speed fans relay driver circuit at PCM harness connector. If current remains 0.1-1.5 amps, go to step 11 . If current does not remain 0.1-1.5 amps, go to next step.
4. Disconnect relay. Measure voltage between ground and low speed fans relay driver circuit at PCM harness connector. If voltage is zero volts, go to step 14 . If voltage is not zero volts, go to next step.
5. Repair short to voltage in low speed fans relay driver circuit. After repairs, go to step 16 .
6. Check fuse supplying power to relay. If fuse is open, go to next step. If fuse is okay, go to step 8 .
7. Repair short to ground in battery feed circuit to relay. After repairs, go to step 16 .
8. Remove relay. Turn ignition on. Measure voltage between ground and ignition feed circuit for relay. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 13 .
9. Check low speed fans relay driver circuit for an open or short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to next step.
10. Check low speed fans relay control circuit and ignition feed circuit for faulty connections at relay and PCM. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 14 .
11. Turn ignition off. Reconnect PCM harness connectors. Disconnect relay. Turn ignition on. Connect a test light between low speed fans control circuit and ignition feed circuit at relay harness connector. Using scan tool, command relay on and off. If test light turns on and off, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If test light does not turn on and off, go to next step.
12. Check low speed fans control circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 16 . If connections are okay, go to step 15 .
13. Repair open in battery feed circuit to relay. After repairs, go to step 16 .
14. Replace relay. After repairs, go to step 16 .
15. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
16. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0480. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0480: COOLING FAN RELAY NO. 1 CONTROL CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Ignition voltage is supplied directly to cooling fan relay coil. PCM controls relay by grounding control circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when the following conditions are present

1. Engine speed greater than 600 RPM.
2. Ignition voltage between 6-16 volts.
3. PCM detects commanded state of driver and actual state do not match.
4. Conditions met for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay No. 1 on and off. If relay turns on and off as commanded, go to next step. If relay does not turn on or off when commanded, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a DVOM set to 10-amp scale, check current from relay control circuit in PCM harness connector to ground for 2 minutes. If current draw is less than 0.75 amp (but not zero), see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is not as specified, go to next step.
4. Turn ignition off. Disconnect cooling fan relay No. 1. Check resistance from relay control circuit in PCM harness connector to ground. If resistance is infinite, go to step 12 . If resistance is not infinite, go to step 10 .
5. Turn ignition off. Disconnect cooling fan relay No. 1. Connect test light between relay coil terminals in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to next step.
6. Connect test light to ground and probe ignition feed circuit in cooling fan relay No. 1 harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
7. Turn ignition off. Reconnect cooling fan relay No. 1. Disconnect PCM harness connector containing relay control circuit. Turn ignition on. Connect a fused jumper wire between ground and PCM connector (harness side) relay control circuit. If relay operates, go to step 9 . If relay does not operate, go to step 10 .
8. Check connections at cooling fan relay No. 1. Repair as necessary. After repairs, go to step 14 . If relay connection is okay, go to step 12 .
9. Check connections at PCM. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 13 .
10. Repair faulty cooling fan relay No. 1 control circuit. After repairs, go to step 14 .
11. Repair faulty cooling fan relay No. 1 ignition feed circuit. After repairs, go to step 14 .
12. Replace cooling fan relay No. 1. After replacing relay, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0480. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 2 CONTROL CIRCUIT (2.4L "N" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The cooling fan is controlled by the Body Function Controller (BFC). BFC sends a Class II message to PCM in order to enable the fans based on various inputs. Ignition voltage travels to all 3 cooling fan relays. PCM provides ground path to relays. When PCM detects that certain DTCs are set, PCM will enable cooling fans.

DTC will set when PCM detects that commanded state of driver and actual state of control circuit do not match.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay on and off. If cooling fan relay No. 2 turns on and off, go to next step. If cooling fan relay No. 2 does not turn on and off, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using DVOM in 10-amp scale, check current from cooling fan relay No. 2 control circuit in PCM connector to ground for 2 minutes. If current draw is less than 0.75 amp, but not zero, go to step 8 . If current draw is not less than 0.75 amp, go to next step.
4. Turn ignition off. Disconnect cooling fan relay No. 2. Check resistance between ground and fan relay No. 2 control circuit at PCM harness connector. If resistance is infinite, go to step 16 . If resistance is not infinite, go to step 14 .
5. Turn ignition off. Disconnect cooling fan relay No. 2. Connect test light between relay No. 2 control terminal and battery feed terminal in relay harness connector. Turn ignition on. Using scan tool, command relay No. 2 on and off. If test light turns on and off with each command, go to step 12 . If test light does not turn on and off, go to next step.
6. Connect test light between ground and relay No. 2 battery feed circuit in harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 15 .
7. Turn ignition off. Reconnect cooling fan relay No. 2. Disconnect PCM harness connector. Turn ignition on. Using a fused jumper wire, connect jumper between ground and cooling fan relay No. 2 control circuit at PCM connector. If relay operates, go to step 13 . If relay does not operate, go to step 14 .
8. Disconnect cooling fan relay No. 2. Using a fused jumper wire, jumper relay No. 2 control circuit to PCM connector ground circuit. If mode control relay turn on, go to next step. If mode control relay does not turn on, go to step 10 .
9. Using DVOM in 10-amp scale, check current at mode control relay control circuit in PCM harness connector terminal for 2 minutes. If current draw is less than 0.75 amp, but not less than zero, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is not less than 0.75 amp, go to step 16 .
10. Turn ignition off. Disconnect mode control relay. Connect test light between mode relay coil terminal in harness connector. Turn ignition on. Connect a fused jumper wire from mode control relay control circuit to ground circuit in PCM harness connector. If test light illuminates, go to step 12 . If test light does not illuminate, go to next step.
11. Using test light connected to ground, probe battery feed circuit in mode control relay connector. If test light illuminates, go to step 14 . If test light does not illuminate, go to step 15 .
12. Check connections at affected relay. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to step 16 .
13. Check connections at PCM. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to step 17 .
14. Repair faulty relay control circuit. After repairs, go to step 18 .
15. Repair faulty relay battery feed circuit. After repairs, go to step 18 .
16. Replace faulty relay. After replacing relay, go to step 18 .
17. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
18. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
19. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 2 CONTROL CIRCUIT (3.1L "W" BODY & 3.4L "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relays No. 2 and 3 on and off. If both relays turn on after several seconds, and then turn off with each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If operation is not as specified, go to next step.
3. Turn ignition off. Disconnect relays No. 2 and 3. Turn ignition on, with engine off. Using a test light connected to ground, probe coil feed circuits for each relay. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 10 .
4. Connect test light between control circuits of each relay and battery feed circuits of each relay. Using scan tool, command relays No. 2 and 3 on and off. If test light turns on after several seconds, and then turns off with each command on both relays, go to step 8 . If test light does not respond as specified, go to next step.
5. If test light remains illuminated with each command when probing either battery feed circuit, go to step 7 . If test light does not remain illuminated with each command when probing either battery feed circuit, go to next step.
6. Check control circuit of each relay for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
7. Check control circuit of each relay for a short to ground. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair battery feed circuit to affected relay. After repairs, go to step 13 .
11. Replace affected relay. After repairs, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0481. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 1 & 2 CONTROL CIRCUIT (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Ignition voltage is supplied directly to Fan Control (FC) relays No. 1 and 2. PCM controls the relays by grounding the control circuit through an internal solid state device called the driver. The driver supplies the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When PCM is commanding a component on, the control circuit should be low (near zero volts). When PCM is commanding a component off, the control circuit should be high (near battery voltage).

If the fault detection circuit senses a voltage other than what is expected, this DTC will set. This DTC will also set when there is a short to ground, open in circuit, or short to battery voltage is detected on control circuit and when condition is present for at least 30 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relay on and off. If cooling fan relays No. 2 and 3 turns on and off, go to next step. If cooling fan relays No. 2 and 3 does not turn on and off, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector. Disconnect cooling fan relays No. 2 and 3. Using a DVOM, check resistance from cooling fan relay control circuit in PCM connector to ground. If resistance reading is infinite, go to next step. If resistance reading is not infinite, go to step 9 .
4. Reinstall cooling fan relay No. 2. Using DVOM in 10-amp scale, check and note current from relay control circuit in PCM harness connector to ground. Remove cooling fan relay No. 2 and install relay No. 3. Note current reading. If current draw is 0.10-0.75 amp for both relays, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is not 0.10-0.75 amp for both relays, go to step 11 .
5. Turn ignition off. Disconnect cooling fan relays No. 2 and 3. Connect test light between relay control terminal and ignition feed terminal in relay harness connector. Turn ignition on. Using scan tool, command relay on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off, go to next step.
6. Connect test light between ground and relay (either one) ignition feed circuit in harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
7. Turn ignition off. Reconnect cooling fan relay. Disconnect PCM harness connector. Turn ignition on. Using a fused jumper wire, connect jumper between ground and cooling fan relay control circuit at PCM connector. If relay operates, go to step 12 . If relay does not operate, go to step 9 .
8. Check connections at cooling fan control relay. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 11 .
9. Repair relay control circuit. After repairs, go to step 14 .
10. Repair ignition feed circuit to relay. After repairs, go to step 14 .
11. Replace affected cooling fan relay. After replacing relay, go to step 14 .
12. Check for poor terminal connection at PCM harness connector. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 2 CONTROL CIRCUIT (3.8L "C", "F" & "G" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command cooling fan relays No. 2 and 3 on and off. If both relays turn on after several seconds, and then turn off with each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If operation is not as specified, go to next step.
3. Turn ignition off. Disconnect relays No. 2 and 3. Turn ignition on, with engine off. Using a test light connected to ground, probe coil feed circuits for each relay. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step 10 .
4. Connect test light between control circuits of each relay and battery feed circuits of each relay. Using scan tool, command relays No. 2 and 3 on and off. If test light turns on after several seconds, and then turns off with each command on both relays, go to step 8 . If test light does not respond as specified, go to next step.
5. If test light remains illuminated with each command when probing either battery feed circuit, go to step 7 . If test light does not remain illuminated with each command when probing either battery feed circuit, go to next step.
6. Check control circuit of each relay for an open or short to voltage. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
7. Check control circuit of each relay for a short to ground. Repair as necessary. After repairs, go to step 13 . If circuits are okay, go to step 9 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 11 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to step 12 .
10. Repair battery feed circuit to affected relay. After repairs, go to step 13 .
11. Replace affected relay. After repairs, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0481. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 2 CONTROL CIRCUIT (3.8L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an output driver module to control ground (control) circuit to cooling fan relay. Output driver module is also used by PCM to diagnose the output of this circuit. If an improper voltage level has been detected on relay control circuit for 30 seconds or more, DTC will set. For duplication of DTC, ensure ignition is on.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Measure voltage between ground and high speed fans control circuit. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 7 .
3. Turn ignition off. Remove cooling fan relays No. 2 and 3. Measure voltage between ground and high speed fans control circuit. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step 6 .
4. Reinstall relays. Turn ignition on. Using DVOM set on 10-amp scale, measure current between ground and high speed fans relay control circuit at PCM harness connector. If current remains 0.1-1.5 amps, go to step 12 . If current does not remain 0.1-1.5 amps, go to next step.
5. Turn ignition off. Remove cooling fan relay No. 3. Turn ignition on. Using DVOM set on 10-amp scale, measure current between ground and cooling fan relay No. 3 control circuit. Monitor current for at least 2 minutes. If current remains 0.1-1.5 amps, go to step 15 . If current does not remain 0.1-1.5 amps, go to step 16 .
6. Repair short to voltage in high speed fans control circuit. After repairs, go to step 18 .
7. Check fuse for battery feed circuit to cooling fan relays No. 2 and 3. If fuse is open, go to next step. If fuse is okay, go to step 9 .
8. Repair short to ground in battery feed circuit to cooling fan relays No. 2 and 3. Replace fuse. After repairs, go to step 18 .
9. Remove cooling fan relay No. 3. Turn ignition on. Measure voltage between ground and battery feed circuit to cooling fan relay No. 3. If voltage is near battery voltage, go to next step. If voltage is not near battery voltage, go to step 14 .
10. Check high speed fans control circuit for an open or short to ground. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to next step.
11. Check control circuit and battery feed circuit for faulty connections at cooling fan relay No. 3 and PCM. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to step 15 .
12. Turn ignition off. Reconnect PCM harness connectors. Remove cooling fan relay No. 3. Turn ignition on. Connect test light between control circuit and ignition feed circuit at cooling fan relay No. 3 harness connector. Using scan tool, command relay on and off. If test light flashes, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If test light does not flash, go to next step.
13. Check high speed fans control circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to step 17 .
14. Repair open in battery feed circuit to cooling fan relays No. 2 and 3 and/or faulty connections between fuse block and fuse for cooling fan No. 2. After repairs, go to step 18 .
15. Replace cooling fan relay No. 3. After repairs, go to step 18 .
16. Replace cooling fan relay No. 2. After repairs, go to step 18 .
17. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
18. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0481. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, system is okay. If scan tool does not indicate that this test ran and passed, go to step 2 .

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0481: COOLING FAN RELAY NO. 2 & 3 CONTROL CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Ignition voltage is supplied directly to cooling fan relay coil. PCM controls relay by grounding control circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when the following conditions are present

1. Engine speed greater than 600 RPM.
2. Ignition voltage between 6-16 volts.
3. PCM detects commanded state of driver and actual state do not match.
4. Conditions met for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If complaint is that fans are on all time, go to next step. If complaint is that fans are not on all time, go to step 4 .
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. If fans are on, go to step 7 . If fans are not on, go to step 10 .
4. Turn ignition off. Remove cooling fan relays No. 2 and 3. Connect a test light between ground and relay No. 2 coil terminal in relay harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
5. Turn ignition off. Reinstall both relays. Disconnect PCM harness connector. Connect test light between ground and relay No. 2 and 3 control circuit at PCM connector. If test light illuminates, go to step 9 . If test light does not illuminate, go to next step.
6. Repair open circuit between PCM and splice. After repairs, go to step 11 .
7. Repair short to ground in relay No. 2 and 3 control circuit. After repairs, go to step 11 .
8. Repair short to battery voltage in relay No. 2 and 3 control circuit. After repairs, go to step 11 .
9. Check connections at PCM. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
11. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0481. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
12. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT-NO SIGNAL (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Vehicle speed values are provided by the Vehicle Speed Sensor (VSS). The sensor is mounted on the differential area of the transaxle housing. The PM generator produces a pulsing voltage whenever vehicle speed is greater than 3 MPH. These pulses occur 16 times per each revolution of the differential housing and are translated to provide vehicle speed in miles per hour.

DTC will set if there is VSS signal when engine speed is between 1400-4000 RPM, MAP sensor indication is less than 0.5 volt (3 psi) for greater than 5 seconds or vehicle not in Park/Neutral (A/T). VSS signal is continuously checked once these conditions are met. If VSS signal is missing, speedometer will be inoperative.

1. Install scan tool. Raise and support drive wheels. Start engine. Rotate drive wheels at greater than 3 MPH. If scan tool reads a speed, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not read a speed, go to next step.
2. Turn engine off. Disconnect PCM harness connector J3. Using a DVOM, check resistance between VSS harness connector terminals at PCM. Resistance should be between 800-1600 ohms. If resistance is as specified, go to next step. If resistance is not as specified, go to step 4 .
3. Check VSS tightness. Tighten to 20 ft. lbs. (26 N.m) and retest. If sensor is tight, check for terminal tightness or faulty PCM.
4. Disconnect VSS harness connector. Check resistance between sensor terminals. Resistance should be 800-1600 ohms. If resistance is not as specified, replace faulty VSS. If resistance is as specified, check for open or short in circuits between VSS and PCM.

When diagnosing an intermittent problem, use scan tool to review malfunction history diagnostic information. This data can be used to duplicate a problem.

The speedometer will not work if the VSS sub-system has failed. VSS resistance should be between 800-1600 ohms. If problem is intermittent, wiggle wires while monitoring VSS signal on scan tool and watch for signal to jump or go away. PCM will calculate VSS based on RPM and TP sensor signal if DTC P0500 is present, but speedometer will remain inoperative.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Processed wheel speed sensor signal is sent from Electronic Brake and Traction Control Module (EBTCM) through theft deterrent module to ECM. The ECM calculates vehicle speed from this signal. This DTC is capable of diagnosing circuit faults between theft deterrent module and ECM only. Circuit faults between EBCM and theft deterrent module are diagnosed by ABS controller diagnostics.

If vehicle speed signal is less than 12 MPH for more than one second, DTC will set. For duplication of DTC, ensure fuel cut-off is enabled, engine speed is 1800-2200 RPM, and engine coolant temperature is greater than 149°F (65°C).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise drive wheels. Start engine. Turn off traction control system (if equipped). Allow engine to idle in gear. Monitor vehicle speed using scan tool. If vehicle speed is greater than zero MPH, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If vehicle speed is not greater than zero MPH, go to next step.
3. Turn ignition off. Disconnect ECM harness connectors. Using a test light connected to battery positive, probe vehicle speed/theft deterrent signal circuit at ECM harness connector. Leave test light connected. Using DVOM set to AC/Hz, 4-volt scale, measure voltage between ground and vehicle speed/theft deterrent signal circuit at ECM harness connector. While monitoring DVOM, turn ignition on, with engine off. If 100-900 Hz is momentarily indicated, go to step 5 . If indicated value is not as specified, go to next step.
4. Turn ignition off. Disconnect theft deterrent module harness connector. Check vehicle speed/theft deterrent signal circuit for an open, short to ground or short to power. If a problem is found, go to step 6 . If circuit is okay, go to step 7 .
5. Turn ignition off. Reconnect ECM. Disconnect theft deterrent module harness connector. Connect Signal Generator Tester (J-38522) to vehicle speed signal circuit at theft deterrent module harness connector. Connect one terminal to signal circuit and other terminal to ground. Turn ignition on. Turn tester on and set tester to 12-volt, 50 percent duty cycle and 600 Hz. If scan tool indicates a vehicle speed greater than zero MPH, perform ABS diagnostic system check. See appropriate ANTI-LOCK article in BRAKES. If scan tool does not indicate a vehicle speed greater than zero, go to step 8 .
6. Repair vehicle speed/theft deterrent signal circuit between theft deterrent module and ECM. After repairs, go to step 10 .
7. Check for faulty harness connections at theft deterrent module. Repair as necessary. After repairs, go to step 10 .
8. Check for faulty harness connections at ECM. Repair as necessary. After repairs, go to step 10 . If connections are okay, go to next step.
9. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code currently on vehicle. After repairs, go to next step.
10. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0500. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

For any test that requires probing ECM or component harness connectors, use Connector Test Adapter Kit (J-35616-A). This will prevent damage to harness connector terminals. Check for the following conditions

Check for poor connections at ECM or at component. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.

Check for misrouted wiring harness. Inspect harness to ensure that it is not routed too close to high voltage wires (spark plug wires) or too close to high current devices (generator, motors, solenoids).

Check for damaged wiring harness. If harness appears to be okay, observe scan tool while moving related connectors and wiring harnesses. A change in scan tool display may help to locate fault.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (3.8L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Vehicle Speed Sensor (VSS) supplies vehicle speed information to PCM. VSS is a magnetic induction type. Gear teeth pressed on outside of output shaft induce a frequency signal in sensor as shaft rotates. Signal goes directly to PCM. PCM uses pulsed signal to calculate vehicle speed based on time between pulses.

Conditions required to test for DTC are

1. Engine speed greater than 600 RPM.
2. Vehicle in gear.
3. Conditions present greater than 2 seconds.
4. VSS indicates a speed of greater than 3 MPH for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support vehicle. Start engine and idle in gear. Using scan tool, read VSS SIGNAL. If scan tool displays greater than zero MPH, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool displays zero MPH, go to next step.
3. With engine still idling in gear, observe speedometer. If speedometer displays greater than zero MPH, go to step 7 . If speedometer displays zero MPH, go to next step.
4. Turn ignition off. Connect Signal Generator (J33431-B) to VSS harness connector. Turn ignition on. Turn signal generator on. If scan tool displays greater than zero MPH, go to step 6 . If scan tool does not display zero MPH, go to next step.
5. Turn ignition off. Disconnect PCM harness connectors. Check VSS harness connector signal and ground circuits for open or shorts. Repair as necessary. After repairs, go to step 8 . If no problem is found, go to step 7 .
6. Replace VSS. After replacing sensor, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Turn ignition off. Raise and support vehicle. Start engine and idle in gear. Using scan tool, read VSS SIGNAL. If scan tool displays greater than zero MPH, repair is complete. If scan tool displays zero MPH, return to step 3 .

Check for faulty connection at VSS and PCM connectors. Check for damaged harness. Check for loose or damaged VSS rotor.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Vehicle Speed Sensor (VSS) circuit is a magnetic induction type sensor. Gear teeth pressed on outside diameter of output shaft assembly induce an alternating current in sensor as shaft rotates. Signal goes directly to VCM. Pulsing action takes place about 40 times per revolution of output shaft of transmission and VCM will calculate vehicle speed based on time between pulses.

Conditions for setting DTC

1. No MAP sensor DTCs are set.
2. Vehicle speed less than one MPH.
3. Throttle angle less than 3 percent.
4. ECT greater than 140°F (60°C).
5. Engine speed 1400-4400 RPM.
6. MAP pressure less than 20 kPa.
7. Conditions are met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Clear DTCs. Using Connector Test Kit (J-35616-A), backprobe signal and ground circuits of VSS connector. Raise vehicle wheels and place engine in operating gear. Check voltage with voltmeter on 200-volt AC scale. If voltage reading is constant, go to step 5 . If voltage reading is not constant, go to next step.
3. If voltage varies, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If voltage does not vary, go to next step.
4. If voltmeter indicates no voltage, go to step 11 . If voltmeter does not indicate no voltage, go to step 12 .
5. Turn ignition off. Disconnect VSS connector. With vehicle still raised, engine operating, transmission in gear and voltmeter on 200-volt AC scale, check voltage between VSS connector terminals. If voltage varies with RPM, go to step 7 . If voltage does not vary with RPM, go to next step.
6. Replace VSS. After replacing sensor, go to step 12 .
7. Check for poor connections at VCM and VSS. If a problem is found, go to step 9 . If no problem is found, go to next step.
8. Check for open or short in VSS signal and ground circuits. If a problem is found, go to step 10 . If no problem is found, go to step 12 .
9. Repair connections. After repairs, go to step 12 .
10. Repair open or short. After repairs, go to step 12 .
11. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
12. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
13. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for proper calibration of speedometer.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Vehicle Speed Sensor (VSS) is a magnetic induction type. Gear teeth pressed on outside of output shaft induce an AC current in sensor as shaft rotates. Signal goes directly to VCM. VCM uses pulsed signal to calculate vehicle speed based on time between pulses.

