Engine Control System - Tests W/codes - DTC p1273-p1536 — Cadillac DeVille Concours I final (1999-1999)

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 P1273: APP SENSORS NO. 1 & 3 CORRELATION ERROR (3.8L "F" BODY)

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

Circuit Description

The Accelerator Pedal Position (APP) sensors are mounted on accelerator pedal/TAC module assembly. The are 3 individual APP sensors within one housing and 3 separate signal, ground and reference circuits are used which are contained with the Throttle Actuator Control (TAC) module. The APP sensor signal voltage increases as accelerator pedal is depressed. The signal circuits pull to ground within the TAC module.

DTC will set when APP sensor No. 2 disagrees with APP sensor No. 3 by greater than 10.5 percent or the APP No. 2 signal is shorted to the APP No. 3 signal and all these conditions are present for less than one second.

Diagnostic Procedures

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if other DTCs are also set. If other DTCs are also set, diagnose affected DTCs first. If no other DTCs are set, go to next step.
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Diagnostic Aids

Check for poor connections, corrosion, misrouted harness, rubbed-through wire insulation or broken wire inside insulation. When TAC module detects a problem within the ETC system and PCM receives a message across the serial data and more than one ETC system related DTC may set due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC.

DTC P1275: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (3.0L "V" BODY)

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

This DTC will run when battery voltage is greater than 7 volts. DTC will set when voltage for Accelerator Pedal Position (APP) sensor No. 1 is greater than 4.4 volts or less than 0.23 volt, or the rationality of TP sensor No. 2 is greater than 0.2 volt in part load/throttle or greater than 1.13 volts in full throttle. ECM will illuminate MIL and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and does not fail. A history DTC clears after 40 consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect ECM harness connector. Using a test light connected to battery voltage, probe APP sensor ground circuit at ECM harness connector. If test light illuminates, go to step 6 . If test light does not illuminate, go to next step.
Connect test light to ground. Probe test light to APP signal circuit and 5-volt reference circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
Disconnect APP sensor harness connector. Check resistance of ground circuit, signal circuit and 5-volt reference circuit. If resistance is infinite, go to step 7 . If resistance is not infinite, go to next step.
Replace APP sensor. After replacing sensor, go to step 8 .
Repair short to ground in circuit that caused test light to illuminate. After repairs, go to step 8 .
Repair open in circuit. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1275: APP SENSOR NO. 1 CIRCUIT (3.8L "F" BODY)

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

DTC will set when APP sensor No. 1 voltage is less than 0.68 volt or greater than 4.5 volts and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Ensure foot is off the accelerator pedal. Turn on, with engine off. Using scan tool in TAC DATA LIST, monitor APP sensor No. 1 voltage. If voltage reading is 0.7-1.1 volts, go to next step. If voltage reading is not 0.7-1.1 volts, go to step 5 .
Fully depress accelerator pedal. If voltage reading is 2.7-4.2 volts, go to next step. If voltage reading is not 2.7-4.2 volts, go to step 5 .
Using scan tool, select FAILED THIS IGNITION option. Depress accelerator pedal to Wide Open Throttle (WOT), then release to fully closed position. If this DTC sets, go to next step. If this DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1275: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The Accelerator Pedal Position (PAP) sensor is mounted on accelerator pedal assembly. Sensor contains 3 individual APP sensors within one housing. There are 3 separate signal, ground and 5-volt reference circuits connected to APP and Throttle Actuator Control (TAC) modules. Each sensor has a unique functionality