Conditions for setting DTC

1. No MAP DTCs set.
2. Throttle angle less than 3.125 percent.
3. ECT greater than 140°F (60°C).
4. Engine speed 1400-4400 RPM.
5. MAP less than 20 kPa.
6. Conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, clear DTCs. Using Connector Test Adapter Kit (J-35616-A) and a DVOM set to AC 200 volt scale, backprobe across VSS harness connector signal and ground circuits. Raise and support vehicle. Start engine and place transmission in gear. If voltage is constant, go to step 5 . If voltage is not constant, go to next step.
3. If voltage varies, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If voltage does not vary, go to next step.
4. If scan tool displays NO VOLTAGE, go to step 11 . If scan tool does not display NO VOLTAGE, go to step 12 .
5. With vehicle still raised, disconnect VSS connector. With engine running, place transmission in gear. Using a DVOM on 200-volt AC scale, check voltage across signal and ground circuits at VSS. If voltage varies with RPM, go to step 7 . If voltage does not vary with RPM, go to next step.
6. Replace VSS. After replacing sensor, go to step 12 .
7. Check for faulty connection at VCM and VSS connector. If faulty connection is found, go to step 9 . If connections are okay, go to next step.
8. Check for open or short in ground and signal circuits between VCM and VSS. If problem is found, go to step 10 . If no problem is found, go to step 12 .
9. Repair connection as necessary. After repairs, go to step 12 .
10. Repair open or short as necessary. After repairs, go to step 12 .
11. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
12. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0500. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2 .
13. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Ensure VCM is properly calibrated for vehicle speedometer.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A toothed wheel mounted on output shaft of transmission generates an AC voltage pulse as it moves past Vehicle Speed Sensor (VSS). VSS contains a permanent magnet surrounded by a coil of wire, which produces a magnetic field. As toothed ring interrupts magnetic field, an AC pulse is generated. As vehicle speed increases, AC voltage pulse also increases.

DTC will set when PCM detects vehicle speed at zero MPH for 100 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support vehicle. Disable ASR/TCS system (if equipped). Start engine. With engine at idle, place transmission in 3rd gear and slowly release clutch. Slowly bring engine speed to 1500 RPM. Hold speed. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than 15 MPH, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If displayed vehicle speed is not greater than 15 MPH, go to next step.
3. Turn ignition off. Disconnect VSS harness connector. Install jumpers from Connector Kit (J-33431-B) to VSS sensor. Using DVOM in AC scale, connect DVOM negative lead to pin "A" to VSS and DVOM positive lead to pin "B" of VSS. Start and operate engine at idle. Place transmission in 2nd gear and release clutch. Slowly bring engine speed to 1500 RPM. Hold speed. Check voltage reading at DVOM. If voltage reading is 1.2 volts or greater, go to next step. If voltage reading is not 1.2 volts or greater, go to step 9 .
4. Turn ignition off. Using a test light connected to battery voltage, probe VSS terminal "A" (low signal circuit). If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
5. Turn ignition off. Disconnect PCM harness connector C2. Turn ignition on. Check voltage between ground and VSS high signal circuit. If voltage reading is greater than 0.2 volt, go to step 7 . If voltage reading is not greater than 0.2 volt, go to next step.
6. Check VSS high signal circuit for open or short to ground. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 11 .
7. Repair short to voltage on VSS high signal circuit. After repairs, go to step 12 .
8. Repair open or high resistance in VSS high signal circuit. After repairs, go to step 12 .
9. Inspect reluctor wheel on transmission output shaft for damage before replacing VSS sensor. Replace VSS. After replacing sensor, go to step 12 .
10. Repair open in VSS low circuit. After repairs, go to step 12 .
11. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0500. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If all circuits to PCM and VSS have been thoroughly checked, check terminal connections at VSS harness connector and at PCM harness connector. If terminals and connectors are okay, replace PCM.

DTC P0500: VEHICLE SPEED SENSOR (VSS) CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A toothed wheel mounted on output shaft of transmission generates an AC voltage pulse as it moves past Vehicle Speed Sensor (VSS). VSS contains a permanent magnet surrounded by a coil of wire, which produces a magnetic field. As toothed ring interrupts magnetic field, an AC pulse is generated. As vehicle speed increases, AC voltage pulse also increases.

DTC will set when the following conditions are present

1. DTCs P0107, P0108, P0117, P0118, P0121, P0122, P0123, P0125, P0506 and P0507, P1120, P1220 or P1221 not set.
2. Engine coolant temperature greater than 95°F (35°C).
3. Engine speed greater than 1000 RPM.
4. On "F" Body, TP sensor angle greater than 5 percent.
5. On "Y" Body, TP sensor angle greater than 10 percent.
6. MAP between 40-100 kPa with A/C off.
7. MAP between 45-100 kPa with A/C on.
8. Conditions met for 2 seconds.
9. PCM detects vehicle speed at zero MPH for 50 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support drive axles. Disable ASR/TCS system (if equipped). Start engine. With engine at idle, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If displayed vehicle speed is zero MPH, go to next step.
3. Turn ignition off. Disconnect VSS harness connector. Connect Signal Generator Tester (J-33431-B) to VSS harness. Turn ignition on. Set tester to generate VSS signal. Using scan tool, monitor displayed vehicle speed. If displayed vehicle speed is greater than zero MPH, go to next step. If displayed vehicle speed is zero MPH, go to step 5 .
4. Replace faulty VSS harness connector or faulty VSS. After repairs, go to step 12 .
5. Using DVOM, check voltage between VSS signal circuit to chassis ground. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 9 .
6. Using DVOM, check voltage between VSS signal circuit to VSS ground circuit. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 10 .
7. Check vehicle calibration code. If calibration is correct, go to next step. If calibration is incorrect, go to step 11 .
8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to step 12 .
9. Repair signal circuit to VSS. After repairs, go to step 12 .
10. Repair ground circuit to VSS. After repairs, go to step 12 .
11. Install proper or most current calibration code. After entering calibration code, go to next step.
12. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0500. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
13. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If all circuits to PCM and VSS have been thoroughly checked, check terminal connections at VSS harness connector and at PCM harness connector. If terminals and connectors are okay, replace PCM.

DTC P0502: VEHICLE SPEED SENSOR (VSS) CIRCUIT-LOW INPUT-MANUAL TRANSAXLE (2.2L "J" BODY & "S" SERIES & 2.4L "J" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Vehicle Speed Sensor (VSS) is a permanent magnet generator that is mounted on transaxle. VSS produces a pulsing voltage whenever vehicle speed is greater than 3 MPH. A/C voltage and number of pulses increases with vehicle speed. Powertrain Control Module (PCM) then supplies VSS signal to instrument cluster for speedometer, odometer, electronic transaxle (if equipped) and cruise control operation.

Conditions for setting DTC

1. Vehicle speed is less than 2 MPH.
2. Engine speed is 1700-3600 RPM.
3. TP angle 8-20 percent.
4. Engine vacuum between 80-70 kPa.
5. Conditions met for 5 seconds.
6. DTCs P0107, P0108, P0122 and P0123 not set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support drive axles. Start engine. With engine at idle, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to next step. If displayed vehicle speed is zero MPH, go to step 4 .
3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME data and note parameters. Start engine and operate vehicle within conditions required for setting this DTC, and as close to conditions recorded in FREEZE FRAME as possible. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, go to step 12 . If displayed vehicle speed is zero MPH, go to next step.
4. Disconnect PCM harness connectors. Connect DVOM between VSS terminals. Rotate drive wheel by hand and note A/C voltage reading. If voltage reading is 0.5 volt or greater, go to next step. If voltage reading is not 0.5 volt or greater, go to step 7 .
5. Check vehicle calibration code. If calibration is correct, go to step 13 . If calibration is incorrect, go to next step.
6. Install proper or most current calibration code. After entering the calibration code, go to step 14 .
7. Ensure ignition is off. Check resistance between VSS terminals. If resistance is greater than 1950 ohms, go to next step. If resistance is not greater than 1950 ohms, go to step 9 .
8. Check for an open in VSS signal circuit. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to step 11 .
9. If resistance reading in step 7 is 1300-1950 ohms, go to next step. If resistance is not 1300-1500 ohms, go to step 11 .
10. Check for short to ground in VSS signal circuit. Also, check if VSS circuits are shorted together. Repair circuits as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
11. Remove VSS. Check resistance between VSS terminals. If resistance is 1300-1950 ohms, go to step 13 . If resistance is not 1300-1950 ohms, go to next step.
12. Replace VSS. After replacing sensor, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
15. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Scan tool should indicate vehicle speed whenever drive wheel is turning at greater than 3 MPH. A DTC P0502 can falsely set if engine is "brake torqued" in gear. Disregard DTC if set while drive wheel is not turning. An intermittent problem can be caused by a poor connection, rubbed through wire insulation or broken wire inside insulation. Thoroughly check VSS circuits.

DTC P0506 OR P0507: RPM OUT OF RANGE-LOW OR HIGH (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The Idle Air Control (IAC) valve consists of a 2 coil stepper motor controlling a pintle. PCM pulses a signal to the IAC valve by switching the high and low side circuits, depending on which direction the pintle needs to move. The amount of movement being commanded is displayed in counts on scan tool. With engine off, IAC pintle is retracted (80-100 counts) allowing maximum air during a restart. After start-up, the motor position commanded is based on coolant temperature and TP sensor values.

DTC P0506 (Idle RPM Too Low) will set when RPM is too low and PCM has commanded the IAC valve open and the actual RPM is greater than 100-300 RPM of the desired RPM. Amount of RPM error allowed depends on ECT.

DTC P1508 (IAC Valve Closed) may set along with P0506 if the intrusive test indicates that the valve is stuck in an open position.

DTC P1509 (IAC Valve Open) may set along with P0507 is the intrusive test indicates that the valve is stuck in a closed position.

IAC is continuously checked with engine is running and PCM in idle control.

1. Warm engine to normal operating temperature (greater than 176°F). Install scan tool. Using scan tool, extend and retract IAC pintle while observing RPM change. If RPM changes, go to next step. If RPM does not change, go to step 4 .
2. Exit scan tool control. Monitor actual RPM and desired RPM. If actual RPM is within 100 RPM of desired RPM, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If actual RPM is not within 100 RPM of desired RPM, go to next step.
3. If idle is too high, use scan tool to determine RPM is at idle command. If not at idle command, check TP sensor throttle linkage including cruise control adjustment (if equipped). If linkages are okay, check for vacuum leak. If idle is too low, check accessory drive components or causes of unstable/rough running.
4. Turn ignition off. Disconnect IAC valve. Turn ignition on. Using scan tool, cycle valve from open to closed using the position control feature of the scan tool. While commanding motor position open and closed, probe each IAC connector pin with a test light connected to ground, then test again with test light connected to battery voltage. Go to next step.
5. With test light connected to ground, test light should blink when connected to IAC terminals "A" and "C", then turn off. With test light connected to battery voltage, test light should blink and then stay on steady. With test light connected to ground, test light should blink and then stay on steady when connected to IAC terminals "B" and "D". With test light connected to battery voltage, test light should blink and then turn off. If all 4 circuits tested properly, go to next step. If not all 4 circuits tested properly, go to step 7 .
6. Check for terminal tightness at harness connectors. If terminals are okay, check for faulty IAC valve.
7. If test light stayed on steady when it should be off, check for shorted circuit to battery voltage. Repair as necessary. If circuit is okay, go to next step. If test light does not turn on when it should be on, check circuits for open or shorted to ground. Repair as necessary. If circuits are okay, go to next step.
8. If all circuits are okay, disconnect PCM harness connector J2. Check resistance between all possible combinations of 2 circuits (i.e., terminals "A" to "B" or terminals "C" to "D"). If resistance reading is less than 2 ohms (open circuit), repair circuits shorted together. If resistance is 2 ohms or greater, check terminal tightness to harness connectors. If terminals are okay, replace faulty PCM.

At normal operating temperature, idle must be within 100 RPM of desired RPM or DTC P0506 or P0507 will set. The malfunction history will store the desired RPM as well as the actual RPM at the time DTC is set.

If either DTC P0506 or P0507 becomes active during a drive cycle, PCM will run an intrusive test if vehicle is at steady throttle cruise of 20-40 MPH with airflow between 4-10 gm/s. When these conditions are met, PCM will issue a motor move command while monitoring MAP sensor value.

If no MAP sensor change is detected during the intrusive test, the high and low idle conditions detected is probably due to an IAC valve circuit problem. The scan tool's idle control table will indicate if an intrusive test has ever been performed since the codes were cleared. If an idle problem is detected and PCM never ran an intrusive test, the IAC circuit must be checked for proper operation.

IAC terminal resistance between terminals "A" to "B" and "C" to "D" should be 40-80 ohms. Terminals "A" to "C", "A" to "D", "B" to "C" and "B" to "D" should be infinite (open).

DTC P0506: IAC SYSTEM RPM LOW (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which can vary depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

Conditions for setting this DTC are as follows

1. DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0123, P0125, P0131, P0132, P0133, P0134, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0341, P0342, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P0502, P0506, P0601, P0602, P0705, P1133, P1404 and P1441 not set.
2. IAC valve counts are greater than 145.
3. BARO is greater than 72 kPa.
4. ECT greater than 104°F (40°C).
5. Engine run time greater than 20 seconds.
6. Idle speed is less than 100 RPM of desired RPM for greater than 19 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Ensure engine is at normal operating temperature, transmission is in Park or Neutral, parking brake is set and A/C is off. Using scan tool, command IAC valve from 900-2000 RPM. If engine RPM changes smoothly, go to next step. If engine RPM does not change smoothly, go to step 5 .
3. Turn ignition off. Disconnect IAC valve harness connector. Remove IAC valve. Check resistance IAC windings between IAC valve terminals "A" and "B", and then terminals "C" and "D". If each reading is 40-80 ohms, go to next step. If one or both readings are not 40-80 ohms, go to step 13 .
4. Check resistance between IAC valve terminals "B" and "C", and then between terminals "A" and "D". If each reading is infinite, go to step 15 . If one or both readings are not infinite, go to step 13 .
5. Turn ignition on, with engine off. Disconnect IAC valve harness connector. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 terminals, go to next step. If test light does not illuminate on 2 terminals, go to step 7 .
6. With test light connected to positive battery terminal, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 terminals, go to step 8 . If test light does not illuminate on 2 terminals, go to step 9 .
7. Check for an open or short to ground in IAC valve low and high circuits. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 10 .
8. Start engine and allow it to idle. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light flashes on and off for all 4 terminals, go to step 11 . If test light does not flash on and off for all 4 terminals, go to step 12 .
9. Check for an open or short to voltage in IAC valve low and high circuits. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to next step.
10. Check PCM connector for poor terminal connections. Repair as necessary. After repairs, go to step 15 . If connector is okay, go to step 14 .
11. Inspect IAC valve passages. Repair as necessary. After repairs, go to step 15 . If IAC passages are okay, go to step 13 .
12. If test light remained on constantly for terminals that did not flash in step 8 , go to step 9 . If test light did not remain on constantly for terminals that did not flash, go to step 7 .
13. Replace IAC valve. After replacing IAC valve, go to step 15 .
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0506. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
16. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

Inspect IAC valve connector for proper connection. Inspect throttle stop screw for signs of tampering. Inspect throttle linkage for signs of binding or excessive wear. A slow or unstable idle may be caused by one of the following

1. Fuel system too rich or too lean.
2. Foreign material in throttle body bore or in air induction system.
3. Leaking or restricted intake manifold.
4. Excessive engine overloading.
5. Engine oil viscosity it too high.

DTC P0506: IDLE SPEED LOW (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

IAC system controls idle speed by allowing a controlled amount of air to by-pass throttle blade via a passage in IAC valve. ECM controls IAC system to maintain a desired idle speed. Speed may vary depending on input to ECM and other criteria. If ECM detects engine speed is outside IAC system's range of control at idle, this DTC will set.

Conditions required to set DTC are

1. Actual engine RPM is less than desired idle speed by at least 100 RPM.
2. Short term air trim is greater than 5.6 gm/s.
3. Conditions are met for greater than 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Load engine by turning on several accessories (A/C, headlights, rear defogger, etc.). If actual engine speed is not greater than 200 RPM or less than 100 RPM of desired idle speed, fault is not present. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If actual engine speed is greater than 200 RPM or less than 100 RPM of desired idle speed, go to next step.
3. If engine RPM is too high, go to next step. If engine RPM is not too high, go to step 5 .
4. Check for vacuum leaks, throttle blade not closing properly, faulty PCV system or mechanical IAC valve failure. Repair component as necessary. After repairs, go to step 6 .
5. Check for excessive deposits in throttle body or IAC valve passages. Check for kinked or obstructed IAC air supply hose. Inspect for IAC valve mechanical failure. Check for parasitic load on engine (transmission problem, belt driven accessory problem, etc.). Check for mechanical engine problem. Repair as necessary. After repairs, go to next step.
6. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Operate vehicle within conditions for this DTC to set. Check for DTCs. If DTC P0506 is set, go to step 2 . If DTC P0506 is not set, go to next step.
7. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

For any test that requires probing ECM or component harness connectors, use Connector Test Adapter Kit (J-35616-A). This will prevent damage to harness connector terminals. Check for the following conditions

Check for poor connections at ECM or at component. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.

Check for damaged wiring harness. If harness appears to be okay, observe scan tool while moving related connectors and wiring harnesses. A change in scan tool display may help to locate fault.

DTC P0506: IDLE CONTROL SYSTEM-LOW RPM (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

Conditions required to set DTC are

1. No CKP, ECT, IAT, MAF, MAP, TP, VSS sensor DTCs set.
2. No EVAP solenoid, EVAP system, fuel trim, fuel injector, EGR flow or EGR pintle position DTCs set.
3. ECT greater than 122°F (70°C).
4. Engine running at least 2 minutes.
5. Vehicle speed less than 3 MPH.
6. IAT greater than 0°F (-18°C).
7. Throttle closed.
8. Engine speed greater than 175 RPM lower than desired idle.
9. BARO greater than 65 kPa.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If ENGINE SPEED is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not off as RPM changes from 650-1500 RPM. If lights flash as specified, go to step 6 . If lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and IAC "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, repair is complete. If ENGINE SPEED is not as specified, return to step 2 .

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

DTC P0506: IDLE CONTROL SYSTEM-LOW RPM (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM. PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

DTC will set when engine speed is over 100 RPM less than desired idle. DTC will also set when, there is no fuel injector faults, misfire, fuel trim, CKP, ECT, EVAP, EGR, VSS, TP, IAT, MAP or MAF sensor DTCs set, BARO is greater than 65 kPa, engine running for at least 3 minutes, system voltage 9-18 volts, ECT greater than 158°F (70°F), vehicle speed is less than 3 MPH, IAT is greater than 0°F (-18°C) or when throttle is closed.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. If engine speed remains within 50 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If engine speed is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027-A) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not off as RPM changes from 650-1500 RPM. If lights flash as specified, go to step 6 . If lights are not flashing as specified, go to next step.
5. Check IAC "A" high and low, and IAC "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If engine speed remains within 100 RPM of desired RPM for each command, go to next step. If engine speed is not as specified, return to step 2 .
12. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, go to applicable DTC test. If no other DTCs are present, system is okay.

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

DTC P0506: IAC SYSTEM-LOW RPM (3.8L "C", "F", "G", "H" & "W" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

Conditions required to set DTC are

1. No CKP, ECT, IAT, MAF, MAP, TP or VSS sensor DTCs set.
2. No EVAP solenoid, EVAP system, fuel trim, fuel injector, EGR flow or EGR pintle position DTCs set.
3. ECT greater than 158°F (70°C).
4. Engine running greater than 5 seconds.
5. Vehicle speed less than 3 MPH.
6. IAT greater than -4°F (-20°C).
7. Throttle closed.
8. Engine speed greater than 175 RPM lower than desired idle.
9. Conditions present for greater than 15 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor engine speed and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If engine speed remains within 100 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If engine speed is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not off as RPM changes from 500-1500 RPM. If lights flash as specified, go to step 6 . If lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and IAC "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. If faulty connection is found, repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor engine speed and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If engine speed remains within 100 RPM of desired RPM for each command, repair is complete. If engine speed is not as specified, return to step 2 .

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

DTC P0506: IAC SYSTEM-LOW RPM (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This test determines if idle control system is maintaining the proper idle speed. The IAC system controls idle speed by allowing a certain amount of air to bypass the throttle body (throttle plate closed during idle) through the IAC valve. The PCM controlled IAC motor moves a pintle in and out of IAC valve, varying the amount of air entering the intake manifold. DTC will set when engine idle speed is less than 80 RPM or greater than the desired idle speed for 15 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, check if other DTCs are present. If other DTCs are present, diagnose affected DTCs first. If other DTCs are not present, go to next step.
3. Start and idle engine. Turn off all accessories. Using scan tool, select MISC TESTS and select IAC SYSTEM. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring ENGINE SPEED display. If ENGINE SPEED display remains within 50 RPM of desired value for each RPM command, fault is not present. If engine speed is not within 50 RPM of desired value, go to next step.
4. Disconnect IAC valve. Install IAC Noid Light (J-37027). Start engine. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring noid light. If noid light cycles Red and Green (never off), go to step 6 . If noid light does not cycle, go to next step.
5. Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 9 .
6. Check throttle body for objects blocking IAC passage or throttle bore, excessive deposits in IAC passage, pintle, throttle bore or throttle plate. Check for restriction or vacuum leaks in air intake system. Check adjustment screw for tampering. Repair as necessary. If no problems are found, go to next step.
7. Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
8. Replace IAC valve.
9. Check IAC terminal contacts at PCM harness connector C1. Repair as necessary. If terminal contacts are okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment.

DTC P0506: IDLE CONTROL SYSTEM-LOW RPM (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM controls idle speed with an Idle Air Control (IAC) valve to a calculated desired RPM based on sensor inputs and actual engine RPM. VCM uses 4 circuits to move an IAC valve, allowing varying amounts of airflow into intake manifold.

To increase idle RPM, VCM moves IAC valve out, allowing more air to by-pass throttle plate. To decrease RPM, VCM moves IAC valve in, reducing amount of air by-passing throttle plate. Scan tool reads VCM commands to IAC valve in counts. The higher the counts, the more air that is allowed to by-pass throttle plate (higher idle). The lower the counts, less air is allowed to by-pass throttle plates (lower idle).

Conditions for setting DTC

1. No ECT, MAP, TP or VS sensor DTCs are set.
2. ECT greater than 162°F (72°C).
3. IAT greater than -13°F (-25°C).
4. BARO greater than 70 kPa (less than 10,300 ft.).
5. Vehicle speed less than 2 MPH.
6. System voltage greater than 10 volts but less than 18 volts.
7. Engine run time greater than 30 seconds.
8. Throttle position less than 1 percent.
9. Conditions are met for greater than 3 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Install scan tool. Check if any other DTCs are set. If other DTCs are not set, go to next step. If other DTCs are set, go to that DTC test.
3. Check if DTC P0506 is active this ignition cycle. If DTC P0506 is active this ignition cycle, go to step 5 . If DTC P0506 is not active this ignition cycle, go to next step.
4. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Problem is engine mechanical related. Repair as necessary. After repairs, go to next step.
6. Using scan tool, clear codes. Start engine. Idle at operating temperature. Select SPECIFIC DTC for this DTC. Operate vehicle under conditions which originally set DTC. If scan tool indicates DTC test has run and passed, go to next step. If not, go to step 2 .
7. Using scan tool, select CAPTURE INFO function. Review stored info. If other DTCs are stored, go to applicable DTC. If no other DTCs are stored, system is okay.

DTC could be caused by an IAC valve which is stopped and cannot respond to VCM, a throttle stop screw which has been tampered with, or a damaged throttle or linkage.

A slow, unstable or fast idle could be caused by a non-IAC valve system problem that cannot be overcome by IAC valve. See appropriate TROUBLE SHOOTING - NO CODES article. Out of range control IAC scan tool counts will be greater than 60 if idle is too low and zero if idle is too high. Check for fuel system too lean and rich. Check throttle body bore for foreign material. IAC reset is done with scan tool miscellaneous functions mode.

DTC P0506: IDLE CONTROL SYSTEM-LOW RPM (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. VCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

VCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

Conditions for setting DTC

1. No ECT, MAP, TP or VSS sensor DTCs set.
2. ECT greater than 122°F (50°C).
3. IAT greater than -13°F (-25°C).
4. BARO greater than 10.2 psi (0.72 kg/cm 2 ) at 10,300 ft.
5. Vehicle speed less than 2 MPH.
6. Throttle angle at less than 1 percent.
7. Engine running greater than 30 seconds.
8. Conditions met for greater than 3 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs. If no other DTCs are set, go to next step.
3. If DTC P0506 is active in this ignition cycle, go to step 5 . If DTC is not active in this ignition cycle, go to next step.
4. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Repair engine mechanical problem. After repairs, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool indicates that this test RAN AND PASSED, go to next step. If scan tool does not indicate that this test RAN AND PASSED, repeat step 2 .
7. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Reset IAC using scan tool MISC FUNCTIONS. Check if fuel system is running too rich or too lean. Inspect throttle body bore for foreign material.

DTC P0506: IDLE SPEED LOW (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. If PCM detects that idle speed is out of IAC systems range of control at idle, it will perform an active test while vehicle is being driven.

DTC will set when actual idle speed is 100 RPM less than desired speed for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM from 500 RPM up to 1500 RPM, then from 1500 RPM to 500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM did not respond to within 100 RPM of each command, go to next step.
3. If engine RPM is greater than 100 RPM of desired RPM, go to next step. If RPM is not greater than 100 RPM of desired RPM, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 13 . If no problems were found, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to step 13 . If no problems were found, go to next step.
6. Turn ignition off. Disconnect IAC harness connector and install IAC Noid Light (J-37027-A). Start and operate engine at idle. Using scan tool, command RPM up to 1500 RPM, down to 500 RPM and up to 1500 RPM. Observe noid light. If both LEDs on noid light cycle Red and Green, but never off, go to next step. If both LEDs on noid light does not cycle Red and Green, go to step 8 .
7. Turn ignition off. Remove IAC valve. Connect IAC valve to IAC Driver Tool (J-37027-A). Hold IAC valve pintle with finger to prevent pintle from dropping. Using IAC driver, retract and extent pintle. If pintle moves steadily with each flash of the IAC driver light, go to step 9 . If pintle does not move steadily with each flash of the IAC driver light, go to step 10 .
8. Check IAC circuit for poor connections, open circuit, or short to ground or voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 11 .
9. Inspect IAC passages for blockage or heavy deposits. Clean passages as necessary. After cleaning passages, go to step 13 .
10. Replace IAC valve. After replacing IAC valve, go to step 13 .
11. Check for poor connections at PCM terminals. Repair as necessary. After repairs, go to step 13 . If terminal connections are okay, go to next step.
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0506: IDLE SYSTEM LOW (5.7L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. DTC P0506 will set if PCM detects that idle speed is out of IAC systems range of control at idle.

DTC will set when the following conditions are present

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0220, P0300, P0401, P0404, P0405, P0443, P0500-P0503 or P1441 are not set.
2. Engine running for more than 60 seconds.
3. Engine coolant temperature is greater than 140°F (60°C).
4. IAT greater than 14°F (-10°C).
5. BARO greater than 65 kPa.
6. Ignition voltage 9-18 volts.
7. Vehicle speed less than one MPH.
8. Actual idle speed is 100 RPM less than desired idle speed.
9. Above conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM from 500 RPM up to 1500 RPM, then 1500 RPM to 500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM does not respond as commanded, go to next step.
3. If engine speed is more than 100 RPM greater than desired RPM, go to next step. If engine speed is not as specified, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
6. Turn ignition off. Disconnect IAC harness connector. Install appropriate IAC test light (included in Kit J-37027-A). Start engine and allow it to idle. Using scan tool, command RPM up to 1500 RPM, down to 500 RPM, and then up to 1500 RPM while observing test light. If both LEDs cycle Red and Green, but never OFF, go to next step. If test light does not react as specified, go to step 8 .
7. Turn ignition off. Remove IAC valve. Connect IAC valve to IAC driver tool (included in Kit J-37027-A). Hold IAC valve with a finger over pintle to prevent overextension. Using driver tool, retract and extend pintle. If pintle moves steadily with each flash of test light, go to step 9 . If operation is not as specified, go to step 10 .
8. Check IAC harness for faulty connections, shorts to battery voltage or ground, or opens. Repair as necessary. After repairs, go to step 13 . If harness is okay, go to step 11 .
9. Check IAC passages for blockages or heavy deposits. Repair as necessary. After repairs, go to step 13 . If passages are okay, go to next step.
10. Replace IAC valve. After repairs, go to step 13 .
11. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to next step.
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0506. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0506: IDLE SYSTEM LOW (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. If PCM detects that idle speed is out of IAC systems range of control at idle, it will perform an active test while vehicle is being driven.

During this test, PCM will command IAC valve to move while monitoring MAF. If expected change in MAF is detected, and IAC operation is verified, but since idle RPM is out of IAC system control and IAC valve is working, DTC P0506 will set. DTC P1508 will set, when there is no change in MAF, and IAC valve is functional, but idle RPM is out of IAC system control.

DTC will set when the following conditions are present

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0171, P0172, P0174, P0175, P0300, P0401, P0404, P0405, P0443, P0500, P0501, P0502, P0503 or P1441 not set.
2. Engine running greater than 60 seconds.
3. Engine coolant temperature greater than 140°F (60°C).
4. IAT greater than 14°F (-10°C).
5. BARO greater than 65 kPa.
6. Ignition voltage 9-17 volts.
7. Vehicle speed less than one MPH.
8. Actual idle speed is 100 RPM less than desired idle speed.
9. Above conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM from 500 RPM up to 1500 RPM, then 1500 RPM to 500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM does not respond as commanded, go to next step.
3. If engine RPM is too high (greater than 100 RPM), go to next step. If RPM does not change significantly, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0506. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0507: IAC SYSTEM-HIGH RPM (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which can vary depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

Conditions for setting this DTC are as follows

1. DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0123, P0125, P0131, P0132, P0133, P0134, P0200, P0300, P0301, P0302, P0303, P0304, P0335, P0341, P0342, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P0502, P0506, P0601, P0602, P0705, P0706, P1133, P1404 and P1441 not set.
2. IAC valve counts are less than 2 counts.
3. BARO is greater than 72 kPa.
4. ECT greater than 104°F (40°C).
5. Idle speed deviates less than desired RPM by greater than 60 RPM for greater than 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Ensure engine is at normal operating temperature, transmission is in Park or Neutral, parking brake is set and A/C is off. Using scan tool, command IAC valve from 900 to 2000 RPM. If engine RPM changes smoothly, go to next step. If engine RPM does not change smoothly, go to step 5 .
3. Turn ignition off. Disconnect IAC valve connector. Remove IAC valve. Measure resistance IAC windings between IAC valve terminals "A" and "B", and then terminals "C" and "D". If each reading is 40-80 ohms, go to next step. If one or both readings are not 40-80 ohms, go to step 13 .
4. Check resistance between IAC valve terminals "B" and "C", and then between terminals "A" and "D". If each reading is infinite, go to step 15 . If one or both readings are not infinite, go to step 13 .
5. Turn ignition on, with engine off. Disconnect IAC valve connector. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 of the terminals, go to next step. If test light does not illuminate on 2 the terminals, go to step 7 .
6. With test light connected to positive battery terminal, probe all 4 terminals at IAC valve harness connector. If test light illuminates on 2 of the terminals, go to step 8 . If test light does illuminate on 2 of the terminals, go to step 9 .
7. Check for an open or short to ground in IAC valve low and high circuits. Repair as necessary. After repair is completed, go to step 15 . If circuits are okay, go to step 10 .
8. Start engine and allow to idle. With test light connected to ground, probe all 4 terminals at IAC valve harness connector. If test light flashes on and off for all 4 terminals, go to step 11 . If test light does not flash on and off for all 4 terminals, go to step 12 .
9. Check for an open or short to voltage in IAC valve low and high circuits. Repair as necessary. After repair is completed, go to step 15 . If circuits are okay, go to next step.
10. Check PCM harness connector terminals for poor connections. Repair as necessary. After repairs, go to step 15 . If connector is okay, go to step 14 .
11. Inspect IAC valve passages. Repair as necessary. After repairs, go to step 15 . If IAC passages are okay, go to step 13 .
12. If test light remained on constantly for terminals that did not flash in step 8 , go to step 9 . If test light did not remain on constantly for terminals that did not flash, go to step 7 .
13. Replace IAC valve. After replacing IAC valve, go to step 15 .
14. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
15. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter DTC P0507. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
16. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

Inspect IAC valve connector for proper connection. Check for damaged wiring harness. Check for disconnected, cracked or split vacuum hoses. Check PCV valve for proper installation. Inspect intake manifold for cracks.

DTC P0507: IDLE SPEED HIGH (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

IAC system controls idle speed by allowing a controlled amount of air to by-pass throttle blade via a passage in IAC valve. ECM controls IAC system to maintain a desired idle speed. Speed may vary depending on input to ECM and other criteria. If ECM detects engine speed is outside IAC system's range of control at idle, this DTC will set.

Conditions required to set DTC are

1. Actual engine RPM is greater than desired idle speed by at least 200 RPM.
2. Short term air trim is lower than -1.66 gm/s.
3. Fuel cutoff occurs greater than 3 times when diagnostic is performed.
4. Conditions are met for greater than 8 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Load engine by turning on several accessories (A/C, headlights, rear defogger, etc.). If actual engine speed is not greater than 200 RPM or less than 100 RPM of desired idle speed, fault is not present. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If actual engine speed is greater than 200 RPM or not less than 100 RPM of desired idle speed, go to next step.
3. If engine RPM is too high, go to next step. If engine RPM is not too high, go to step 5 .
4. Check for vacuum leaks, throttle blade not closing properly, faulty PCV system or mechanical IAC valve failure. Repair component as necessary. After repairs, go to step 6 .
5. Check for excessive deposits in throttle body or IAC valve passages. Check for kinked or obstructed IAC air supply hose. Inspect for IAC valve mechanical failure. Check for parasitic load on engine (transmission problem, belt driven accessory problem, etc.). Check for mechanical engine problem. Repair as necessary. After repairs, go to next step.
6. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0507 is set, go to step 2 . If DTC P0507 is not set, go to next step.
7. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

For any test that requires probing ECM or component harness connectors, use Connector Test Adapter Kit (J-35616-A). This will prevent damage to harness connector terminals. Check for the following conditions

Check for poor connections at ECM or at component. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection.

Check for damaged wiring harness. If harness appears to be okay, observe scan tool while moving related connectors and wiring harnesses. A change in scan tool display may help to locate fault.

DTC P0507: IDLE CONTROL SYSTEM-HIGH RPM (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The Idle Air Control (IAC) valve is controlled by the Powertrain Control Module (PCM). PCM uses the IAC to maintain a desired idle speed, which varies depending on input to PCM. Scan tool reads IAC valve pintle position in counts. The higher the counts, the more air that is allowed to by-pass the throttle plate.

Conditions for setting this DTC are as follows

1. No VSS, TP sensor, EVAP system, EVAP solenoid, misfire, IAT sensor, MAP sensor, fuel trim, fuel injector, EGR pintle position, ECT sensor, CKP sensor, or MAF sensor related DTCs set.
2. BARO greater than 65 kPa.
3. System voltage 9-16 volts.
4. ECT greater than 122°F (70°C).
5. Engine running for at least 125 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, go to next step.
3. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring engine speed display. If engine speed remains within 50 RPM of desired RPM for each RPM command, no problem is detected at this time. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If engine speed does not remain within 50 RPM of desired RPM for each RPM command, go to next step.
4. Disconnect IAC valve harness connector. Install IAC Noid Light (J-37027-A) to IAC valve harness connector. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring engine speed display. If each noid light cycles Red and Green but never off, go to step 6 . If each noid light does not cycle Red and Green, go to next step.
5. Check for an open, short to voltage or short to ground in IAC valve related circuits between IAC valve and PCM. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Check for vacuum leaks. Check for binding throttle plate or throttle shaft. Check for misadjusted throttle and cruise control cables. Check PCV system operation. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for poor connection at IAC valve connector. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 . If no problem is found, go to next step.
9. Check for poor connection at PCM valve connector. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Ensure all accessories are off. Using scan tool, command RPM up to 1500, down to 650 and then up to 1500 while monitoring ENGINE SPEED display. If engine speed remains within 50 RPM of desired RPM for each RPM command, repair is complete. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If engine speed does not remain within 50 RPM of desired RPM for each RPM command, repeat step 2 .

Inspect IAC valve connector for proper connection. Inspect throttle linkage for signs of binding or excessive wear. A slow or unstable idle may be caused by one of the following

1. Fuel system too rich or too lean.
2. Foreign material in throttle body bore or in air induction system.
3. Leaking or restricted intake manifold.
4. Excessive engine overloading.
5. Too high a viscosity engine oil.

Reviewing FAILURE RECORDS vehicle mileage since diagnostic test last failed may help determine how often condition that caused DTC to be set occurs.

DTC P0507: IDLE CONTROL SYSTEM-HIGH RPM (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM. PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

DTC will set when engine speed is over 100 RPM less than desired idle. DTC will also set when, there is no fuel injector faults, misfire, fuel trim, CKP, ECT, EVAP, EGR, VSS, TP, IAT, MAP or MAF sensor DTCs set, BARO is greater than 65 kPa, engine running for at least 3 minutes, system voltage 9-18 volts, ECT greater than 158°F (70°F), vehicle speed is less than 3 MPH, IAT is greater than 0°F (-18°C) or when throttle is closed.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If ENGINE SPEED is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027-A) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 650 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not off as RPM changes from 650-1500 RPM. If lights flash as specified, go to step 6 . If lights are not flashing as specified, go to next step.
5. Check IAC "A" high and low, and IAC "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 100 RPM of desired RPM for each command, go to next step. If ENGINE SPEED is not as specified, return to step 2 .
12. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, go to applicable DTC test. If no other DTCs are present, system is okay.

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. Check for large vacuum leak, such as incorrectly installed PCV valve or disconnected brake booster hose. Check for restricted air intake system.

DTC P0507: IAC SYSTEM-HIGH RPM (3.8L "C", "F", "G", "H" & "W" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. PCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

PCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

Conditions required to set DTC are

1. No CKP, ECT, IAT, MAF, MAP, TP or VSS sensor DTCs set.
2. No EVAP solenoid, EVAP system, fuel trim, fuel injector, EGR flow or EGR pintle position DTCs set.
3. ECT greater than 158°F (70°C).
4. Engine running at least 5 seconds.
5. BARO greater than 65 kPa.
6. Vehicle speed less than 3 MPH.
7. IAT greater than -4°F (-20°C).
8. Throttle closed.
9. Engine speed greater than 175 RPM, higher than desired idle.
10. Conditions met for longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs before proceeding. If no other DTCs are set, go to next step.
3. Start engine. Turn all accessories off. Using scan tool, monitor engine speed and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If engine speed remains within 100 RPM of desired RPM for each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If engine speed is not as specified, to next step.
4. Disconnect IAC harness connector. Install IAC Noid Light (J-37027) in IAC harness connector. Monitor noid lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. Both noid lights should cycle Green and Red, but not OFF as RPM changes from 500-1500 RPM. If lights flash as specified, go to step 6 . If noid lights do not flash as specified, go to next step.
5. Check IAC "A" high and low, and "B" high and low circuits for open, short to voltage or short to ground. Repair as necessary. After repairs, go to step 11 . If circuits are okay, go to step 9 .
6. Check for vacuum leaks. Ensure throttle stop screw has not been tampered with. Check for throttle plate or shaft binding. Check accelerator and speed control cables for misadjustment or binding. Check for faulty, missing or incorrectly installed PCV valve. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
7. Check for faulty connection at IAC harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
8. Replace IAC valve. After replacing IAC valve, go to step 11 .
9. Check for faulty connection at PCM harness connector. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
11. Start engine. Turn all accessories off. Using scan tool, monitor engine speed and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If engine speed remains within 100 RPM of desired RPM for each command, repair is complete. If engine speed is not as specified, return to step 2 .

Check for faulty connection at IAC and PCM connectors. Check for damaged harness. Check for vacuum leaks. Check throttle body bore and IAC for excessive deposits. Check throttle plate for sticking.

DTC P0507: IAC SYSTEM-HIGH RPM (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This test determines if idle control system is maintaining the proper idle speed. The IAC system controls idle speed by allowing a certain amount of air to by-pass the throttle body (throttle plate closed during idle) through the IAC valve. The PCM controlled IAC motor moves a pintle in and out of IAC valve, varying the amount of air entering the intake manifold. DTC will set when engine idle speed is greater than the desired idle speed for 15 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, check if other DTCs are present. If other DTCs are present, diagnose affected DTCs first. If other DTCs are not present, go to next step.
3. Start and idle engine. Turn off all accessories. Using scan tool, select MISC TESTS and select IAC SYSTEM. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring ENGINE SPEED display. If ENGINE SPEED display remains within 50 RPM of desired value for each RPM command, fault is not present. If engine speed is not within 50 RPM of desired value, go to next step.
4. Disconnect IAC valve. Install IAC Noid Light (J-37027). Start engine. Command engine speed up to 1500 RPM, down to 500 RPM, then back to 1500 RPM while monitoring noid light. If noid light cycles Red and Green (never off), go to step 6 . If noid light does not cycle, go to next step.
5. Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 9 .
6. Check throttle body for objects blocking IAC passage or throttle bore, excessive deposits in IAC passage, pintle, throttle bore or throttle plate. Check for restriction or vacuum leaks in air intake system. Check adjustment screw for tampering. Repair as necessary. If no problems are found, go to next step.
7. Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
8. Replace IAC valve.
9. Check IAC terminal contacts at PCM harness connector C1. Repair as necessary. If terminal contacts are okay, go to next step.
10. Replace PCM. Program replacement PCM using required equipment.

DTC P0507: IDLE CONTROL SYSTEM-HIGH RPM (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM controls idle speed with an Idle Air Control (IAC) valve to a calculated desired RPM based on sensor inputs and actual engine RPM. VCM uses 4 circuits to move an IAC valve, allowing varying amounts of airflow into intake manifold.

To increase idle RPM, VCM moves IAC valve out, allowing more air to by-pass throttle plate. To decrease RPM, VCM moves IAC valve in, reducing amount of air by-passing throttle plate. Scan tool reads VCM commands to IAC valve in counts. The higher the counts, the more air that is allowed to by-pass throttle plate (higher idle). The lower the counts, less air is allowed to by-pass throttle plates (lower idle).

Conditions for setting DTC

1. No ECT, MAP, TP or VS sensor DTCs are set.
2. ECT greater than 122°F (50°C).
3. IAT greater than -13°F (-25°C).
4. BARO greater than 70 kPa (10,300 ft.).
5. Vehicle speed less than 2 MPH.
6. System voltage 10-16 volts.
7. Engine run time greater than 30 seconds.
8. TP less than one percent.
9. Conditions are met for greater than 3 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Install scan tool. Check if any other DTCs are set. If other DTCs are not set, go to next step. If other DTCs are set, go to that DTC test.
3. Check if DTC P0507 is active this ignition cycle. If DTC P0507 is active this ignition cycle, go to step 5 . If DTC P0507 is not active this ignition cycle, go to next step.
4. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Problem is engine mechanical related. Repair as necessary. After repairs, go to step 7 .
6. Using scan tool, clear codes. Start engine. Idle at operating temperature. Select SPECIFIC DTC for this DTC. Operate vehicle under conditions which originally set DTC. If scan tool indicates DTC test has run and passed, go to next step. If scan tool does not indicate that this DTC test has ran and passed, go to step 2 .
7. Using scan tool, select CAPTURE INFO function. Review stored info. If other DTCs are stored, go to applicable DTC. If no other DTCs are set, system is okay.

DTC could be caused by an IAC valve which is stopped and cannot respond to VCM, a throttle stop screw which has been tampered with, or a damaged throttle or linkage.

A slow, unstable or fast idle could be caused by a non-IAC valve system problem that cannot be overcome by IAC valve. See appropriate TROUBLE SHOOTING - NO CODES article. Out of range control IAC scan tool counts will be greater than 60 if idle is too low, and zero if idle is too high. Check for fuel system too lean and rich. Check throttle body bore for foreign material. IAC reset is done with scan tool miscellaneous functions mode.

DTC P0507: IDLE CONTROL SYSTEM-HIGH RPM (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM controls idle speed with an Idle Air Control (IAC) valve to a calculated RPM based on sensor inputs and actual engine RPM. VCM moves IAC valve in or out to vary amount of airflow into intake manifold and thus decrease or increase idle RPM.

VCM commands IAC in counts. A higher count, allows more air to by-pass throttle plate (higher idle).

Conditions for setting DTC

1. No ECT, MAP, TP or VS sensor DTCs set.
2. ECT greater than 122°F (50°C).
3. IAT greater than -13°F (-25°C).
4. BARO greater than 70 kPa.
5. Vehicle speed less than 2 MPH.
6. System voltage between 10-16 volts.
7. TP less than one percent.
8. Engine running longer than 30 seconds.
9. Conditions met for greater than 3 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read DTCs. If any other DTCs are set, diagnose affected DTCs. If no other DTCs are set, go to next step.
3. If DTC P0507 is active this ignition cycle, go to step 6 . If DTC is not active this ignition cycle, go to next step.
4. DTC is intermittent. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Repair engine mechanical problem. After repairs, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool indicates that this test RAN AND PASSED, go to next step. If scan tool does not indicate that this test RAN AND PASSED, repeat step 2 .
7. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Reset IAC using scan tool MISC FUNCTIONS. Check if fuel system is running too rich or too lean. Inspect throttle body bore for foreign material.