The APP sensor No. 1 signal increases as accelerator pedal is depressed from less than 1.1 volt (zero percent with pedal at rest) to greater than 2.1 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 3.9 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.2 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Ensure accelerator pedal is not depressed. Using scan tool, select TAC DATA LIST option. Monitor APP sensor No. 1 voltage. If voltage reading is 0.25-2.24 volts, go to next step. If voltage reading is not 0.25-2.24 volts, go to step 6 .
Fully depress accelerator pedal. Check voltage reading on scan tool. If voltage reading is 2.24-4.23 volts, go to next step. If voltage reading is not 2.24-4.23 volts, go to step 6 .
Turn ignition off for 15 seconds. Turn ignition on, engine off. Using scan tool, select DTC option and FAILED THIS IGNITION option. Move/wiggle harness connectors and related connectors. If this DTC sets, go to step 29 . If this DTC does not set, go to next step.
Depress accelerator pedal to Wide Open Throttle (WOT) position then return to closed position. If this DTC sets, go to step 25 . If this DTC does not set, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect APP sensor harness connector. If scan tool reads zero volts, go to next step. If scan tool does not read zero volts, go to step 11 .
Using a test light connected to battery voltage, probe APP sensor No. 1 signal circuit. If scan tool reads 5 volts, go to next step. If scan tool does not read 5 volts, go to step 13 .
Check voltage between APP sensor No. 1 5-volt reference circuit and battery ground. If voltage reading is 4.6-5.4 volts, go to step 10 . If voltage reading is not 4.6-5.4 volts, go to next step.
Turn ignition off. Disconnect throttle actuator motor connector. Remove air inlet duct from throttle body. Turn ignition on, with engine off. Rotate throttle blade by hand to wide open throttle. Hold throttle blade in this position. Check voltage between APP sensor No. 1 5-volt reference circuit at harness connector and battery ground. If voltage reading is 4.6-5.4 volts, go to step 26 . If voltage reading is not 4.6-5.4 volts, go to step 16 .
Check resistance between APP sensor No. 1 ground circuit and battery ground. If resistance is 0-5 ohms, go to step 24 . If resistance is not 0-5 ohms, go to step 17 .
Turn ignition off. Leave APP sensor disconnected. Disconnect TAC module connector containing the APP sensor circuits. Turn ignition on, with engine off. Check voltage between battery ground and APP sensor No. 1 signal circuit in APP sensor harness connector. If voltage reading is zero volts, go to next step. If voltage reading is not zero volts, go to step 18 .
Turn ignition off. Disconnect the other TAC module connector. Check continuity between APP sensor No. 1 signal circuit and all other circuits in both TAC module connectors. If continuity exists, go to step 19 . If continuity does not exist, go to step 28 .
Turn ignition off. Disconnect TAC module connector containing the APP sensor circuits. Check continuity of APP sensor No. 1 signal circuit. If continuity exists, go to next step. If continuity does not exist, go to step 20 .
Check continuity between APP sensor No. 1 signal circuit and battery ground. If continuity exists, go to step 21 . If continuity does not exist, go to next step.
Turn ignition off. Disconnect the other TAC harness connector. Check continuity between APP sensor No. 1 signal circuit and all other circuits in both TAC module connectors. If continuity exists, go to step 19 . If continuity does not exist, go to step 27 .
Turn ignition off. Leave APP sensor harness connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Check continuity of APP sensor No. 1 5-volt reference circuit. If continuity exists, go to step 27 . If continuity does not exist, go to step 22 .
Turn ignition off. Leave APP sensor harness connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Check continuity of APP sensor No. 1 ground circuit. If continuity exists, go to step 27 . If continuity does not exist, go to step 23 .
Repair signal circuit for short to voltage. After repairs, go to step 30 .
Repair short between APP sensor signal circuit and TAC circuit that had continuity. After repairs, go to step 30 .
Repair open or high resistance in signal circuit. After repairs, go to step 30 .
Repair short to ground in signal circuit. After repairs, go to step 30 .
Repair open or high resistance in 5-volt reference circuit. After repairs, go to step 30 .
Repair open or high resistance in ground circuit. After repairs, go to step 30 .
Check for poor connection or terminal tension at APP sensor harness connector. Repair as necessary. After repairs, go to step 30 . If connection or terminal tension is okay, go to next step.
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 30 .
If DTC P1120 was set when performing step 9 , diagnose using DTC P1120 test. If DTC P1120 was not set, go to next step.
Check for poor connection or terminal tension at TAC module harness connector. Repair as necessary. After repairs, go to step 30 . If connector or terminal tension is okay, go to next step.
Replace TAC module. After replacing module, go to next step.
Repair harness connectors as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

Check for poor connections, corrosion, misrouted harness, rubbed-through wire insulation or broken wire inside insulation. The APP and TP sensor 5-volt reference circuit are internally connected within the TAC. Check the 5-volt reference circuits at the APP and TP sensors for an open, short to ground or short to voltage. DTC P1276 will also set when TAC module detects throttle movement when DTC P1275 is set.