DTC P0507: IDLE SPEED HIGH (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. If PCM detects that idle speed is out of IAC systems range of control at idle, it will perform an active test while vehicle is being driven.

DTC will set when actual idle speed is 200 RPM greater than desired speed for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM from 500 RPM up to 1500 RPM, then from 1500 RPM to 500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM did not respond to within 100 RPM of each command, go to next step.
3. If engine RPM is greater than 100 RPM of desired RPM, go to next step. If RPM is not greater than 100 RPM of desired RPM, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 13 . If no problems were found, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to step 13 . If no problems were found, go to next step.
6. Turn ignition off. Disconnect IAC harness connector and install IAC Noid Light (J-37027-A). Start and operate engine at idle. Using scan tool, command RPM up to 1500 RPM, down to 500 RPM and up to 1500 RPM. Observe noid light. If both LEDs on noid light cycle Red and Green, but never off, go to next step. If both LEDs on noid light does not cycle Red and Green, go to step 8 .
7. Turn ignition off. Remove IAC valve. Connect IAC valve to IAC Driver Tool (J-37027-A). Hold IAC valve pintle with finger to prevent pintle from dropping. Using IAC driver, retract and extent pintle. If pintle moves steadily with each flash of the IAC driver light, go to step 9 . If pintle does not move steadily with each flash of the IAC driver light, go to step 10 .
8. Check IAC circuit for poor connections, open circuit, or short to ground or voltage. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to step 11 .
9. Inspect IAC passages for blockage or heavy deposits. Clean passages as necessary. After cleaning passages, go to step 13 .
10. Replace IAC valve. After replacing IAC valve, go to step 13 .
11. Check for poor connections at PCM terminals. Repair as necessary. After repairs, go to step 13 . If terminal connections are okay, go to next step.
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0507: IDLE SPEED HIGH (5.7L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. DTC P0507 will set if PCM detects that idle speed is out of IAC systems range of control at idle.

DTC will set when the following conditions are present

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0171, P0172, P0174, P0175, P0200, P0300, P0401, P0404, P0405, P0443, P0500-P0503 or P1441 are not set.
2. Engine running for more than 60 seconds.
3. Engine coolant temperature is greater than 140°F (60°C).
4. IAT greater than 14°F (-10°C).
5. BARO greater than 65 kPa.
6. Ignition voltage 9-18 volts.
7. Vehicle speed less than one MPH.
8. Actual idle speed is 200 RPM greater than desired idle speed.
9. Above conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM up to 1500 RPM, down to 500 RPM, and then up to 1500 RPM. Exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM does not respond as commanded, go to next step.
3. If engine speed is more than 100 RPM greater than desired RPM, go to next step. If engine speed is not as specified, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to step 11 . If no problem is found, go to next step.
6. Turn ignition off. Disconnect IAC harness connector. Install appropriate IAC test light (included in Kit J-37027-A). Start engine and allow it to idle. Using scan tool, command RPM up to 1500 RPM, down to 500 RPM, and then up to 1500 RPM while observing test light. If both LEDs cycle Red and Green, but never OFF, go to next step. If test light does not react as specified, go to step 8 .
7. Turn ignition off. Remove IAC valve. Connect IAC valve to IAC driver tool (included in Kit J-37027-A). Hold IAC valve with a finger over pintle to prevent overextension. Using driver tool, retract and extend pintle. If pintle moves steadily with each flash of test light, go to step 9 . If operation is not as specified, go to step 10 .
8. Check IAC harness for faulty connections, shorts to battery voltage or ground, or opens. Repair as necessary. After repairs, go to step 13 . If harness is okay, go to step 11 .
9. Check IAC passages for blockages or heavy deposits. Repair as necessary. After repairs, go to step 13 . If passages are okay, go to next step.
10. Replace IAC valve. After repairs, go to step 13 .
11. Check for faulty PCM connections. Repair as necessary. After repairs, go to step 13 . If connections are okay, go to next step.
12. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
13. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0507. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
14. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0507: IDLE SPEED HIGH (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Idle Air Control (IAC) valve is controlled by PCM. PCM uses IAC to maintain a desired idle speed, which can vary depending on input to PCM and other criteria. If PCM detects that idle speed is out of IAC systems range of control at idle, it will perform an active test while vehicle is being driven.

DTC will set when the following conditions are present

1. DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0125, P0171, P0172, P0174, P0175, P0300, P0401, P0404, P0405, P0441, P0443, P0500, P0501, P0502, P0503, P1120, P1220, P1221 or P1441 not set.
2. Engine running greater than 60 seconds.
3. Engine coolant temperature greater than 140°F (60°C).
4. IAT greater than 14°F (-10°C).
5. BARO greater than 65 kPa.
6. Ignition voltage between 9-17 volts.
7. Vehicle speed not greater than one MPH.
8. APP indicated angle zero percent on "Y" Body.
9. Actual idle speed is 200 RPM greater than desired idle speed.
10. Conditions present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, command RPM from about 500 to 1500 RPM. Repeat 2 times and exit from test. If RPM change responded to within 100 RPM of each command, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If RPM does not respond as commanded, go to next step.
3. If engine RPM is too high (greater than 100 RPM), go to next step. If RPM does not change significantly, go to step 5 .
4. Check for vacuum leaks, throttle plates not closing properly or for faulty PCV valve. Repair as necessary. After repairs, go to step 6 .
5. Check for excessive deposits in throttle body. Check for parasitic load on engine (i.e., transmission problem). Repair as necessary. After repairs, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0507. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0522: ENGINE OIL PRESSURE SENSOR CIRCUIT-LOW VOLTAGE (3.8L "C" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Engine oil pressure sensor sends oil pressure information to PCM. The PCM transmits this information to Instrument Panel Cluster (IPC) via serial data circuit.

Engine oil pressure is displayed on scan tool in volts. A low voltage reading indicates low oil pressure. As oil pressure increases, voltage will increase. Normal range for engine oil pressure sensor signal voltage is 0.5 volt at zero psi (0 kg/cm 2 ) to 4.5 volts at 128 (9 kg/cm 2 ).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor Engine Oil Pressure (EOP) sensor. If voltage is less than 0.4 volt, go to step 5 . If voltage is not less than 0.4 volt, go to next step.
3. If voltage is greater than 4 volts, go to next step. If voltage is not greater than 4 volts, go to step 19 .
4. While monitoring EOP sensor, disconnect EOP sensor harness connector. If voltage is zero volts, go to step 12 . If voltage is not zero volts, go to step 11 .
5. Disconnect EOP sensor harness connector. Connect a fused jumper wire between signal circuit and 5-volt reference "A" circuit at EOP sensor harness connector. Monitor EOP sensor with scan tool. If voltage is near 5 volts, go to step 16 . If voltage is not near 5 volts, go to next step.
6. Measure voltage between 5-volt reference "A" circuit and ground circuit at EOP sensor harness connector. If voltage is near 5 volts, go to step 9 . If voltage is not near 5 volts, go to next step.
7. Check 5-volt reference "A" circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
8. Check for an open in 5-volt reference "A" circuit. If a problem is found, go to step 18 . If circuit is okay, go to step 13 .
9. Check EOP sensor signal circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
10. Check EOP sensor signal circuit between EOP sensor harness connector and PCM for an open or short to ground. If a problem is found, go to step 18 . If circuit is okay, go to step 22 .
11. Check EOP sensor signal circuit between EOP sensor harness connector and PCM for short to voltage. If a problem is found, go to step 18 . If circuit is okay, go to step 22 .
12. Check 5-volt reference "A" circuit for short to voltage. If a problem is found, go to step 18 . If circuit is okay, go to next step.
13. Check EOP sensor ground circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
14. Check EOP sensor ground circuit for faulty connection at EOP sensor harness connector. If a problem is found, go to step 17 . If connection is okay, go to next step.
15. Check for an open in EOP sensor ground circuit. If a problem is found, go to step 18 . If circuit is okay, go to step 21 .
16. Check 5-volt reference "A" circuit and EOP sensor signal circuit for faulty connection at EOP sensor. If a problem is found, go to next step. If connections are okay, go to step 21 .
17. Repair faulty harness connector terminal. After repairs, go to step 23 .
18. Repair open or shorted circuit in wiring harness. After repairs, go to step 23 .
19. Turn ignition off. Remove EOP sensor. Install oil pressure gauge. Operate vehicle under same conditions as when incorrect oil pressure condition was noticed. If measured oil pressure is near oil pressure reading on instrument panel, diagnose engine mechanical problem. If measured oil pressure is not near oil pressure reading on instrument panel, go to next step.
20. Check circuits related to EOP sensor for high resistance and faulty connections at EOP sensor or PCM. Repair as necessary. After repairs, go to step 23 . If circuits and connections are okay, go to next step.
21. Replace EOP sensor. After repairs, go to step 23 .
22. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
23. Turn ignition on, with engine off. Using scan tool, monitor EOP sensor. If voltage is near 0.4 volt, go to next step. If voltage is not near 0.4 volt, go to step 2 .
24. Start engine and increase engine speed to 2500 RPM. Using scan tool, monitor EOP sensor. If voltage is greater than 4.4 volts, go to step 2 . If voltage is not greater than 4.4 volt, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

If problem with engine oil pressure cannot be isolated, check instrument cluster by performing appropriate system test. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

DTC P0522: ENGINE OIL PRESSURE SENSOR CIRCUIT-LOW VOLTAGE (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Test Description

Engine oil pressure sensor is mounted on top rear of engine. Sensor measures changes in engine oil pressure. Sensor has a 5-volt reference, ground and signal circuit. Sensor changes resistance based on engine oil pressure. When PCM senses a signal voltage lower than the normal operating range of the sensor (.48 volt), DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC STATUS for DTC P1635. If scan tool indicates that DTC P1635 failed in this ignition cycle, diagnose DTC P1635 first. If scan tool does not indicate that DTC P1635 failed this ignition cycle, go to next step.
3. Using scan tool, monitor engine oil pressure voltage at idle. If voltage reading is less than 0.48 volt, go to step 5 . If voltage reading is not less than 0.48 volt, go to next step.
4. Turn ignition on, with engine off. Review FREEZE FRAME data and note parameters. Operate vehicle within FREEZE FRAME parameters. If test indicates that this test failed this ignition cycle while operating vehicle, go to next step. If test does not indicate that this test failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect engine oil pressure sensor harness connector. Jumper sensor 5-volt reference circuit and signal circuit at harness connector. Observe engine oil pressure voltage on scan tool. If voltage reading is about 5 volts, go to step 11 . If voltage reading is not about 5 volts, go to next step.
6. Connect test light between battery voltage and sensor signal circuit at harness connector. Observe sensor voltage on scan tool. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step 9 .
7. Turn ignition off. Disconnect PCM harness connector. Check oil pressure sensor 5-volt reference circuit for open or short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
8. Check 5-volt reference circuit at PCM connector for poor connection. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
9. Turn ignition off. Disconnect PCM harness connector. Check oil pressure sensor signal circuit for open, or short to ground. Repair as necessary. After repairs, go to step 13 . If circuit is okay, go to next step.
10. Check engine oil pressure sensor signal circuit for poor connection at PCM. Repair as necessary. After repairs, go to step 13 . If connection is okay, go to step 12 .
11. Perform engine oil pressure check. Repair as necessary. If oil pressure is okay, replace engine oil pressure sensor. After replacing sensor, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
13. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter DTC P0507. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2 .
14. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for misrouted harness, rubbed through wire insulation or broken wire inside insulation. Ensure connectors are tight and clean.

DTC P0523: ENGINE OIL PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (3.8L "C" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Engine oil pressure sensor sends oil pressure information to PCM. The PCM transmits this information to Instrument Panel Cluster (IPC) via serial data circuit.

Engine oil pressure is displayed on scan tool in volts. A low voltage reading indicates low oil pressure. As oil pressure increases, voltage will increase. Normal range for engine oil pressure sensor signal voltage is 0.5 volt at zero psi (0 kg/cm 2 ) to 4.5 volts at 128 (9 kg/cm 2 ).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, monitor Engine Oil Pressure (EOP) sensor. If voltage is less than 0.4 volt, go to step 5 . If voltage is not less than 0.4 volt, go to next step.
3. If voltage is greater than 4 volts, go to next step. If voltage is not greater than 4 volts, go to step 19 .
4. While monitoring EOP sensor, disconnect EOP sensor harness connector. If voltage is zero volts, go to step 12 . If voltage is not zero volts, go to step 11 .
5. Disconnect EOP sensor harness connector. Connect a fused jumper wire between signal circuit and 5-volt reference "A" circuit at EOP sensor harness connector. Monitor EOP sensor with scan tool. If voltage is near 5 volts, go to step 16 . If voltage is not near 5 volts, go to next step.
6. Measure voltage between 5-volt reference "A" circuit and ground circuit at EOP sensor harness connector. If voltage is near 5 volts, go to step 9 . If voltage is not near 5 volts, go to next step.
7. Check 5-volt reference "A" circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
8. Check for an open in 5-volt reference "A" circuit. If a problem is found, go to step 18 . If circuit is okay, go to step 13 .
9. Check EOP sensor signal circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
10. Check EOP sensor signal circuit between EOP sensor harness connector and PCM for an open or short to ground. If a problem is found, go to step 18 . If circuit is okay, go to step 22 .
11. Check EOP sensor signal circuit between EOP sensor harness connector and PCM for short to voltage. If a problem is found, go to step 18 . If circuit is okay, go to step 22 .
12. Check 5-volt reference "A" circuit for short to voltage. If a problem is found, go to step 18 . If circuit is okay, go to next step.
13. Check EOP sensor ground circuit for faulty connection at PCM. If a problem is found, go to step 17 . If connection is okay, go to next step.
14. Check EOP sensor ground circuit for faulty connection at EOP sensor harness connector. If a problem is found, go to step 17 . If connection is okay, go to next step.
15. Check for an open in EOP sensor ground circuit. If a problem is found, go to step 18 . If circuit is okay, go to step 21 .
16. Check 5-volt reference "A" circuit and EOP sensor signal circuit for faulty connection at EOP sensor. If a problem is found, go to next step. If connections are okay, go to step 21 .
17. Repair faulty harness connector terminal. After repairs, go to step 23 .
18. Repair open or shorted circuit in wiring harness. After repairs, go to step 23 .
19. Turn ignition off. Remove EOP sensor. Install oil pressure gauge. Operate vehicle under same conditions as when incorrect oil pressure condition was noticed. If measured oil pressure is near oil pressure reading on instrument panel, diagnose engine mechanical problem. If measured oil pressure is not near oil pressure reading on instrument panel, go to next step.
20. Check circuits related to EOP sensor for high resistance and faulty connections at EOP sensor or PCM. Repair as necessary. After repairs, go to step 23 . If circuits and connections are okay, go to next step.
21. Replace EOP sensor. After repairs, go to step 23 .
22. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
23. Turn ignition on, with engine off. Using scan tool, monitor EOP sensor. If voltage is near 0.5 volt, go to next step. If voltage is not near 0.5 volt, go to 2 .
24. Start engine and increase engine speed to 2500 RPM. Using scan tool, monitor EOP sensor. If voltage is greater than 4.4 volts, go to step 2 . If voltage is not greater than 4.4 volt, system is okay.

Intermittent can be caused by poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check connectors for backed-out terminals, improper mating, broken lock, damaged terminal or poor terminal to wire connection.

If problem with engine oil pressure cannot be isolated, check instrument cluster by performing appropriate system test. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

DTC P0523: ENGINE OIL PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Engine oil pressure sensor is mounted on top rear of engine. Sensor measures changes in engine oil pressure. Sensor has a 5-volt reference, ground and signal circuit. Sensor changes resistance based on engine oil pressure. When PCM senses a signal voltage high than the normal operating range of the sensor (4.5 volts), DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC STATUS for DTC P1635. If scan tool indicates that DTC P1635 failed in this ignition cycle, diagnose DTC P1635 first. If scan tool does not indicate that DTC P1635 failed this ignition cycle, go to next step.
3. Using scan tool, monitor engine oil pressure voltage at idle. If voltage reading is greater than 4.5 volts, go to step 5 . If voltage reading is not greater than 4.5 volts, go to next step.
4. Turn ignition on, with engine off. Review FREEZE FRAME data and note parameters. Operate vehicle within FREEZE FRAME parameters. If test indicates that this test failed this ignition cycle while operating vehicle, go to next step. If test does not indicate that this test failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect engine oil pressure sensor harness connector. Observe engine oil pressure voltage on scan tool. If voltage reading is less than one volt, go to next step. If voltage reading is not less than one volt, go to step 7 .
6. Connect test light between battery voltage and sensor ground circuit at harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to step 9 .
7. Check engine oil pressure sensor signal circuit for short to voltage or short to 5-volt reference circuit. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to step 11 .
8. Check voltage between ground and 5-volt reference circuit. If voltage reading is greater than 5 volts, go to step 13 . If voltage reading is not greater than 5 volts, go to next step.
9. Check for poor sensor ground connection to PCM connector. Repair as necessary. After repairs, go to step 14 . If connection is okay, go to next step.
10. Check continuity of engine oil pressure sensor ground circuit. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 14 .
12. Perform engine oil pressure check. Repair as necessary. If oil pressure is okay, replace engine oil pressure sensor. After replacing sensor or if sensor is okay, go to step 14 .
13. Repair 5-volt reference circuit for short to voltage. After repairs, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start engine and allow it to reach operating temperature. Using scan tool, select DTC, SPECIFIC function and enter this DTC. Operate vehicle within conditions required to set DTC. If scan tool displays RAN AND PASSED, go to next step. If scan tool does not display RAN AND PASSED, return to step 2 .
15. Using scan tool, select Read and Record INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs. If no DTCs are displayed, system is okay.

Check for misrouted harness, rubbed through wire insulation or broken wire inside insulation. Ensure connectors are tight and clean.

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (2.2L "J" BODY & "S" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A/C refrigerant pressure sensor responds to changes in A/C refrigerant high side pressure. Powertrain Control Module (PCM) supplies and monitors 5-volt reference circuit to the pressure sensor. Pressure sensor operating range is 0-450 psi. At zero psi, signal voltage should be about 0.1 volt. At 450 psi or greater, signal voltage should be about 4.9 volts.

Conditions for setting this DTC are as follows

1. A/C pressure sensor signal is greater than 453 psi (4.94 volts) with A/C on.
2. A/C pressure sensor signal is greater than 363 psi (4.0 volts) with A/C off.
3. Refrigerant pressure is less than zero psi (0.20 volt), IAT signal is greater than 32°F (0°C) and DTC P0112 or P0113 is not set.
4. Refrigerant pressure is less than zero psi (0.10 volt), IAT signal is greater than 32°F (0°C) and DTC P0112 or P0113 is set.
5. Conditions exist for greater than 15 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, check for MAP or TP sensor DTCs. If DTCs are present, go to appropriate DTC for diagnosis. If DTCs are not present, go to next step.
3. Scan A/C high side value. If high side value is less than 363 psi (4.0 volts), go to next step. If high side value is not less than 363 psi (4.0 volts), go to step 5 .
4. Unplug A/C pressure sensor connector. If high side value is now less than 76 psi (1.0 volt), go to step 6 . If high side value is not less than 76 psi (1.0 volt), go to step 11 .
5. If A/C high side value is less than zero psi (0.20 volt), go to step 7 . If high side value is not less than zero psi (0.20 volt), go to step 8 .
6. Connect positive DVOM lead to battery voltage. Probe A/C pressure sensor ground circuit with negative DVOM lead. If battery voltage is present, go to step 9 . If battery voltage is not present, go to step 10 .
7. Unplug A/C pressure sensor connector. Using DVOM connected to ground, probe A/C pressure sensor harness 5-volt reference circuit. If DVOM reads about 5 volts, go to step 12 . If DVOM does not read about 5 volts, go to step 13 .
8. Start engine. Turn A/C switch to OFF position. If A/C clutch remains engaged, go to step 14 . If A/C clutch does not remain engaged, go to step 25 .
9. Replace A/C pressure sensor. After replacing sensor, go to step 25 .
10. Repair open or poor connection in pressure sensor ground circuit. After repairs, go to step 25 .
11. If voltage displayed on scan tool with pressure sensor connector unplugged is greater than 4-6 volts, go to step 16 . If voltage displayed is not greater than specification, go to step 17 .
12. Jumper A/C pressure sensor harness connector 5-volt reference circuit to refrigerant pressure signal circuit. If scan tool pressure sensor high side parameter now displays greater than 421 psi (4.6 volts), go to step 9 . If parameter does not display greater than 421 psi (4.6 volts), go to step 18 .
13. Repair open or poor connection in pressure sensor 5-volt reference circuit. After repairs, go to step 25 .
14. Unplug A/C relay. Using a test light connected to battery voltage, probe A/C relay harness control (driver) circuit terminal. If test light illuminates, go to step 19 . If test light does not illuminate, go to step 20 .
15. Replace PCM. Prior to replacement, check PCM terminals, connectors and wiring harness for damage. After replacing PCM, go to step 25 .
16. Check for short to voltage on pressure sensor signal circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 15 .
17. Check pressure sensor signal circuit for short to 5-volt reference. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 15 .
18. Connect DVOM positive lead to battery voltage and probe A/C pressure sensor signal circuit at pressure sensor connector with negative lead. If DVOM reads greater than 0.5 volt, go to step 21 . If DVOM does not read greater than 0.5 volt, go to step 22 .
19. Check A/C clutch relay control circuit for a short to ground between PCM and relay connector. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 15 .
20. If A/C clutch disengages when relay is removed, go to step 23 . If A/C clutch does not disengage when relay is removed, go to step 24 .
21. Check for short to ground or short to sensor ground in A/C pressure sensor signal circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 15 .
22. Check for open in pressure sensor signal circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 15 .
23. Replace A/C compressor relay. After replacing compressor relay, go to step 25 .
24. Repair short to battery voltage in A/C compressor clutch ignition feed circuit or faulty A/C compressor clutch. After repairs, go to next step.
25. Clear DTCs. Start engine and warm to normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates this DTC has ran and passed, go to next step. If scan tool does not indicate that this DTC ran and passed, repeat step 2 .
26. Check for additional DTCs. If additional DTCs are set, service as necessary. If no additional DTCs are set, system is okay. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

Using FREEZE FRAME data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in the FREEZE FRAME data can be useful in determining how many miles since the DTC set. The FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles the diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A/C refrigerant pressure sensor responds to changes in A/C refrigerant high side pressure. Powertrain Control Module (PCM) supplies and monitors 5-volt reference circuit to the pressure sensor. Pressure sensor operating range is 0-459 psi. At zero psi, signal voltage should be about 0.1 volt. At 459 psi or greater, signal voltage should be about 4.9 volts.

Conditions for setting this DTC are as follows

1. A/C pressure sensor signal is greater than 453 psi (4.94 volts) with A/C on.
2. A/C pressure sensor signal is greater than 363 psi (4.0 volts) with A/C off.
3. Refrigerant pressure is less than zero psi (0.20 volt), IAT signal is greater than 32°F (0°C) and DTC P0112 or P0113 is not set.
4. Refrigerant pressure is less than zero psi (0.10 volt), IAT signal is greater than 32°F (0°C) and DTC P0112 or P0113 is set.
5. Conditions exist for greater than 15 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, check for MAP or TP sensor DTCs. If DTCs are present, go to appropriate DTC for diagnosis. If DTCs are not present, go to next step.
3. Scan A/C high side value. If high side value is greater than 279 psi (3.0 volts), go to next step. If high side value is not greater than 279 psi (3.0 volts), go to step 10 .
4. Turn ignition off. Disconnect A/C pressure sensor connector. Connect DVOM between battery voltage and A/C refrigerant pressure sensor ground circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 6 .
5. Using DVOM, check voltage between ground and A/C refrigerant pressure sensor signal circuit. If voltage reading is greater than 0.5 volt, go to step 7 . If voltage reading is not greater than 0.5 volt, go to step 8 .
6. Check for open or poor connection in A/C refrigerant pressure sensor ground circuit. Repair as necessary. After repairs, go to step 10 . If circuit and connections are okay, go to step 9 .
7. Check for short to voltage in A/C refrigerant pressure sensor signal circuit. Repair as necessary. After repairs, go to step 10 . If circuit is okay, go to step 9 .
8. Replace A/C refrigerant pressure sensor. After replacing sensor, go to step 10 .
9. Replace PCM. Prior to replacement, check PCM terminals, connectors and wiring harness for damage. After replacing PCM, go to next step.
10. Clear DTCs. Start engine and idle to normal operating temperature. Operate vehicle within conditions which set code. If scan tool indicates this code diagnostic has ran and passed, go to next step. If scan does not indicate that test ran and passed, repeat step 2 .
11. Check if additional DTCs are set. Diagnose affected DTCs. If no additional DTCs are set, system is okay. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

Using FREEZE FRAME data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in the FREEZE FRAME data can be useful in determining how many miles since the DTC set. The FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles the diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses input signal from A/C refrigerant pressure sensor to determine if it should turn on engine coolant fans. When signal is out of range, DTC P0530 sets and PCM will not allow A/C clutch to engage.

Conditions required to set DTC are

1. Engine is running.
2. System voltage is greater than 10 volts.
3. A/C is requested.
4. A/C refrigerant pressure sensor signal less than 0.4 volt.

Or

1. A/C refrigerant pressure sensor signal greater than 4.6 volts.
2. Either condition present longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read A/C refrigerant pressure sensor voltage. If voltage reading is less than 0.1 volt, go to step 5 . If voltage reading is not less than 0.1 volt, go to next step.
3. If voltage reading is greater than 4.6 volts, go to next step. If voltage reading is not greater than 4.6 volts, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. While observing scan tool, disconnect A/C refrigerant pressure sensor connector. If voltage reading is about zero volts, go to step 12 . If voltage reading is not as specified, go to step 11 .
5. Disconnect A/C refrigerant pressure sensor connector. Connect a fused jumper wire between A/C refrigerant pressure sensor harness connector 5-volt reference and signal circuit. If voltage reading is about 5 volts, go to step 16 . If voltage reading is not as specified, go to next step.
6. Using a DVOM, check voltage between A/C pressure sensor harness connector 5-volt reference and ground circuits. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not as specified, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
8. Check for open or a faulty splice in 5-volt reference circuit. If problem is found, go to step 18 . If no problem is found, go to step 13 .
9. Check A/C refrigerant signal circuit for faulty connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
10. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for open or short to ground. If problem is found, go to step 18 . If no problem is found, go to step 20 .
11. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for short to voltage. If problem is found, go to step 18 . If no problem is found, go to step 20 .
12. Check 5-volt reference circuit for short to voltage. If problem is found, repair as necessary. After repairs, go to step 21 . If no problem is found, go to next step.
13. Check for faulty sensor ground circuit terminal connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
14. Check for faulty sensor ground circuit terminal connection at A/C refrigerant pressure sensor connector. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
15. Check for open or faulty splice in sensor ground circuit. If a problem is found, go to step 18 . If no problem is found, go to step 19 .
16. Check for faulty 5-volt reference or A/C refrigerant pressure signal circuit terminal connection at A/C refrigerant pressure sensor. If faulty connection is found, go to next step. If connections are okay, go to step 19 .
17. Replace faulty harness connector terminal. After repairs, go to step 21 .
18. Locate and repair open/short circuit in wiring harness as necessary. After repairs, go to step 21 .
19. Replace A/C refrigerant pressure sensor. After replacing sensor, go to step 21 .
20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
21. Using scan tool, clear DTCs. Read A/C refrigerant pressure sensor voltage. If voltage reading is 0.4-4.6 volts, repair is complete. If voltage reading is not as 0.4-4.6 volts, return to step 2 .

Check for faulty connections or damaged harness. Observe A/C PRESSURE display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses input signal from A/C refrigerant pressure sensor (mounted in high pressure line) to monitor A/C refrigerant pressure. PCM uses this information to turn on engine cooling fans when A/C refrigerant pressure is high and to keep compressor disengaged when refrigerant pressure is excessively high or low. PCM monitors the A/C refrigerant signal circuit and can determine when the signal is outside of the possible range of the sensor. If signal is out of range (high or low) for a prolonged period of time, PCM will set this DTC. When DTC is set, PCM will not allow compressor to engage.

DTC will set when A/C refrigerant pressure sensor signal voltage is less than 0.10 volt or when sensor signal voltage is greater than 4.9 volts and for longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, observe A/C refrigerant pressure sensor voltage. If voltage reading is less than 0.1 volt, go to step 5 . If voltage reading is not less than 0.1 volt, go to next step.
3. If voltage reading is greater than 4.6 volts, go to next step. If voltage reading is not greater than 4.6 volts, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. While observing scan tool, disconnect A/C refrigerant pressure sensor connector. If voltage reading is about zero volts, go to step 12 . If voltage reading is not as specified, go to step 11 .
5. Disconnect A/C refrigerant pressure sensor connector. Connect a fused jumper wire between A/C refrigerant pressure sensor harness connector 5-volt reference and signal circuit. If voltage reading is about 5 volts, go to step 16 . If voltage reading is not as specified, go to next step.
6. Using a DVOM, check voltage between A/C pressure sensor harness connector 5-volt reference and ground circuits. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not as specified, go to next step.
7. Check for faulty 5-volt reference "B" circuit connection at PCM connector. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
8. Check for open or short in 5-volt reference "B" circuit. If problem is found, go to step 18 . If no problem is found, go to step 13 .
9. Check A/C refrigerant signal circuit for faulty connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
10. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for open or short to ground. If problem is found, go to step 18 . If no problem is found, go to step 20 .
11. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for short to voltage. If problem is found, go to step 18 . If no problem is found, go to step 20 .
12. Check 5-volt reference circuit for short to voltage. If problem is found, repair as necessary. After repairs, go to step 21 . If no problem is found, go to next step.
13. Check for faulty sensor ground circuit terminal connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
14. Check for faulty sensor ground circuit terminal connection at A/C refrigerant pressure sensor connector. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
15. Check for open or faulty splice in sensor ground circuit. If a problem is found, go to step 18 . If no problem is found, go to step 19 .
16. Check for faulty 5-volt reference or A/C refrigerant pressure signal circuit terminal connection at A/C refrigerant pressure sensor. If faulty connection is found, go to next step. If connections are okay, go to step 19 .
17. Replace faulty harness connector terminal. After repairs, go to step 21 .
18. Locate and repair open/short circuit in wiring harness as necessary. After repairs, go to step 21 .
19. Replace A/C refrigerant pressure sensor. After replacing sensor, go to step 21 .
20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
21. Using scan tool, clear DTCs. Read A/C refrigerant pressure sensor voltage. If voltage reading is 0.1-4.8 volts, go to next step. If voltage reading is not as 0.1-4.8 volts, return to step 2 .
22. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for faulty connections or damaged harness. Observe A/C PRESSURE display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (3.8L "C", "F", "G", "H" & "W" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses input signal from A/C refrigerant pressure sensor to determine if it should turn on engine coolant fans. When signal is out of range, DTC P0530 sets and PCM will not allow A/C clutch to engage.

Conditions required to set DTC are

1. Engine running.
2. A/C is requested.
3. A/C refrigerant pressure sensor signal less than 0.1 volt.
4. A/C refrigerant pressure sensor signal greater than 4.9 volts.
5. Conditions present longer than 20 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read A/C refrigerant pressure sensor voltage. If voltage reading is less than 0.1 volt, go to step 5 . If voltage reading is not less than 0.1 volt, go to next step.
3. If voltage reading is greater than 4.8 volts, go to next step. If voltage reading is not greater than 4.8 volts, go to «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
4. While observing scan tool, disconnect A/C refrigerant pressure sensor connector. If voltage reading is about zero volts, go to step 12 . If voltage reading is not about zero volts, go to step 11 .
5. Disconnect A/C refrigerant pressure sensor connector. Connect a fused jumper wire between A/C refrigerant pressure sensor harness connector 5-volt reference and signal circuit. If voltage reading is about 5 volts, go to step 16 . If voltage reading is not about 5 volts, go to next step.
6. Using a DVOM, check voltage between A/C pressure sensor harness connector 5-volt reference and ground circuits. If voltage reading is about 5 volts, go to step 9 . If voltage reading is not about 5 volts, go to next step.
7. Check for faulty 5-volt reference circuit connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
8. Check for open or a faulty splice in 5-volt reference circuit. If problem is found, go to step 18 . If no problem is found, go to step 13 .
9. Check A/C refrigerant signal circuit for faulty connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
10. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for open or short to ground. If problem is found, go to step 18 . If no problem is found, go to step 20 .
11. Check A/C refrigerant pressure signal circuit between A/C refrigerant pressure sensor connector and PCM for short to voltage. If problem is found, go to step 18 . If no problem is found, go to step 20 .
12. Check 5-volt reference circuit for short to voltage. Repair as necessary. After repairs, go to step 18 . If no problem is found, go to next step.
13. Check for faulty sensor ground circuit terminal connection at PCM. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
14. Check for faulty sensor ground circuit terminal connection at A/C refrigerant pressure sensor connector. If faulty connection is found, go to step 17 . If connection is okay, go to next step.
15. Check for open or faulty splice in sensor ground circuit. If a problem is found, go to step 18 . If no problem is found, go to step 19 .
16. Check for faulty 5-volt reference or A/C refrigerant pressure signal circuit terminal connection at A/C refrigerant pressure sensor. If faulty connection is found, go to next step. If connections are okay, go to step 19 .
17. Replace faulty harness connector terminal. After repairs, go to step 21 .
18. Locate and repair open/short circuit in wiring harness as necessary. After repairs, go to step 21 .
19. Replace A/C refrigerant pressure sensor. After replacing sensor, go to step 21 .
20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
21. Using scan tool, clear DTCs. Read A/C refrigerant pressure sensor voltage. If voltage reading is 0.1-4.8 volts, repair is complete. If voltage reading is not 0.1-4.8 volts, return to step 2 .

Check for faulty connections or damaged harness. Observe scan tool A/C refrigerant pressure sensor display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0530: A/C REFRIGERANT PRESSURE SENSOR CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A/C refrigerant pressure sensor is located on high side of A/C system and is used to monitor refrigerant pressure. PCM uses this information to run cooling fans when A/C refrigerant pressure is high. A 5-volt reference voltage is supplied to sensor and is returned to PCM on signal circuit. Sensor resistance changes as refrigerant pressure increases or decreases.

PCM monitors A/C refrigerant pressure sensor signal circuit and can determine when A/C pressure is too high or too low. When pressures are out of range (high or low) for a predetermined time, PCM will disable A/C compressor clutch and set DTC.

DTC will set when the following conditions are present

1. A/C refrigerant pressure sensor indicates A/C refrigerant pressure is less than -8 psi for 5 seconds.
2. A/C refrigerant pressure sensor indicates A/C refrigerant pressure is greater than 448 psi for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC status for DTC P1635. If DTC P1635 failed this ignition cycle, diagnose DTC. If DTC does not fail this ignition, go to next step.
3. Turn ignition on, with engine on. Using scan tool, monitor A/C high side. If A/C high side voltage is 0.1-1.8 volts, go to next step. If A/C high side voltage is not 0.1-1.8 volts, go to step 5 .
4. Turn ignition on, with engine off. Review FREEZE FRAME data and note parameters. Operate vehicle within FREEZE FRAME parameters. If test indicates that this test failed this ignition cycle while operating vehicle, go to next step. If test does not indicate that this test failed this ignition cycle, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Disconnect A/C refrigerant pressure sensor harness connector. If scan tool indicates that A/C high side voltage is less than one volt, go to next step. If A/C high side voltage is not less than one volt, go to step 10 .
6. Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and battery ground. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 11 .
7. Using DVOM, check voltage between A/C refrigerant pressure sensor 5-volt reference circuit and sensor ground. If voltage reading is about 5 volts, go to next step. If voltage reading is not about 5 volts, go to step 12 .
8. Connect a fused jumper wire between A/C refrigerant pressure sensor 5-volt reference circuit to sensor signal ground. Scan tool should read about 5 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 13 .
9. Repair faulty A/C refrigerant pressure sensor connection or replace faulty sensor. After repairs, go to step 14 .
10. Repair short to voltage in A/C refrigerant pressure sensor signal circuit. After repairs, go to step 14 .
11. Repair 5-volt reference circuit to pressure sensor. After repairs, go to step 14 .
12. Repair ground circuit to pressure sensor. After repairs, go to step 14 .
13. Repair signal circuit to pressure sensor. After repairs, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0530. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If test failed on this ignition cycle, wiggle related electrical harness connectors while monitoring scan tool. Repair as necessary.

DTC P0532: A/C PRESSURE SENSOR CIRCUIT-LOW VOLTAGE (4.6L "K" BODY-SEVILLE)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A/C refrigerant pressure sensor changes resistance based on refrigerant pressure. PCM provides 5-volt reference and ground to sensor. Sensor signal varies between ground and 5 volts as refrigerant pressure varies/changes. As refrigerant pressure increases, voltage increases; as refrigerant pressure decreases, voltage decreases. Sensor signal will go low when a short to ground or open condition exists, setting DTC.

DTC will set when engine is running, and A/C refrigerant pressure sensor reading has been 0.10 volt or less.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, view A/C refrigerant pressure sensor value. If scan tool displays a value of 0.10 volt or less, go to next step. If scan tool does not display a value of 0.10 volt or less, fault is not present.
3. Turn ignition off. Disconnect A/C refrigerant pressure sensor. Jumper sensor harness terminals "B" and "C". Turn ignition on. If scan tool displays a value greater than 5 volts, go to step 14 . If scan tool does not display a value greater than 5 volts, go to next step.
4. Remove jumper wire. Using DVOM, check voltage between ground and sensor harness connector terminal "B". If voltage reading is 4.5 volts or greater, go to next step. If voltage reading is not 4.5 volts or greater, go to step 7 .
5. Using scan tool, record fluid life indexes. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector. Check resistance between PCM connector terminal No. 56 and ground. If resistance is less than 10,000 ohms, go to step 10 . If resistance is not less than 10,000 ohms, go to next step.
6. Check resistance between PCM connector terminal No. 56 and A/C refrigerant pressure sensor connector terminal "C". If resistance is greater than 5 ohms, go to step 11 . If resistance is not greater than 5 ohms, go to step 16 .
7. Using scan tool, view TP sensor display while slightly depressing accelerator pedal. If voltage reading is greater than 0.10 volt, go to next step. If voltage reading is not greater than 0.10 volt, go to step 9 .
8. Using scan tool, record fluid life indexes. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector. Using DVOM, check resistance between PCM connector terminal No. 67 and A/C refrigerant pressure sensor connector terminal "B". If resistance is greater than 5 ohms, go to step 12 . If resistance is not greater than 5 ohms, go to step 16 .
9. Using scan tool, record fluid life indexes. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector. Disconnect TP sensor connector. Check resistance between ground and PCM harness connector terminals No. 63 and 64. If resistance is less than 10,000 ohms, go to step 13 . If resistance is not less than 10,000 ohms, go to step 16 .
10. Repair short to ground in A/C refrigerant pressure sensor signal circuit. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
11. Repair open in A/C refrigerant pressure sensor signal circuit. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
12. Repair open in 5-volt reference circuit. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
13. Repair short to ground in circuit with low resistance. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
14. Check terminal contact at A/C refrigerant pressure sensor. Repair as necessary. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article. If terminal contact is okay, go to next step.
15. Replace A/C refrigerant pressure sensor. After replacing sensor, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
16. Check terminal contact at PCM harness connector terminals No. 46, 64 and 69. Repair as necessary. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article. If terminal contacts are okay, go to next step.
17. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, perform PCM diagnosis to verify repairs. See appropriate SYSTEM & COMPONENT TESTING article.

DTC P0533: A/C PRESSURE SENSOR CIRCUIT-HIGH VOLTAGE (4.6L "K" BODY-SEVILLE)

Note. For circuit reference, see WIRING DIAGRAMS article.

A/C refrigerant pressure sensor changes resistance based on refrigerant pressure. PCM provides 5-volt reference and ground to sensor. Sensor signal varies between ground and 5 volts as refrigerant pressure varies/changes. As refrigerant pressure increases, voltage increases; as refrigerant pressure decreases, voltage decreases. Sensor signal will go high when signal line is shorted to voltage or sensor is shorted internally, setting DTC.

DTC will set when engine is running and A/C refrigerant pressure sensor reading has been 5 volts or greater.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, check A/C refrigerant pressure sensor value. If scan tool displays a value greater than 5 volts, go to next step. If scan tool does not display a value greater than 5 volts, fault is not present.
3. Disconnect A/C refrigerant pressure sensor connector. If pressure sensor value is less than 0.10 volt, go to next step. If pressure sensor value is not less than 0.10 volt, go to step 5 .
4. Using DVOM, check voltage between ground and pressure sensor connector terminal "B". If voltage reading is greater than 5.5 volts, go to step 7 . If voltage reading is not greater than 5.5 volts, go to step 8 .
5. Using DVOM, check voltage between ground and pressure sensor connector terminal "C". If voltage reading is greater than 0.5 volt, go to next step. If voltage reading is not greater than 0.5 volt, go to step 10 .
6. Repair short to voltage in A/C refrigerant pressure sensor signal circuit. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
7. Repair short to voltage in A/C refrigerant pressure sensor 5-volt reference circuit. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
8. Check terminal contact at pressure sensor. Repair as necessary. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article. If terminal contact is okay, go to next step.
9. Replace A/C refrigerant pressure sensor. After replacing sensor, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
10. Check terminal contact at PCM harness connector terminal No. 56. Repair as necessary. After repairs, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article. If terminal contact is okay, go to next step.
11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.

DTC P0550: POWER STEERING PRESSURE SWITCH CIRCUIT (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Power Steering Pressure (PSP) switch is normally closed switch, which opens when power steering pressure exceeds 450-650 psi. The PSP switch closes again when pressure drops to less than 100-450 psi. This test monitors the PSP switch. When load is placed on power steering, such as full lock position, the switch opens. When driving at greater than 45 MPH (no load condition), the switch closes. DTC sets when vehicle speed is greater than 45 MPH and the PSP switch signal voltage is high for 60 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, select PSP SWITCH parameter. With engine running, turn steering wheel from straight ahead to full left lock position and back to straight ahead position. If scan tool displays NORMAL to HI PRESS and back to NORMAL, fault is not present. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not display NORMAL to HI PRESS and back to NORMAL, go to next step.
3. Turn engine off. Turn ignition on, with engine off. If scan tool display remains on HI PRESS, go to next step. If scan tool display does not remain on HI PRESS, check power steering system. See appropriate STEERING article in STEERING.
4. Disconnect PSP switch. Using a DVOM, check voltage between ground and PSP switch signal circuit at switch harness connector. If voltage reading is 10 volts or greater, go to next step. If voltage reading is not 10 volts or greater, go to step 6 .
5. Using a jumper wire, jumper PSP switch harness connector terminals. If scan tool displays NORMAL, go to step 9 . If scan tool does not display NORMAL, go to step 8 .
6. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector. Using DVOM, check continuity of PSP signal circuit from PCM to PSP switch harness connector. If continuity exists, go to step 10 . If continuity does not exist, go to next step.
7. Repair open or high resistance in signal circuit. After repairs, go to step 13 .
8. Repair open or high resistance in ground circuit. After repairs, go to step 13 .
9. Check for poor connections or terminals at PSP switch. Repair as necessary. After repairs, go to step 13 . If connections or terminals are okay, go to step 11 .
10. Check for poor connections or terminals at PCM. Repair as necessary. After repairs, go to step 13 . If connections or terminals are okay, go to step 12 .
11. Replace PSP switch. After replacing switch, go to step 13 .
12. Replace PCM. Program replacement PCM using required equipment.
13. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
14. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for intermittent contact at PSP switch or stretching of harness causing an intermittent open.

DTC P0550: POWER STEERING PRESSURE SWITCH CIRCUIT-LOW VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Power Steering Pressure (PSP) switch is normally closed switch, which opens when power steering pressure exceeds 450-650 psi. The PSP switch closes again when pressure drops to less than 100-450 psi. This test monitors the PSP switch. When load is placed on power steering, such as full lock position, the switch opens. When driving at greater than 45 MPH (no load condition), the switch closes. DTC sets when vehicle speed is greater than 45 MPH and the PSP switch signal is open.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, select PSP SWITCH. With engine running, turn steering wheel from straight ahead to full left lock position and back to straight ahead position. If scan tool displays NORMAL to HI PRESS and back to NORMAL, fault is not present. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not display NORMAL to HI PRESS and back to NORMAL, go to next step.
3. Turn engine off. Turn ignition on, with engine off. If scan tool display remains on HI PRESS, go to next step. If scan tool display does not remain on HI PRESS, go to step 8 .
4. Disconnect PSP switch. Using a DVOM, check voltage between ground and PSP switch harness connector terminal "B". If voltage reading is 10 volts or greater, go to next step. If voltage reading is not 10 volts or greater, go to step 10 .
5. Using jumper wire, jumper PSP switch harness connector terminals. If scan tool displays HI PRESS, go to next step. If scan tool does not display HI PRESS, go to step 11 .
6. Store fluid life value as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. With PSP switch harness connector terminals jumpered, turn ignition on. Check voltage between ground and PSP switch input circuit at PCM harness connector terminal. If voltage reading is 10 volts or greater, go to next step. If voltage reading is not 10 volts or greater, go to step 12 .
7. Check PSP switch input harness connector terminal at PCM connector C1. Repair as necessary. If harness connector terminals are okay, go to step 17 .
8. Turn ignition on, with engine off. Disconnect PSP switch harness connector. If scan tool displays NORMAL, go to next step. If scan tool does not display NORMAL, go to step 11 .
9. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Turn ignition on. Check voltage between ground and PSP switch input circuit at PCM harness connector C1. If voltage reading is 0.5 volt or less, go to step 7 . If voltage reading is not 5 volts or less, go to step 13 .
10. Check fuse. If fuse is blown, go to step 14 . If fuse is not blown, go to step 15 .
11. Check terminal contacts at PSP switch. Repair as necessary. If terminal contacts are okay, go to step 16 .
12. Repair open or short in PSP switch input circuit between PCM harness connector and PSP switch harness connector.
13. Repair short to voltage in PSP switch input circuit between PCM harness connector and PSP switch harness connector.
14. Replace faulty fuse and check/repair short in ignition circuit to PSP switch.
15. Repair open in ignition circuit to PSP switch.
16. Replace PSP switch.
17. Replace PCM. Program replacement PCM using required equipment.