DTC P1276: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (3.8L "F" BODY)

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

DTC will set when APP sensor No. 1 disagrees with APP sensor No. 2 by greater than 10.5 percent and APP sensor No. 1 disagrees with APP sensor No. 3 by greater than 10.5 percent and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool in TAC DATA LIST option, monitor APP sensor No. 1 voltage. If voltage reading is 0.5-1.3 volts, go to next step. If voltage reading is not 0.5-1.3 volts, go to step 4 .
Using scan tool, monitor APP sensors No. 1 and 2, and APP sensors No. 1 and 3 disagree parameter. Slowly depress accelerator pedal to Wide Open Throttle (WOT) position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at 75, 50 and 25 percent positions. If scan tool displays NO for the APP sensors No. 1 and 2 disagree, and APP sensors No. 1 and 3 disagree parameters, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not display NO, go to next step.
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1276: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The Accelerator Pedal Position (APP) sensor is mounted on accelerator pedal assembly. Sensor contains 3 individual APP sensors within one housing. There are 3 separate signal, ground and 5-volt reference circuits connected to APP and Throttle Actuator Control (TAC) modules. Each sensor has a unique functionality

The APP sensor No. 1 signal increases as accelerator pedal is depressed, from less than one volt (zero percent with pedal at rest) to greater than 2.0 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 4.0 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.8 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Observe that signal circuits for APP sensor No. 2 and APP sensor No. 3 pull up to 5 volts and APP sensor No. 1 circuit pull to ground within the TAC module. DTC will set when APP sensor No. 1 disagrees with APP sensor No. 2 by greater than 10.5 percent and APP sensor No. 1 disagrees with APP sensor No. 3 by greater than 13 percent and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P1518 is also set. If DTC P1518 is set, diagnose DTC first. If DTC P1518 is not set, go to next step.
DO NOT depress accelerator pedal. Start and operate engine at idle. Using scan tool, monitor DTC information. If any other TAC module or APP sensor DTCs set (except P1125), go to applicable DTC test. If no other DTCs are set, go to next step.
Using scan tool, monitor APP SENSOR DISAGREE parameter. If scan tool displays YES for any of the parameters, go to step 6 . If scan tool does not display YES for any of the parameters, go to next step.
Using scan tool, monitor angle of APP sensors No. 1, 2 and 3. Slowly depress accelerator pedal to WOT position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at about 75, 50 and 25 percent positions. If APP sensor No. 1 angle corresponds to APP sensors No. 2 and 3 angles, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If APP sensor No. 1 angle does not correspond to APP sensors No. 2 and 3, go to next step.
Turn ignition off. Disconnect APP sensor harness connector. Using a jumper wire, jumper APP sensor No. 1 5-volt reference circuit to a known-good ground. Turn ignition on, with engine off. Using scan tool, monitor TP sensor No. 1 voltage. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 11 .
Jumper APP sensor No. 1 5-volt reference circuit to APP sensor No. 1 ground circuit. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 12 .
Jumper APP sensor No. 1 signal circuit to APP sensor No. 1 5-volt reference circuit. If scan tool displays 5 volts, go to step 14 . If scan tool does not display 5 volts, go to next step.
Leave ignition on. Check resistance between APP sensor No. 1 signal circuit to all other circuit in APP sensor connectors. If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step 13 .
Turn ignition off. Disconnect both TAC module harness connectors. Check continuity between APP sensor No. 1 signal circuit to all other circuits at both TAC module harness connectors. If continuity exists, go to step 17 . If continuity does not exist, go to step 15 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 1 5-volt reference circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 1 ground circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 1 signal circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Check for poor connections at APP harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 18 .
Check for poor connections at TAC module harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 19 .
Repair open or excessive resistance in affected circuit. After repairs, go to step 20 .
Repair shorted circuits that displayed continuity. After repairs are complete, go to step 20 .
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 20 .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1280: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (3.0L "V" BODY)