Check for intermittent contact at PSP switch or stretching of harness causing an intermittent open.

DTC P0560: BATTERY VOLTAGE OUT OF RANGE-HIGH OR LOW (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors ignition voltage on the ignition circuit to PCM when ignition is on. This DTC detects an unstable ignition voltage to PCM. DTC will set due to an internal PCM failure. The PCM can determine if battery voltage is out of range (high or low).

Check for DTCs P0562 and P0563. If these DTCs are not present, replace PCM. Program replacement PCM using required equipment. If DTC P1635 is also present, diagnose this DTC first.

DTC P0560: SYSTEM VOLTAGE (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

ECM continuously monitors system voltage. Since voltages that are less than 9 volts or greater than 16 volts could cause improper system operation and/or component damage, ECM operates in a default mode if an ECM voltage DTC is set. If system voltage is low, ECM will raise idle speed to increase alternator output. If system voltage is high, ECM disables most outputs to protect components.

Serial data is disrupted when system voltage is below 9 volts or above 16 volts. A scan tool may not display data if system voltage is outside this range. Because of this, a DVOM must be used to monitor system voltage when checking to see if fault is currently present.

Conditions required to set DTC are

1. ECM senses system voltage less than 9 volts for at least 2 seconds.
2. ECM senses system voltage less than 2.54 volts for at least 1 second.
3. ECM senses system voltage greater than 16 volts for at least 1 second.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, check system voltage. If scan tool indicates voltage greater than 16 volts, go to next step. If scan tool indicates voltage less than 16 volts, go to step 4 .
3. Start engine. Turn all accessories off. Raise engine RPM to at least 2500 RPM. Using DVOM, measure voltage at battery. If battery voltage is greater than 16 volts, repair starting or charging system. If battery voltage is not greater than 16 volts, go to step 7 .
4. Allow engine to idle. Load electrical system by turning on headlights and high blower. Using a DVOM, check voltage at battery. If battery voltage is less than 9 volts, repair starting or charging system. If battery voltage is not less than 9 volts, go to next step.
5. Turn ignition off. Disconnect ECM harness connector. ECM is located in engine compartment relay center. Turn ignition on, with engine off. Using DVOM, check voltage at ECM harness connector battery feed circuit. If voltage reading is less than 9 volts, go to step 9 . If voltage reading is greater than 9 volts, go to next step.
6. Check for faulty connections at ECM. Repair as necessary. After repairs, go to step 10 . If connections are okay, go to next step.
7. Reconnect ECM harness connector (if previously disconnected). Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0560 is set, go to next step. If DTC P0560 is not set, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
8. Replace ECM. NEW ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
9. Repair high resistance in battery feed circuit to ECM. After repairs, go to next step.
10. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0560 is set, go to step 2 . If DTC P0560 is not set, go to next step.
11. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

Extremely low voltage (less than 7.5 volts) may cause loss of serial data and MIL may not function. Low system voltage may cause other DTCs to set.

Using FREEZE FRAME data may aid in locating intermittent condition. If DTC cannot be duplicated, review information in FREEZE FRAME. Try to operate vehicle within same FREEZE FRAME conditions. This may help to recreate malfunction.

DTC P0560: SYSTEM VOLTAGE (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors system voltage on PCM ignition feed circuit. If system voltage is out of range, DTC P0560 will set.

Conditions required to set DTC are

1. Engine is running.
2. System voltage monitored at PCM ignition feed circuit is less than 9 or greater than 16 volts.
3. Conditions present for longer than 25 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If DTC P1635 is also set, diagnose DTC P1635 before proceeding. If DTC is not set, go to next step.
3. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 5 .
4. Read and record FAILURE RECORDS data for DTC P0560. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0560 test runs. If scan tool displays DTC P0560 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0560 FAILED THIS IGN, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Install DVOM between battery terminals. Monitor DVOM while running engine at greater than 1000 RPM. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 7 .
6. Turn headlights on and place A/C switch on high. Monitor DVOM while running engine at greater than 2000 RPM. If voltage reading is 10-16 volts, go to step 8 . If voltage reading is not 10-16 volts, go to next step.
7. Turn ignition off. Disconnect generator electrical connector. Turn ignition on. Connect DVOM between generator harness connector control circuit and engine ground. Using scan tool, command GEN L TERM on. If voltage reading is 10-16 volts, go to step 12 . If voltage reading is not 10-16 volts, go to step 10 .
8. Compare IGNITION 1 voltage display on scan tool with DVOM voltage reading. If both values are close, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If both values are not close, go to next step.
9. Check PCM ignition feed circuit for poor connection between ignition switch and PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
10. Check generator control circuit for open or short to ground between generator and PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to next step.
11. Check generator control circuit for faulty connection at PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
12. Check generator control circuit for faulty connection at generator. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Clear DTCs. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, repair is complete. If voltage reading is not as specified, return to step 2 .

Check for faulty connections or damaged harness. Observe IGNITION 1 display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0560: SYSTEM VOLTAGE (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors system voltage on PCM ignition feed circuit. If system voltage is out of range, DTC P0560 will set. DTC will also set when system voltage monitored at PCM ignition feed circuit is less than 9 volts or greater than 16 volts and if these conditions are present for longer than 25 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If DTC P1635 is also set, diagnose DTC P1635 before proceeding. If DTC P1635 is not set, go to next step.
3. Start and operate engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG 2 DATA LIST. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 5 .
4. Read and record FAILURE RECORDS data for DTC P0560. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0560 test runs. If scan tool displays DTC P0560 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0560 FAILED THIS IGN, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Install a DVOM between battery terminals. Monitor DVOM while running engine at greater than 1000 RPM. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 7 .
6. Turn headlights on and place A/C switch on high. Monitor DVOM while running engine at greater than 2000 RPM. If voltage reading is 10-16 volts, go to step 8 . If voltage reading is not 10-16 volts, go to next step.
7. Turn ignition off. Disconnect generator electrical connector. Turn ignition on. Connect DVOM between generator harness connector control circuit and engine ground. Using scan tool, command GEN L TERM on. If voltage reading is 10-16 volts, go to step 12 . If voltage reading is not 10-16 volts, go to step 10 .
8. Compare IGNITION 1 voltage display on scan tool with DVOM voltage reading. If both values are close, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If both values are not close, go to next step.
9. Check PCM ignition feed circuit for poor connection between ignition switch and PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
10. Check generator control circuit for open or short to ground between generator and PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to next step.
11. Check generator control circuit for faulty connection at PCM. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
12. Check generator control circuit for faulty connection at generator. If problem is found, repair as necessary. After repairs, go to step 14 . If no problem is found, diagnose charging system.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Clear DTCs. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, go to next step. If voltage reading is not as specified, return to step 2 .
15. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for faulty connections or damaged harness. Observe IGNITION 1 display on scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0560: SYSTEM VOLTAGE (3.8L "C", "F", "G", "H" & "W" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors system voltage on PCM ignition feed circuit. If system voltage is out of range, DTC P0560 will set.

Conditions required to set DTC are

1. Engine is running.
2. System voltage monitored at PCM ignition feed circuit is less than 9 or greater than 16 volts.
3. Conditions present for greater than 2 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If DTC P1635 is also set, diagnose DTC P1635 before proceeding. If DTC is not set, go to next step.
3. Start and operate engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, go to step 5 . If voltage reading is not 10-16 volts, go to next step.
4. Read and record FAILURE RECORDS data for DTC P0560. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC while operating vehicle. Continue operating vehicle until DTC P0560 test runs. If scan tool displays DTC P0560 FAILED THIS IGN, go to next step. If scan tool does not display DTC P0560 FAILED THIS IGN, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
5. Install DVOM between battery terminals. Monitor DVOM while running engine at greater than 1000 RPM. If voltage reading is 10-16 volts, go to next step. If voltage reading is not 10-16 volts, go to step 7 .
6. Turn headlights on and place A/C switch on high. Monitor DVOM while running engine at greater than 2000 RPM. If voltage reading is 10-16 volts, go to step 8 . If voltage reading is not 10-16 volts, go to next step.
7. Turn ignition off. Disconnect generator electrical connector. Turn ignition on. Connect DVOM between generator harness connector control circuit and engine ground. Using scan tool, command GEN L TERM on. If voltage reading is 10-16 volts, go to step 12 . If voltage reading is not 10-16 volts, go to step 10 .
8. Compare IGNITION 1 voltage display on scan tool with DVOM voltage reading. If both values are close, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If both values are not close, go to next step.
9. Check PCM ignition feed circuit for poor connection between ignition switch and PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
10. Check generator control circuit for open or short to ground between generator and PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to next step.
11. Check generator control circuit for faulty connection at PCM. Repair as necessary. After repairs, go to step 14 . If no problem is found, go to step 13 .
12. Check generator control circuit for faulty connection at generator. Repair as necessary. After repairs, go to step 14 . If no problem is found, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Clear DTCs. Start and run engine at greater than 1000 RPM. Using scan tool, observe IGNITION 1 voltage on ENG. 2 DATA LIST. If voltage reading is 10-16 volts, repair is complete. If voltage reading is not 10-16 volts, return to step 2 .

Check for faulty connections or damaged harness. Observe scan tool IGNITION 1 voltage display while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P0560: SYSTEM VOLTAGE LOW (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors system voltage on ignition feed circuit to PCM harness connector C1. DTC will set if this voltage drops to less than 10 volts, with engine running at greater than 500 RPM. If ignition voltage is zero volts (open circuit), engine will not operate since PCM does not have the ignition feed voltage to operate.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, note IGNITION 1 voltage reading. Compare this voltage to voltage displayed by the Instrument Panel Cluster (IPC) message center. Scan tool and IPC voltage difference should be within 0.5 volt. If difference is greater than 0.5 volt, go to next step. If scan tool and IPC voltage is within 0.5 volt, diagnose charging system. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Using DVOM, check voltage between ground and PCM fuse. Scan tool and DVOM voltage difference should be within 0.5 volt. If voltage difference is greater than 0.5 volt, go to next step. If voltage reading is within 0.5 volt or the same, diagnose charging system.
4. Check for high resistance in ignition feed circuit to PCM. Repair circuit as necessary. If circuit is okay, go to next step.
5. Check terminal contact PCM harness connectors C1 and C2. Repair as necessary. If terminal contacts are okay, go to next step.
6. Replace PCM. Program replacement PCM using required equipment.

Normal running system voltage is about 15 volts. A loose or faulty connection at generator "L" terminal may cause DTC to set intermittently.

DTC P0561: BATTERY VOLTAGE UNSTABLE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors ignition voltage on the ignition circuit to PCM when ignition is on. This DTC detects an unstable ignition voltage to PCM. DTC will set if ignition voltage changes are greater than 3 volts instantaneously. PCM monitors system voltage continuously when the engine is running. System must fail twice per ignition cycle in order to set DTC.

If DTC P1635 is also present, diagnose this DTC first. A short to battery voltage on the 5-volt reference line will cause a false set of DTC P0560, P0561 or P0563.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This data can be used to duplicate a problem.

Wiggle PCM harness connector and watch scan tool to see if battery voltage changes abruptly. Check PCM harness connector for tightness. Wiggle ignition switch harness connector and watch if ignition voltage changes abruptly. Lightly tap on PCM and watch for changes in ignition voltage. Check battery positive connection at alternator and battery for tightness. Check IGN 4 and PCM 1 fuses in the underhood fuse/relay block.

DTC P0562 OR P0563: SYSTEM VOLTAGE OUT OF RANGE-LOW OR HIGH (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM internally monitors ignition voltage on the ignition reference circuit. PCM monitors system voltage continuously when engine is running. The system must fail twice per ignition cycle in order to set a DTC.

DTC P0562 will set when battery voltage at the PCM is less than 11 volts, with engine running.

DTC P0563 will set when battery voltage at the PCM is greater than 17 volts, with engine running.

Note. If DTC P1635 is present, diagnose P1635 first.

1. Install scan tool. Start engine and read battery voltage. If voltage reading is 11-17 volts, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If voltage reading is not 11-17 volts, go to next step.
2. If voltage reading is greater than 11 volts, go to next step. If voltage reading is less than 11 volts, check for blown fusible link, discharged battery, high resistance in ignition circuit to PCM, poor PCM grounds or charging system problem.
3. Check voltage at battery with engine at 2000 RPM. If voltage reading is greater than 17 volts, check for overcharging problem in charging system. If voltage problem is less than 17 volts, locate and repair short to battery voltage in 5-volt reference circuit to PCM.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This data can be used to duplicate a problem.

This DTC must also set if the vehicle is used to jump start another vehicle that has a dead battery. Check fusible link between generator and starter for corrosion or blown fusible link. If fusible link is blown, check charging system first. Check IGN 4 and PCM 1 fuses located in underhood fuse/relay block.

DTC P0562: SYSTEM VOLTAGE LOW (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Powertrain Control Module (PCM) monitors system voltage on ignition feed circuit terminals to PCM. If voltage is less than calibrated value, DTC will set.

Conditions for setting DTC

1. System voltage less than 10 volts for 240 seconds.
2. Engine speed greater than 1300 RPM.
3. Fault is present for greater than 4 minutes.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Increase engine speed to 1400 RPM. Load electrical system (turn on headlights, high blower, etc.). Using scan tool, check ignition voltage. If voltage reading is less than 10 volts, go to next step. If voltage reading is not less than 10 volts, go to step 8 .
3. Ensure engine speed is still at 1400 RPM. Using DVOM, check voltage at battery. If voltage reading is greater than 12 volts, go to next step. If voltage reading is not greater than 12 volts, repair charging system as necessary.
4. Turn ignition off. Disconnect PCM harness connector. Turn ignition on, with engine off. Using DVOM, check voltage between ground and ignition feed circuit No. 2 terminal at PCM connector. If voltage reading is greater than 10 volts, go to next step. If voltage reading is not greater than 10 volts, go to step 6 .
5. Check for poor connections at PCM harness connector terminals. Repair as necessary. After repairs, go to step 8 . If connector terminals are okay, go to step 7 .
6. Repair poor connection in ignition feed circuit No. 2. After repairs, go to step 8 .
7. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
9. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

If DTC sets when an accessory is operated, check for poor connection or excessive current draw.

DTC P0562: SYSTEM VOLTAGE LOW (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM continuously monitor system voltage. System voltage information is taken from PCM's ignition feed circuits. Since voltages of less than 8 volts or greater than 18 volts could cause improper system operation and/or component damage, PCM will operate in default mode if DTC is set.

If system voltage is too low, PCM will raise idle speed to increase generator output. If system voltage is too high, PCM disables most outputs to protect hardware. Scan tool will display data if system voltage is outside this range. DVOM should be used to monitor system voltage when checking if fault is currently present.

DTC will set when PCM senses system voltage at less than 8 volts and condition is present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, check if DTC P1637 is also set. If DTC P1637 is set, go to DTC P1637 test. If DTC P1637 is not set, monitor IGN 1 voltage using scan tool. If battery voltage is present, diagnose charging system. If battery voltage is not present, go to next step.
3. Check ECM 1 fuse. If fuse is open, go to step 6 . If fuse is okay, go to next step.
4. Turn ignition off. Disconnect PCM harness connector C1. Turn ignition on. Using DVOM, check voltage at PCM ignition feed circuit terminal. If battery voltage is present, go to step 7 . If battery voltage is not present, go to next step.
5. Check resistance of ignition feed circuit. If resistance is less than 5 ohms, go to step 7 . If resistance is not less than 5 ohms, go to next step.
6. Repair open or short to ground in ignition feed circuit to PCM. After repairs, go to step 9 .
7. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to next step.
8. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

An extremely low system voltage (less than 7 volts) may cause loss of serial data and MIL may not activate. An open ignition feed circuit will cause a no-start and MIL will not illuminate. Low system voltage may cause DTC to set.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0562: SYSTEM VOLTAGE LOW (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM continuously monitor system voltage. System voltage information is taken from PCM's ignition feed circuits. Since voltages of less than 8 volts or more than 17.1 volts could cause improper system operation and/or component damage, PCM will operate in default mode if DTC is set.

If system voltage is too low, PCM will raise idle speed to increase generator output. If system voltage is too high, PCM disables most outputs to protect hardware. Class 2 serial data is shut down when system voltage is less than 9.2 volts or more than 16 volts. Scan tool will display data if system voltage is outside this range. DVOM should be used to monitor system voltage when checking if fault is currently present.

DTC will set when the following conditions are present

1. Engine running longer than 10 seconds.
2. Engine speed greater than 1000 RPM.
3. Vehicle speed greater than 5 MPH.
4. PCM senses system voltage less than 8 volts.
5. Conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Turn headlights on and blower fan to high, to load electrical system. Using DVOM, check battery voltage at battery. If battery voltage is less than 8 volts, check/diagnose charging system. If battery voltage is not less than 8 volts, go to next step.
3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using DVOM, check voltage at PCM ignition feed terminal. If voltage reading is less than 8 volts, go to step 7 . If voltage reading is not less than 8 volts, go to next step.
4. Check for faulty connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
5. Turn ignition off. Reconnect PCM harness connector. Turn ignition on. Using scan tool, select ENG DTC, DTC INFO function. If any DTCs are displayed, diagnose affected DTCs first. If DTCs are not present, go to next step.
6. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 8 .
7. Repair ignition feed circuit to PCM as necessary. After repairs, go to next step.
8. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0562. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
9. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

An extremely low system voltage (less than 7 volts) may cause loss of serial data and MIL may not activate. An open ignition feed circuit will cause a no-start and MIL will not illuminate. Low system voltage may cause DTC to set.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0563: SYSTEM VOLTAGE HIGH (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Powertrain Control Module (PCM) monitors system voltage on ignition feed circuit terminals to PCM. If voltage is greater than calibrated value, DTC will set.

For duplication of DTC, ensure system voltage is greater than 17 volts.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn all accessories off. Start and increase engine speed to 1400 RPM. Using scan tool, check ignition voltage. If voltage reading is greater than 17 volts, go to next step. If voltage reading is not greater than 17 volts, go to step 5 .
3. Increase engine speed to 2000 RPM. Using DVOM, check voltage at battery. If voltage reading is less than 17 volts, go to next step. If voltage reading is not less than 17 volts, repair charging system as necessary.
4. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, no problem is indicated at this time. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .

If DTC sets when an accessory is operated, check for poor connection or excessive current draw.

DTC P0563: SYSTEM VOLTAGE HIGH (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors system voltage on ignition feed circuit to PCM harness connector C1. DTC will set if this voltage is greater than 16 volts for 6 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, note IGNITION 1 voltage reading. Compare this voltage to voltage displayed by the Instrument Panel Cluster (IPC) message center. If difference is greater than 0.5 volt, go to next step. If scan tool and IPC voltage is within 0.5 volt or the same, diagnose charging system. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Using DVOM, check voltage to ground on PCM fuse. If difference is greater than 0.5 volt, go to next step. If scan tool and DVOM voltage is the same or within 0.5 volt, diagnose charging system.
4. Check for high resistance in ignition feed circuit to PCM. Repair circuit as necessary. If circuit is okay, go to next step.
5. Check terminal contact PCM harness connectors C1 and C2. Repair as necessary. If terminal contacts are okay, go to next step.
6. Replace PCM. Program replacement PCM using required equipment.

Normal running system voltage is about 15 volts. A loose or faulty connection at generator "L" terminal may cause DTC to set intermittently.

DTC P0563: SYSTEM VOLTAGE HIGH (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM continuously monitor system voltage. System voltage information is taken from PCM's ignition feed circuits. Since voltages of less than 8 volts or greater than 18 volts could cause improper system operation and/or component damage, PCM will operate in default mode if DTC is set.

If system voltage is too low, PCM will raise idle speed to increase generator output. If system voltage is too high, PCM disables most outputs to protect hardware. Scan tool will display data if system voltage is outside this range. DVOM should be used to monitor system voltage when checking if fault is currently present.

DTC will set when PCM senses the system voltage is greater than 18 volts for a period of 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If DTC P1635 is set, diagnose DTC P1635 first. If DTC P1635 is not set, turn off all accessories. Start and operate engine at greater than 2000 RPM. Using DVOM, check battery voltage at battery. If battery voltage is less than 18 volts, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If battery voltage is not less than 18 volts, go to next step.
3. Repair charging system. After repairs, go to next step.
4. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
5. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check generator voltage sense circuit for high resistance or loose connections, causing intermittent overcharging condition.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0563: SYSTEM VOLTAGE HIGH (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM continuously monitor system voltage. System voltage information is taken from PCM's ignition feed circuits. Since voltages of less than 8 volts or more than 17.1 volts could cause improper system operation and/or component damage, PCM will operate in default mode if DTC is set.

If system voltage is too low, PCM will raise idle speed to increase generator output. If system voltage is too high, PCM disables most outputs to protect hardware. Class 2 serial data is shut down when system voltage is less than 9.2 volts or more than 16 volts. Scan tool will display data if system voltage is outside this range. DVOM should be used to monitor system voltage when checking if fault is currently present.

DTC will set when the following conditions are present

1. Engine running.
2. PCM senses system voltage greater than 17.1 volts.
3. Conditions met for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn off all accessories. Start and operate engine at greater than 2000 RPM. Using DVOM, check battery voltage at battery. If battery voltage is less than 17.1 volts, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If battery voltage is not less than 17.1 volts, go to next step.
3. Repair charging system. After repairs, go to next step.
4. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
5. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check generator voltage sense circuit for high resistance or loose connections, causing intermittent overcharging condition.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0565: CRUISE SWITCH CIRCUIT MALFUNCTION (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Command state voltage levels are divided through a resistor network from ignition voltage provided through the cruise control fuse. The network consists of resistors both in the cruise control switch and internal PCM. If the voltage level is within an acceptable window for all 3 switches, the PCM decodes the command. If voltages are outside the windows, DTC will set.

DTC will also set under the following parameters

1. Cruise switch in ON position - Voltage is less than 0.5 volt or greater than one volt at PCM cruise switch input circuit.
2. Cruise switch in RESUME/ACCEL position - Voltage less than 1.2 volts or greater than 1.7 volts at PCM cruise switch input circuit.
3. Cruise switch in SET/COAST position - Voltage less than 3 volts or greater than 3.5 volts at PCM cruise switch input circuit.

1. Install scan tool. Start engine. Turn off cruise control switch. Check if DTC P0565 is active. If DTC is active, go to next step. If DTC is not active, go to step 4 .
2. Turn engine off. Disable air bag system. See appropriate AIR BAG RESTRAINT SYSTEMS article in ACCESSORIES & EQUIPMENT. Remove driver's side inflator module. Disconnect harness connector from cruise control switch. Start engine. Check if DTC P0565 is active. If DTC is active, go to next step. If DTC is not active, replace cruise control switch.
3. Turn engine off. Remove upper steering column shroud. Disconnect Black 4-wire air bag roll connector. Start engine. Check if DTC P0565 is active. If DTC is active, check cruise switch input circuit to PCM for short to voltage. If circuit is okay, replace PCM. If DTC is not active, replace air bag roll connector.
4. Turn on cruise control switch. Check if DTC P0565 is active. If DTC is active, replace cruise control switch. If DTC is not active, go to next step.
5. Press and hold SET/COAST button for 3 seconds and release. If DTC is active when SET/COAST button is depressed, replace cruise control switch. If DTC is not active when SET/COAST button is depressed, go to next step.
6. Press and hold RESUME/ACCEL button for 3 seconds and release. Check if DTC P0565 is active. If DTC is active, replace cruise control switch. If DTC is not active, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

Check malfunction history data. Attempt to distinguish which portion of switch input was lost and try to reproduce failure. A short or open in cruise switch input circuit will result in an inoperative system. Check for intermittent connections by wiggling harness and connectors.

DTC P0567: CRUISE RESUME CIRCUIT (3.8L "F" BODY & 5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Cruise RESUME/ACCEL circuit is an input to Throttle Actuator Control (TAC) module. This input allows TAC module to control and hold a requested speed. Cruise RESUME/ACCEL switch sends ignition voltage to TAC module when switch is closed (ON). If TAC module senses voltage on this circuit when it is not expected, this DTC will set.

For duplication of DTC, ensure cruise switch is on, and RESUME/ACCEL switch has been on for more than 90 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read cruise RESUME/ACCEL switch status. Turn ignition on, with engine off. Turn cruise switch on. If scan tool displays ON, go to next step. If scan tool does not display ON, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Turn ignition off. Disconnect TAC module connector. Turn ignition on. Using appropriate jumpers from Connector Kit (J-35616-A) and a test light, front probe TAC module connector (harness side), RESUME/ACCEL switch signal circuit to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 5 .
4. Repair short to voltage in RESUME/ACCEL switch signal circuit. After repairs, go to step 6 .
5. Replace TAC module and go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0567. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for stuck RESUME/ACCEL switch or signal circuit shorted to voltage. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0568: CRUISE SET CIRCUIT (3.8L "F" BODY & 5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Cruise SET/COAST circuit is an input to Throttle Actuator Control (TAC) module. This input allows TAC module to control and hold a requested speed. Cruise SET/COAST switch sends ignition voltage to TAC module when switch is closed (ON). If TAC module senses voltage on this circuit when it is not expected, this DTC will set.

For duplication of DTC, ensure cruise switch is on, and SET/COAST switch has been on for more than 90 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read cruise SET/COAST switch status. Turn ignition on, with engine off. Turn cruise switch on. If scan tool displays ON, go to next step. If scan tool does not display ON, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .
3. Turn ignition off. Disconnect TAC module harness connector. Turn ignition on. Using appropriate jumpers from Connector Kit (J-35616-A) and a test light, front probe TAC module connector (harness side), SET/COAST switch signal circuit to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 5 .
4. Repair short to voltage in SET/COAST switch signal circuit. After repairs, go to step 6 .
5. Replace TAC module and go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0568. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for stuck SET/COAST switch or signal circuit shorted to voltage. Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0571: BRAKE SWITCH SIGNAL INVALID (1.9L SATURN)

Note. For circuit reference, see WIRING DIAGRAMS article.

DTC will set if vehicle speed has cycled from 0-37 MPH 5 times without seeing a change in brake status. If DTC P0571 is present and DTC P0572 or P0573 is not present, then the PCM has failed internally.

Verify that DTCs P0572 and P0573 are not present. If either DTCs are present, diagnose these DTCs first. If these DTCs are not present, replace PCM.

DTC P0571: CRUISE BRAKE SWITCH CIRCUIT (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Cruise control switch release is used to disable cruise control whenever brake pedal is applied. Cruise control switch is supplied power from ignition circuit at stoplight switch. The ECM supplies ground circuit for cruise control switch and stoplight switch. If brake signal is unrecognized 10 times in one second or more, DTC will set. For duplication of DTC, ensure engine is running.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Inspect fuse No. 2 (15-amp) located in fuse block. If fuse is open, go to step 6 . If fuse is okay, go to next step.
3. Disconnect cruise control switch. Turn ignition on. Using a test light connected to ground, probe cruise control switch power feed circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
4. Turn ignition off. Using a test light connected to battery positive, probe cruise release signal circuit. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
5. Check cruise release circuit for an open or short. If a problem is found, go to step 7 . If circuit is okay, go to step 9 .
6. Repair short in cruise release circuit. After repairs, go to step 10 .
7. Repair open in cruise release circuit. After repairs, go to step 10 .
8. Replace cruise control release switch. After repairs, go to step 10 .
9. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code currently on vehicle. After repairs, go to next step.
10. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0571. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

DTC P0571: CRUISE BRAKE SWITCH CIRCUIT (3.8L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Cruise Control (CC) brake switch is a normally closed switch. When CC brake switch is closed, PCM senses ignition voltage on CC brake switch signal circuit. DTC P0571 sets if PCM senses CC brake switch signal circuit voltage when CC brake switch should be open.

DTC will set when the following conditions are present

1. Engine speed greater than 700 RPM.
2. Engine operating more than 2 seconds.
3. Wheel speed greater than 30 MPH to enable diagnostic. Diagnostic will be disabled at less than 10 MPH.
4. PCM detects switch is not toggling as compared with other brake switch inputs.
5. Conditions are met for 20 accel/decel cycles.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Start engine. Using scan tool, monitor cruise release switch. Depress brake pedal half way. If scan tool indicated RELEASED, and then APPLIED, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not indicate RELEASED, and then APPLIED, go to next step.
3. Check A/C CRUISE fuse (15-amp) located in underhood electrical center. If fuse is open, go to next step. If fuse is okay, go to step 6 .
4. Disconnect cruise clutch switch. Using test light connected to ground, probe ignition feed circuit at cruise clutch switch harness connector. If test light illuminates, go to step 17 . If test light does not illuminate, go to next step.
5. Disconnect cruise brake switch. Using test light connected to battery positive, probe ignition feed circuit, and then signal circuit at cruise brake switch harness connector. If test light illuminates for either circuit, go to step 26 . If test light does not illuminate for either circuit, go to next step.
6. Check adjustment of cruise clutch switch. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . Adjust if necessary. After adjustment, go to step 27 . If adjustment is okay, go to next step.
7. Check adjustment of cruise clutch switch. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . Adjust if necessary. After adjustment, go to step 27 . If adjustment is okay, go to next step.
8. Disconnect cruise clutch switch. Measure voltage between ground and ignition feed circuit at cruise clutch switch harness connector. If voltage is battery voltage, go to next step. If voltage is not battery voltage, go to step 18 .
9. Measure voltage between ground and ignition feed circuit at cruise clutch switch harness connector. If voltage is near zero volts, go to next step. If voltage is not near zero volts, go to step 19 .
10. Remove cruise clutch switch. Check for continuity across switch while toggling it by hand. If switch toggles between continuity and open, go to next step. If switch continuity does not toggle, go to step 20 .
11. Disconnect cruise brake switch. Check for continuity in cruise brake feed circuit between cruise clutch switch and cruise brake switch. If continuity is present, go to step 13 . If continuity is not present, go to step 21 .
12. Disconnect cruise brake switch. Measure voltage between ground and ignition feed circuit at cruise brake switch circuit harness connector. If voltage is battery voltage, go to next step. If voltage is not battery voltage, go to step 22 .
13. Measure voltage between ground and cruise control release switch signal circuit at cruise brake switch harness connector. If voltage is near zero volts, go to next step. If voltage is not near zero volts, go to step 23 .
14. Remove cruise brake switch. Check for continuity across switch while toggling it by hand. If switch toggles between continuity and open, go to next step. If switch continuity does not toggle, go to step 24 .
15. Check for an open in cruise control release switch signal circuit. Repair as necessary. After repairs, go to step 27 . If circuit is okay, go to next step.
16. Check for poor connections. Repair as necessary. After repairs, go to step 27 . If connections are okay, go to step 25 .
17. Repair short to ground in clutch switch ignition feed circuit. After repairs, go to step 27 .
18. Repair open in clutch switch ignition feed circuit. After repairs, go to step 27 .
19. Repair short to voltage between cruise clutch switch and PCM. After repairs, go to step 27 .
20. Replace cruise clutch switch. After repairs, go to step 27 .
21. Repair open in cruise brake switch ignition feed circuit between cruise brake switch and cruise clutch switch. After repairs, go to step 27 .
22. Repair open in cruise brake switch ignition feed circuit. After repairs, go to step 27 .
23. Repair short to voltage in cruise brake switch signal circuit. After repairs, go to step 27 .
24. Replace cruise brake switch. After repairs, go to step 27 .
25. Replace PCM. Program replacement PCM using required equipment. After repairs, go to step 27 .
26. Repair short to ground in circuit that illuminated test light. After repairs, go to step 27 . If circuits are okay, go to step 25 .
27. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0571. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
28. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are present, system is okay.

With brake pedal depressed, insert CC brake switch into retainer until switch body seats in retainer. A "clicking" sound should be heard as threaded portion of switch is pushed through retainer. Slowly pull brake pedal fully rearward against stop until "clicks" are no longer heard.

DTC P0571: CRUISE BRAKE SWITCH CIRCUIT (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Cruise Control (CC) brake switch is a normally closed switch. When CC brake switch is closed, PCM senses ignition voltage on CC brake switch signal circuit. DTC P0571 sets if PCM senses CC brake switch signal circuit voltage when CC brake switch should be open.

DTC will set when the following conditions are present

1. Engine speed greater than 700 RPM.
2. Engine operating more than 2 seconds.
3. Wheel speed greater than 30 MPH to enable diagnostic. Diagnostic will be disabled at less than 10 MPH.
4. PCM detects voltage on cruise control brake switch circuit when cruise control brake switch should be open.
5. Conditions met for 1.5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, read CC brake switch status. Depress brake pedal about 1/4 way down. If scan tool displays APPLIED, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not display APPLIED, go to next step.
3. Check CC brake switch adjustment. Adjust if necessary. After adjustment, go to step 9 . If adjustment is okay, go to next step.
4. Turn ignition off. Disconnect CC brake switch connector. Turn ignition on. Using scan tool, read CC brake switch status. If scan tool displays APPLIED, go to next step. If scan tool does not display APPLIED, go to step 8 .
5. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Install Brown harness connector from Connector Kit (J-35616-A) into CC brake switch signal circuit at PCM connector (harness side). Using a DVOM, check voltage on CC brake switch signal circuit. If voltage reading is greater than 0.5 volt, go to next step. If voltage reading is not greater than 0.5 volt, go to step 8 .
6. Repair short to voltage in brake switch signal circuit. After repairs, go to step 9 .
7. Replace CC brake switch. After replacing brake switch, go to step 9 .
8. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0571. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If no problem can be found with ignition feed circuit to CC brake switch, inspect IGN 1 mini relay for proper operation. Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0572: BRAKE SWITCH-LOW VOLTAGE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The brake switch is normally closed, supplying 12 volts to PCM at terminal J1C14, when ignition is on and brake off. A scan tool should display ON when brake pedal is depressed and should read OFF with brake pedal released.

DTC will set if no voltage has been seen at PCM terminal J1C14 circuit when vehicle has cycled 2 times from 0-37 MPH.

1. Install scan tool. Using scan tool, observe brake status in PCM while depressing and releasing brake pedal. If scan tool indicates brake status changes on and off, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not indicate brake status on and off, go to next step.
2. If vehicle is equipped with A/T, check if TCM data shows the correct brake status. If correct brake status is shown, replace PCM. If incorrect brake status is shown, go to next step.
3. Check for faulty cruise control fuse. If fuse is okay, go to next step. If fuse is faulty, check circuits to cruise/brake switch for short to ground. If circuits are shorted, repair as necessary and replace fuse. If circuits are okay, replace fuse.
4. Turn ignition on. Check voltage supply to underdash fuse/relay block. If battery voltage is present, go to next step. If battery voltage is not present, repair open in voltage supply to underhood fuse/relay block.
5. Disconnect cruise/brake switch harness connector. Jumper brake switch harness connector terminals. Using scan tool, observe brake indication. If scan tool indicates that brake is on, go to next step. If scan tool does not indicate that brake is on, check for a misadjusted or faulty cruise/brake switch.
6. Remove jumper wire. Using a fused jumper wire connected to battery voltage, connect jumper to cruise/brake switch harness connector terminal "C". If scan tool indicates that brake is on, go to next step. If scan tool does not indicate that brake is on, check for open in circuit between fuse block and cruise/brake switch.
7. Turn ignition off. Reconnect brake switch harness connector. Disconnect PCM harness connector J1. Turn ignition on. Check for battery voltage at PCM harness connector terminal J1C14. If battery voltage is present, check for terminal tightness or faulty PCM. If battery voltage is not present, repair open in circuit.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This data can be used to duplicate a problem. This DTC could also set by vehicle coming to a complete stop without using the service brakes.

DTC P0573: BRAKE SWITCH STUCK CLOSED-HIGH VOLTAGE (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

The brake switch is normally closed, supplying 12 volts to PCM at terminal J1C14, when is ignition is on and brake off. A scan tool should display ON when brake pedal is depressed and should read OFF with brake pedal released.

DTC will set if voltage at PCM terminal J1C14 is always 12 volts when vehicle has cycled 2 times from 0-37 MPH.

1. Install scan tool. Using scan tool, observe PCM brake switch status while depressing and releasing brake pedal. If scan tool indicates that brake status changes on and off, problem is intermittent. See «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If scan tool does not indicate that brake status changes on and off, go to next step.
2. Turn ignition on, with engine off. Disconnect brake switch harness connector. Observe brake indication on scan tool. If scan tool indicates that brake is off, replace brake switch. If scan tool indicates that the brake is not off, go to next step.
3. Turn ignition off. Disconnect PCM harness connector J1. Turn ignition on. Remove brake switch circuit (terminal J1C14) from PCM harness connector. Reconnect PCM harness connector. If scan tool indicates that brake is off, repair short to voltage in brake switch circuit to PCM or cruise control module. If scan tool indicates that brake is not off, PCM is internally shorted to voltage. Replace PCM.

When attempting to diagnose an intermittent problem, use scan tool to review malfunction history diagnostic information. This data can be used to duplicate a problem. DTC could also be set by vehicle coming to a complete stop without using service brakes. A blown cruise control fuse will also cause DTC to set.

When serial data messages are not properly transmitted between the PCM and TC, DTC will set.

Reprogram PCM. Record any DTCs and diagnose affected DTCs. If DTC P0600 resets, replace PCM.

This DTC will set when the PCM determines that the PCM RAM is faulty.

Record any DTCs and diagnose affected DTCs. If DTC P0601 resets, replace PCM. Program replacement PCM using required equipment.

DTC P0601: PCM MEMORY (2.2L "J" BODY & "S" SERIES & 2.4L "J" & "N" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Electronically Erasable Programmable Read Only (EEPROM) is used to contain program information and calibrations required for engine, transmission and powertrain diagnostics operation. Powertrain Control Module (PCM) uses a value called a checksum for error detection of software. Checksum is a value that is equal to all numbers in software added together. PCM adds all values in the software and if that value does not equal the checksum value, a DTC will set.

For duplication of DTC, PCM must detect more than 3 incorrect checksums.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
3. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
4. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

DTC P0601: ECM MEMORY (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

ECM contains data which is essential to engine operation. ECM continuously checks integrity of this data. For duplication of DTC, ECM must determine that an internal data test did not pass.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
3. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0601 is set, go to step 2 . If DTC P0601 is not set, go to next step.
4. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

Replace ECM even if this DTC exists only in history.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. If PCM detects an internal program fault (check sum error), DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

Only possible repair is replacement and programming of PCM.

DTC P0601: VCM MEMORY (3.5L "W" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM uses an EEPROM. The EEPROM contains program information and calibrations required to powertrain diagnostics operation. EEPROM is not replaceable. When PCM is replaced or a calibration update is required, PCM must be programmed using approved equipment.

System is continuously tested during crank or running conditions. DTC will set when PCM detects a problem with internal programming.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P0601 indicates that the contents of the EEPROM changed since PCM was programmed. The only possible repair is PCM replacement. Program replacement PCM using required equipment.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. If PCM detects an internal program fault (check sum error), DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

Only possible repair is replacement and programming of PCM.

The PCM EPROM contains data essential in running engine and transaxle. This test check the integrity of the data. The EPROM data is divided into 2 halves or sides in the EPROM. The integrity of the data is checked by adding up the data in all locations of the EPROM. This is called the checksum. If checksum does not equal to what it should, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment.

DTC P0601: VCM MEMORY (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM program memory contains data which is essential to running engine and transmission. VCM continuously checks integrity of this data.

Conditions for setting DTC

1. VCM unable to correctly read data from flash memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Replace VCM even if DTC only exists as a history code.

DTC P0601: VCM MEMORY (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

VCM program memory contains data which is essential to running engine and transmission. VCM continuously checks integrity of this data. If VCM is unable to correctly read data from flash memory, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Replace VCM even if DTC only exists as a history code.

DTC P0601: PCM MEMORY (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM EEPROM contains data which is essential for running engine and transmission. PCM continuously checks integrity of this data. DTC will set when PCM is unable to correctly read data from flash memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Replace PCM even if DTC only exists as a history code.

DTC P0601: PCM MEMORY (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM EEPROM contains data which is essential to running engine and transmission. PCM continuously checks integrity of this data.

DTC will set when the following conditions are present

1. Ignition switch in CRANK or RUN position.
2. PCM is powered up.
3. PCM unable to correctly read data from flash memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Replace PCM even if DTC only exists as a history code.

This DTC will set if the PCM is not programmed correctly.

Reprogram PCM. Record any DTCs and diagnose affected DTCs. If DTC P0602 resets, replace PCM. Program replacement PCM using required equipment.

Electronically Erasable Programmable Read Only (EEPROM) is used to contain program information and calibrations required for engine, transmission and powertrain diagnostic operation. EEPROM program can be updated by reprogramming Powertrain Control Module (PCM).

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. If PCM was just replaced, go to next step. If PCM was not just replaced, go to step 4 .
3. Program replacement PCM using required equipment. If DTC resets, attempt to reprogram PCM again (maximum of 3 times). If DTC still resets, go to next step. If DTC does not reset, go to step 5 .
4. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
5. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
6. If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

This DTC indicates that ECM's internal EEPROM has not been flashed with any vehicle software, or an error occurred during programming.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash ECM with correct software. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
3. Verify that equipment being used is functioning properly and that all cable connections are clean and tight. Attempt to flash ECM again. If DTC P0602 resets, go to next step. If DTC P0602 does not reset, go to step 5 .
4. Replace ECM, then go to step 2 .
5. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0602 is set, go to step 2 . If DTC P0602 is not set, go to next step.
6. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. DTC will set if PCM does not contain correct program(s) required to operate vehicle.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using special equipment, program PCM with correct software. Using scan tool, retest for DTC P0602. If DTC P0602 sets, go to next step. If DTC does not set, system is okay.
3. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

Electronically Erasable Programmable Read Only (EEPROM) is used to contain program information and calibrations required for powertrain diagnostic operation. EEPROM is not replaceable. When PCM is replaced or a required calibration update is required, PCM must be programmed using approved equipment.

DTC will set when PCM does not contain the correct program required to operate vehicle, or PCM has not been programmed.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Program replacement PCM using required equipment. After reprogramming PCM, go to next step.
3. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
4. Using scan tool, select CLEAR INFO or CLEAR DTCS function to clear DTCs. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Operate vehicle within conditions required for setting this DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates TEST RAN AND PASSED, go to next step. If scan tool does not indicate TEST RAN AND PASSED, repeat step 2 .
5. Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM uses an Electrically Erasable Programmable Read Only Memory (EEPROM). EEPROM contains program information and calibrations required for engine, transaxle, and powertrain diagnostics operation. If PCM does not contain correct program(s) required to operate vehicle, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using special equipment, program PCM with correct software. Using scan tool, retest for DTC P0602. If DTC P0602 sets, go to next step. If DTC does not set, repair is complete.
3. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, repeat OBD system check.

DTC is designed not to allow a service/replacement PCM to be installed without first flashing software into it.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash PCM with correct software. Check if DTC resets. If DTC resets, go to next step.
3. Replace PCM. Program replacement PCM using required equipment.

DTC P0602: VCM NOT PROGRAMMED (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that VCM's internal program memory has not been flashed with any vehicle software. If a replacement VCM is installed and not flashed, engine will not run. This DTC is used to indicate that engine cranks, but will not run due to an unflashed VCM.

DTC will set if no software data is present in PCM.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash VCM with current software. If DTC is reset, go to next step. If DTC does not reset, go to step 5 .
3. Verify that test equipment used is operating properly and that all connections are clean and tight. Attempt to flash VCM again. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
4. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P0602: VCM NOT PROGRAMMED (4.3L "L", "M", "S" & "T" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that VCM's internal program memory has not been flashed with any vehicle software. If a replacement VCM is installed and not flashed, engine will not run. This DTC is used to indicate that engine cranks, but will not run due to an unflashed VCM.

DTC will set if no software data is present in VCM.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash VCM with current software. If DTC is reset, go to next step. If DTC does not reset, go to step 5 .
3. Verify that test equipment used is operating properly and that all connections are clean and tight. Attempt to flash VCM again. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
4. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P0602: PCM NOT PROGRAMMED (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that PCM's internal EEPROM has not been flashed with any vehicle software. If a replacement PCM is installed and not flashed, engine will not run. This DTC is used to indicate that engine cranks, but will not run due to an unflashed PCM. DTC will set when there is no software data present in the PCM.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash PCM with current software. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
3. Verify that test equipment used is operating properly and that all connections are clean and tight. Attempt to flash PCM again. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
4. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P0602: PCM NOT PROGRAMMED (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that PCM's internal EEPROM has not been flashed with any vehicle software. If a replacement PCM is installed and not flashed, engine will not run. This DTC is used to indicate that engine cranks, but will not run due to an unflashed PCM.

DTC will set when the following conditions are present

1. Ignition switch in RUN position.
2. PCM is powered up.
3. No software data is present in PCM.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Flash PCM with current software. If DTC is reset, go to next step. If DTC does not reset, go to step 5 .
3. Verify that test equipment used is operating properly and that all connections are clean and tight. Attempt to flash PCM again. If DTC resets, go to next step. If DTC does not reset, go to step 5 .
4. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
5. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
6. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

This DTC will set when the TC non-volatile random access memory fails.

Record any DTCs and diagnose affected DTCs. If DTC P0603 resets, replace PCM. Program replacement PCM using required equipment.

The ECM has a memory area where it stores certain data it needs to save when the ignition is turned off. This area is called Keep Alive Memory. This test monitors ECM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code currently on vehicle. After repairs, go to next step.
3. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Replace ECM, even if DTC exists only as history.

The PCM has a memory area where it stores certain data it needs to save when the ignition is turned off. This area is called Keep Alive Memory. This test monitors PCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, check for other DTCs set. If other DTCs are set, diagnose affected DTCs. If other DTCs are not present, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) .

If battery has been disconnected for any reason, DTC P0603 will set. The PCM keeps a running check on the memory and if it changes, memory will reset. An intermittent loss of power or ground to PCM will cause a reset.

The VCM contains a memory area where it stores certain data it needs to save when ignition is turned off. This area is called Keep Alive Memory. This test monitors VCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC will set.

DTC will set if data from the memory location does not match test data which was saved to memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.

The VCM contains a memory area where it stores certain data it needs to save when ignition is turned off. This area is called Keep Alive Memory. This test monitors VCM's keep alive memory for a loss or unintended change of data. If such a condition occurs, DTC will set.

DTC will set if data from the memory location does not match test data which was saved to memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.

If battery was disconnected for any reason, DTC will set. VCM checks the memory at power-up. If the memory changes, it will reset. An intermittent loss of power or ground to VCM will also cause a reset.

This DTC will set when the TC non-volatile random access memory fails.

Clear DTCs. Restart engine and recheck DTCs. Record any DTCs and diagnose affected DTCs. If DTC P0604 resets, replace and program replacement PCM, using required equipment.

ECM contains data which is essential to engine operation. ECM continuously checks integrity of this data. If ECM determines that an internal data test did not pass, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing PCM, go to next step.
3. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P0604 is set, go to step 2 . If DTC P0604 is not set, go to next step.
4. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.

Replace ECM even if this DTC exists only in history.

VCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set.

Conditions for setting this DTC

1. Ignition voltage greater than 10 volts.
2. Ignition on for 5 seconds.
3. VCM is powered up.
4. VCM detects an internal microprocessor integrity fault or internal RAM test fails.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

VCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set. DTC will also set when if the data from the memory location does not match the test data which was just saved.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set. DTC will also set when the internal RAM test fails.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2.
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set. DTC will also set when the internal RAM test fails.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2.
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set.

Conditions for setting this DTC

1. Ignition voltage greater than 10 volts.
2. Ignition on for 5 seconds.
3. PCM is powered up.
4. PCM detects an internal microprocessor integrity fault or internal RAM test fails.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

This DTC will set when the TC EEPROM fails.

Clear DTCs. Restart engine. Record any other DTCs set and diagnose affected DTCs. If DTC P0605 resets, replace PCM. Program replacement PCM using required equipment.

VCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set.

Conditions for setting this DTC

1. Checksum does not match expected value.
2. VCM unable to correctly read data from boot flash memory.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

VCM performs an internal self-test on its Random Access Memory (RAM) or read/write memory. If this self-test fails, this DTC will set. This DTC will also set if the checksum does not match the expected value.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace VCM. Program replacement VCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

This DTC will set when TC determines that its microprocessor has failed.

Record all DTCs and diagnose affected DTCs. If DTC P0606 resets, replace PCM. Program replacement PCM using required equipment.

ECM contains data essential to running the engine. The ECM continuously checks integrity of this data. If ECM determines that an internal data test did not pass, DTC will set. Engine speed must be greater than 1120 RPM for ECM to run this DTC.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code currently on vehicle. After repairs, go to next step.
3. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

Replace ECM, even if this DTC exists only in history.

DTC P0606: PCM INTERNAL COMMUNICATION INTERRUPTED (3.8L "F" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that PCM has detected an internal microprocessor integrity fault.

DTC will set when the following conditions are present

1. PCM is powered up.
2. PCM detected an internal microprocessor integrity fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2.
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM has 2 internal processors, the ECM and the TCM. They are connected together and share data on an interconnect called SPI. The ECM sends sensor data to TCM. This sensor data is checked and if the difference in readings between the 2 processors is too great, DTC will set.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment.

DTC P0606: PCM INTERNAL COMMUNICATION INTERRUPTED (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

This DTC indicates that PCM has detected an internal microprocessor integrity fault.

DTC will set when the following conditions are present

1. PCM is powered up.
2. PCM detected an internal microprocessor integrity fault.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
3. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
4. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P0608: VSS OUTPUT CIRCUIT (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied to Vehicle Speed Sensor (VSS) output circuit by various components which use VSS data. PCM creates VSS output signal by rapidly grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when PCM detect that the commanded state of the driver and actual state of the control circuit do not match and this condition is present for 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support vehicle. Start engine. Disable ASR/TCS systems (if equipped). Place transmission in Drive or 3rd gear (M/T). Observe speedometer. If speedometer indicates any speed, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If speedometer does not indicate any speed, go to next step.
3. Turn ignition off. Remove underhood electrical center cover and side shield. Lift underhood electrical center to gain access to connectors. Disconnect Black 16-pin connector from electrical center. Turn ignition on, with engine off. Using DVOM, check voltage between ground and vehicle speed output circuit on female side of connector. If voltage reading is greater than 9.5 volts, go to step 6 . If voltage reading is not greater than 9.5 volts, go to next step.
4. Turn ignition off. Remove instrument panel assembly. Check continuity of vehicle speed output circuit between IPC and PCM harness connector. If continuity exists, go to next step. If continuity does not exists, go to step 8 .
5. Test continuity between battery ground and vehicle speed output circuit. If continuity exists, go to step 9 . If continuity does not exists, diagnose instrument panel assembly.
6. Turn ignition off. Disconnect PCM harness connector C2. Check continuity of vehicle speed output circuit between PCM harness connector and Black 16-pin connector to convenience center. If continuity exists, go to next step. If continuity does not exist, go to step 10 .
7. Check continuity of vehicle speed output circuit from PCM harness connector to ground. If continuity exists, go to step 11 . If continuity does not exist, go to step 12 .
8. Repair open in vehicle speed output from IPC connector to PCM harness connector. After repairs, go to step 14 .
9. Repair grounded vehicle speed sensor output circuit from IPC to PCM harness connector. After repairs, go to step 14 .
10. Repair open in vehicle speed output from PCM. After repairs, go to step 14 .
11. Repair grounded vehicle speed output circuit from PCM. After repairs, go to step 14 .
12. Check PCM harness connector for poor connections. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0608: VSS OUTPUT CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied to Vehicle Speed Sensor (VSS) output circuit by various components which use VSS data. PCM creates VSS output signal by rapidly grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when the following conditions are present

1. Engine speed greater than 600 RPM.
2. Ignition voltage between 6-16 volts.
3. PCM detects commanded state of driver and actual state do not match.
4. Conditions met for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition off. Raise and support drive wheels. Start engine. Disable ASR/TCS systems (if equipped). Place gear selector into gear. If speedometer indicates any speed, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If speedometer does not indicate any speed, go to next step.
3. Install Signal Generator Tester (J-33431-B) between ground and PCM harness connector, VSS output circuit. Turn ignition on. Turn tester on and set to generate a vehicle speed signal. If speedometer indicates any speed, go to next step. If speedometer does not indicate any vehicle speed, check and repair circuits and connectors between PCM, electronic suspension control module (if equipped) and instrument cluster. If circuits and connections are okay, replace instrument cluster.
4. Check for poor connections/terminal tension at PCM connector. Repair as necessary. After repairs, go to step 6 . If connection or terminal tension is okay, go to next step.
5. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

The PCM output "L" terminal to alternator determines when generator will be turned off. It is on under all normal vehicle operating conditions except during low RPM conditions. Generator is turned off during low RPM conditions to remove excess load from engine. The generator warning light will illuminate anytime ignition is on and engine is not running. The warning light will turn off after engine is running and generator is putting out the desired amperage. DTC will set when engine is running, generator warning light is on, and generator "L" terminal voltage is low while PCM is commanding the generator on and condition is present for more than 30 seconds.

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) . After performing OBD system check, go to next step.
2. Start and operate engine at idle. Using scan tool, monitor generator. If scan tool indicates that generator is on, go to step 4 . If scan tool does not indicate that generator is on, go to next step.
3. Turn ignition off. Disconnect generator harness connector. Connect a DVOM between generator "L" terminal and a known-good ground. Start engine. Using scan tool, command generator on. Monitor voltage reading on DVOM. If voltage reading changes from zero to 5 volts, diagnose charging system. See appropriate STARTING & CHARGING SYSTEMS article. If voltage reading does not change from zero to 5 volts, go to next step.
4. Check generator "L" circuit for open or short to ground. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
5. Check generator "L" circuit for short to voltage. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to next step.
6. Check for poor connection at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
7. Replace PCM. program replacement PCM using required equipment. After replacing PCM, go to next step.
8. Using scan tool, review and record scan tool FAIL RECORDS data. Clear DTCs. Operate vehicle within conditions for setting this DTC. Recheck DTCs. If this DTC resets, go to step 2 . If this DTC does not reset, system is okay.

Check for faulty connections or damaged harness. Observe on scan tool display while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

DTC P0645: A/C CLUTCH RELAY CONTROL CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

A/C clutch relay control circuit is controlled by an internal switch (driver) inside PCM. Driver incorporates a fault line that is monitored by PCM. When PCM commands relay on, voltage on control circuit is low (near zero volts). With relay commanded off, control circuit voltage reaches near battery voltage. If fault detection circuit senses a voltage other than what the expected voltage should be, DTC P0645 will set.

For duplication of DTC, ensure engine speed is greater than 400 RPM, and ignition voltage is 6-18 volts.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command relay on and off. If relay responds as commanded, go to next step. If relay does not respond as commanded, go to step 5 .
3. Turn ignition off. Disconnect PCM harness connector C2. Turn ignition on. Using DVOM set on 10-amp scale, measure current between ground and relay control circuit at PCM harness connector for 2 minutes. If current draw is less than 0.75 amp, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If current draw is not less than 0.75 amp, go to next step.
4. Turn ignition off. Disconnect relay. Measure resistance between ground and relay control circuit at PCM harness connector. If resistance is infinite, go to step 12 . If resistance is not infinite, go to step 10 .
5. Turn ignition off. Disconnect relay. Connect test light between relay control circuit and relay ignition feed circuit at underhood electrical center. Turn ignition on, with engine off. Using scan tool, command relay on and off. If test light turns on and off with each command, go to step 8 . If test light does not turn on and off with each command, go to next step.
6. Using a test light connected to ground, probe relay ignition feed circuits at underhood electrical center. If test light illuminates for each circuit, go to next step. If test light does not illuminate for each circuit, go to step 11 .
7. Turn ignition off. Reconnect relay. Disconnect PCM harness connector C2. Turn ignition on. Connect a fused jumper wire between ground and relay control circuit at PCM harness connector. If relay operates, go to step 9 . If relay does not operate, go to step 10 .
8. Check for faulty relay connections. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 12 .
9. Check for faulty PCM harness connections. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to step 13 .
10. Repair faulty relay control circuit. After repairs, go to step 14 .
11. Repair faulty relay ignition feed circuit. After repairs, go to step 14 .
12. Replace relay. After repairs, go to step 14 .
13. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
14. Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step 2 .
15. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no undiagnosed DTCs are displayed, system is okay.

If ignition feed circuit is suspected of being open, check if other bulbs on this circuit illuminate. Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0650: MIL CONTROL CIRCUIT (3.0L "V" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied directly to Malfunction Indicator Light (MIL). ECM controls MIL signal by grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by ECM.

When ECM is commanding a component ON, voltage of control circuit should be low (near zero volts). When ECM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when ECM detects an open or short to ground in MIL circuit. For duplication of DTC, engine must be running, and battery voltage must be 7.5-14 volts.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. If MIL illuminates, go to step 6 . If MIL does not illuminate, go to next step.
3. Check fuse for instrument cluster ignition feed circuit. If fuse is okay, go to next step. If fuse is open, go to step 9 .
4. Turn ignition off. Disconnect ECM harness connectors. Turn ignition on. Using a fused jumper wire, jumper MIL control circuit at ECM harness connector to ground. If MIL illuminates, go to step 10 . If MIL does not illuminate, go to next step.
5. Check for faulty MIL bulb, open ignition feed circuit to MIL bulb, or open or short to battery voltage in MIL control circuit. Repair as necessary. After repairs, go to step 12 .
6. Using scan tool, check for DTCs. If any DTCs are set, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. If no DTCs are set, go to next step.
7. Turn ignition off. Disconnect ECM harness connectors. Turn ignition on, with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 11 .
8. Repair short to ground in MIL control circuit. After repairs, go to step 12 .
9. Repair short to ground in ignition feed circuit to instrument panel indicator lights. After repairs, go to step 12 .
10. Check for faulty ECM harness connections. Repair as necessary. After repairs, go to step 12 . If connections are okay, go to next step.
11. Replace ECM. Program replacement ECM using required equipment. Ensure ECM is programed with theft deterrent system frequency code currently on vehicle. After repairs, go to next step.
12. Start engine and observe MIL. If MIL illuminates briefly, and then turns off, system is okay. If MIL illuminates and remains on, perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article.

If ignition feed circuit is suspected of being open, check if other bulbs on this circuit illuminate. Check for open fuses in fuse block. Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0650: MIL CONTROL CIRCUIT (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied directly to Malfunction Indicator Light (MIL). PCM controls MIL signal by grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when PCM detects that the commanded state of the driver and the actual state of the control circuit do not match and condition is present for a minimum of 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If MIL does not turn on or off when commanded, go to next step.
3. Turn ignition off. Disconnect PCM harness connector containing MIL control circuit. Turn ignition on. If MIL is off, go to next step. If MIL is on, go to step 5 .
4. Connect a fused jumper wire between ground and MIL control circuit at PCM connector (harness side). If MIL is on, go to step 6 . If MIL is not on, go to step 7 .
5. Repair short to ground in MIL control circuit. After repairs, go to step 9 .
6. Check connections at PCM. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to step 8 .
7. Check for faulty MIL bulb, open ignition feed circuit to bulb, or MIL control circuit open or shorted to battery voltage. Repair as necessary. After repairs, go to step 9 .
8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If ignition feed circuit is suspected of being open, check if other bulbs on this circuit illuminate. Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0650: MIL CONTROL CIRCUIT (5.7L "F" & "Y" BODIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied directly to Malfunction Indicator Light (MIL). PCM controls MIL signal by grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when the following conditions are present

1. Engine speed greater than 600 RPM.
2. Ignition voltage between 6-16 volts.
3. PCM detects commanded state of driver and actual state do not match.
4. Conditions met for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command MIL on and off. If MIL turns on and off as commanded, see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If MIL does not turn on or off when commanded, go to next step.
3. Turn ignition off. Disconnect PCM harness connector containing MIL control circuit. Turn ignition on. If MIL is off, go to next step. If MIL is on, go to step 5 .
4. Connect a fused jumper wire between ground and MIL control circuit at PCM connector (harness side). If MIL is on, go to step 6 . If MIL is not on, go to step 7 .
5. Repair short to ground in MIL control circuit. After repairs, go to step 9 .
6. Check connections at PCM. Repair as necessary. After repairs, go to step 9 . If connections are okay, go to step 8 .
7. Check for faulty MIL bulb, open ignition feed circuit to bulb, or MIL control circuit open or shorted to battery voltage. Repair as necessary. After repairs, go to step 9 .
8. Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
9. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
10. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If ignition feed circuit is suspected of being open, check if other bulbs on this circuit illuminate. Using FREEZE FRAME and/or FAILURE RECORD data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0654: ENGINE SPEED OUTPUT CIRCUIT (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied directly to engine speed output circuit. PCM creates engine speed output signal by rapidly grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

DTC will set when PCM detects that the commanded state of the driver and the actual state of the control circuit do not match and condition is present for a minimum of 5 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. Ensure instrument panel is operating properly. Repair instrument panel before proceeding with test. Start engine. Monitor vehicle tachometer, If tachometer indicates engine speed (RPM), see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If tachometer does not indicate engine speed, go to next step.
3. Turn ignition off. Remove underhood electrical center cover and side shield. Lift underhood electrical center to gain access to 16-pin harness connector. Disconnect 16-pin harness connector. Turn ignition on. Check engine speed output voltage between ground and engine speed output circuit voltage and female side of connector. If voltage reading is greater than 9.5 volts, go to step 6 . If voltage reading is not greater than 9.5 volts, go to next step.
4. Turn ignition off. Remove instrument panel. Check continuity between engine speed output control at Instrument Control Panel (IPC) harness connector to PCM harness connector. If continuity exists, go to next step. If continuity does not exist, go to step 8 .
5. Check continuity between engine speed circuit and battery ground. If continuity exists, go to step 9 . If continuity does not exist, diagnose IPC.
6. Turn ignition off. Disconnect PCM harness connector C2. Check continuity of engine speed output control circuit between PCM and IPC harness connector. If continuity exists, go to next step. If continuity does not exist, go to step 10 .
7. Check continuity between ground and engine speed output circuit. If continuity exists, go to step 11 . If continuity does not exist, go to step 12 .
8. Repair open in engine speed output circuit from IPC to splice connector. After repairs, go to step 14 .
9. Repair grounded engine speed output circuit from IPC to splice connector. After repairs, go to step 14 .
10. Repair open in engine speed output circuit from PCM to splice connector. After repairs, go to step 14 .
11. Repair grounded engine speed output circuit from PCM to splice connector. After repairs, go to step 14 .
12. Check for poor connections at PCM harness connector and splice connector. Repair as necessary. After repairs, go to step 14 . If connections are okay, go to next step.
13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
15. Using scan tool, select CAPTURE INFO and REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0654: ENGINE SPEED OUTPUT CIRCUIT (5.7L "Y" BODY)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

Voltage is supplied directly to engine speed output circuit. PCM creates engine speed output signal by rapidly grounding this circuit through an internal switch called a driver. Primary function of driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM.

When PCM is commanding a component ON, voltage of control circuit should be low (near zero volts). When PCM is commanding control circuit to a component OFF, voltage potential of circuit should be high (near battery voltage). If fault detection circuit senses a voltage other than what is expected, fault line status will change, causing DTC to set.

Conditions for setting DTC

1. Engine speed greater than 600 RPM.
2. Ignition voltage between 6-16 volts.
3. PCM detects commanded state of driver and actual state do not match.
4. Conditions met for 10 seconds.

1. Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-132811-S27457185922002013000000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
2. With engine running, if vehicle tachometer indicates engine speed (RPM), see «DIAGNOSTIC AIDS»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) . If no engine RPM is indicated, go to next step.
3. Turn ignition off. Disconnect PCM harness connector. Install Signal Generator Tester (J-33431-B) between ground and PCM harness connector, engine speed output circuit. Turn ignition on. Turn tester on and set to generate a vehicle speed signal. If tachometer indicates any RPM, go to next step. If tachometer does not indicate any RPM, check and repair circuits and connectors between PCM and instrument cluster. If circuits and connections are okay, replace instrument cluster.
4. Check for poor connections/terminal tension at PCM connector. Repair as necessary. After repairs, go to step 6 . If connection or terminal tension is okay, go to next step.
5. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
6. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2 .
7. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Using FREEZE FRAME and/or FAILURE RECORDS data mode may aid in locating an intermittent condition. If DTC cannot be duplicated, information included in FREEZE FRAME and/or FAILURE RECORDS data can be useful in determining how many miles since DTC set. FAIL COUNTER and PASS COUNTER can also be used to determine how many ignition cycles diagnostic reported a pass or a fail condition. To isolate when DTC failed, operate vehicle within same freeze frame conditions (RPM, load, vehicle speed, temperature, etc.).

DTC P0656: FUEL GAUGE CIRCUIT FAULT (1.9L SATURN)

Note. For circuit reference, see appropriate wiring diagram in WIRING DIAGRAMS article.

PCM monitors the resistance of fuel level sensor (tank sensor), calculates the amount of fuel in the tank, and provide a Pulse Width Modulated (PWM) ground to control the fuel gauge. The duty cycle increases to move gauge to FULL (86 percent) and decreases (15 percent) to command EMPTY. During the 3 second key-on bulb check, PCM commands the fuel gauge to zero percent duty cycle and activates the LOW FUEL light. The diagnostic test is performed only when the gauge is commanded to a zero percent duty cycle (e.g., during key-on bulb check period or if DTC P0462 or P0463 is set). DTC P0656 will set if the commanded duty cycle is zero and the output feedback is low (should be high/ignition voltage).

DTC P0656 will set if the commanded duty cycle is zero percent and output feedback is less than 3 volts for longer than one second. If output voltage is shorted to battery voltage, fuel gauge will be forced to zero percent duty cycle and the LOW FUEL light state (on/off) will depend on actual fuel level.

1. If complaint is fuel gauge not accurate, go to next step. If DTC P0656 is set, go to step 3 .
2. Install scan tool. Turn ignition on, with engine off. Using scan tool, command fuel gauge to E, 1/4, 1/2, 3/4 and F. If gauge reading is within appropriate range, verify fuel tank sensor resistance value. See «FUEL TANK SENSOR RESISTANCE»(/gmc/savana/i-1996-2002/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p0453-p0656) table. If scan tool reading is not within appropriate range, check instrument cluster for faulty fuel gauge.
3. Check if DTC P0656 is active or history DTC. If DTC is history, problem is intermittent. If DTC is active, go to next step.
4. Turn ignition on. Observe status of fuel gauge feedback. If feedback status does not stay high, go to next step. If feedback status is high, disconnect 18-way cluster connector. If feedback status stays high, check for short to voltage in fuel gauge circuit to PCM. If circuit is okay, replace PCM. If feedback status does not stay high, diagnose instrument cluster.
5. Turn ignition off. Disconnect PCM harness connector J1. Turn ignition on. Using a DVOM connected to ground, backprobe circuit No. 455 to fuel gauge. If ignition voltage is not present, go to next step. If ignition voltage is present, check for terminal tightness at PCM. If terminals are okay, replace PCM.
6. Turn ignition off. Reconnect PCM harness connector. Disconnect Natural color harness connector from instrument cluster. Using a fused jumper wire, jumper, jumper harness connector terminals to circuits No. 39 and 455. If fuel gauge status is high, diagnose instrument cluster. If fuel gauge status is not high, check or repair for open or short to ground in circuit No. 455. If circuit is okay, check for terminal tightness to PCM. If terminals are okay, replace PCM.

FUEL TANK SENSOR RESISTANCE

See also:
• DIAGNOSTIC AIDS
• DIAGNOSTIC AIDS