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

This DTC will run when battery voltage is greater than 7 volts. DTC will set when TP sensor No. 1 voltage is greater than 4.9 volts or less than 0.12 volt, or the rationality of TP sensor No. 1 is greater than 0.2 volt in part load/throttle or greater than 1.13 volts in full throttle. ECM will illuminate MIL and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect ECM harness connector. Using a test light connected to battery voltage, probe APP sensor ground circuit at ECM harness connector. If test light illuminates, go to step 6 . If test light does not illuminate, go to next step.
Connect test light to ground. Probe test light to APP signal circuit and 5-volt reference circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
Disconnect APP sensor harness connector. Check resistance of ground circuit, signal circuit and 5-volt reference circuit. If resistance is infinite, go to step 7 . If resistance is not infinite, go to next step.
Replace APP sensor. After replacing sensor, go to step 8 .
Repair short to ground in circuit that caused test light to illuminate. After repairs, go to step 8 .
Repair open in circuit. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1280: APP SENSOR NO. 2 CIRCUIT (3.8L "F" BODY)

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

DTC will set when APP sensor No. 2 voltage is less than 0.68 volt or greater than 4.5 volts and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Ensure foot is off the accelerator pedal. Turn on, with engine off. Using scan tool in TAC DATA LIST, monitor APP sensor No. 2 voltage. If voltage reading is 0.5-1.3 volts, go to next step. If voltage reading is not 0.5-1.3 volts, go to step 5 .
Fully depress accelerator pedal. If voltage reading is 2.9-4.0 volts, go to next step. If voltage reading is not 2.9-4.0 volts, go to step 5 .
Using scan tool, select FAILED THIS IGNITION option. Depress accelerator pedal to Wide Open Throttle (WOT), then release to fully closed position. If this DTC sets, go to next step. If this DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1280: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The APP sensor No. 1 signal increases as accelerator pedal is depressed from less than 1.1 volt (zero percent with pedal at rest) to greater than 2.1 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 3.9 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.2 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Observe that signal circuits for APP sensor No. 2 and APP sensor No. 3 pull up to 5 volts and APP sensor No. 1 circuit pull to ground within the TAC module. DTC will set when APP sensor No. 2 voltage ranges between 0.83 volt and 4.81 volts and condition is met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Ensure accelerator pedal is not depressed. Using scan tool in TAC DATA LIST option, monitor APP sensor No. 2 voltage. If voltage reading is 3.90-4.81 volts, go to next step. If voltage reading is not 3.90-4.81 volts, go to step 6 .
Fully depress accelerator pedal. Check voltage reading on scan tool. If voltage reading is 0.83-2.90 volts, go to next step. If voltage reading is not 0.83-2.90 volts, go to step 6 .
Turn ignition off for 15 seconds. Turn ignition on, engine off. Using scan tool, select DTC option and FAILED THIS IGNITION option. Move/wiggle harness connectors and related connectors. If this DTC sets, go to step 21 . If this DTC does not set, go to next step.
Slowly depress accelerator pedal to Wide Open Throttle (WOT) position then return to closed position. If this DTC sets, go to step 31 . If this DTC does not set, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect APP sensor harness connector. Check voltage between battery ground and APP sensor No. 2 signal circuit at APP sensor harness connector. If voltage reading is 3.94-6.06 volts, go to step 11 . If voltage reading is not 3.94-6.06 volts, go to next step.
Turn ignition off. Leave APP sensor connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Turn ignition on, engine off. Check voltage between APP sensor No. 2 harness connector signal circuit and battery ground. If any voltage is present, go to step 25 . If no voltage is present, go to next step.
Check continuity in APP sensor No. 2 signal circuit. If continuity exists, go to next step. If continuity does not exist, go to step 26 .
Check harness for continuity between APP sensor No. 2 signal circuit and battery ground. If continuity exists, go to step 27 . If continuity does not exist, go to next step.
Check for continuity between APP sensor No. 2 signal circuit and TAC harness connector. Check all other circuits in both TAC module harness connector. If continuity exists, go to step 29 . If continuity does not exist, go to step 32 .
Check voltage between battery ground and APP sensor No. 2 harness connector 5-volt reference circuit. If voltage reading is 3.94-6.06 volts, go to step 16 . If voltage reading is not 3.94-6.06 volts, go to next step.
Turn ignition off. Disconnect TAC harness connector containing APP sensor circuits. Turn ignition on, engine off. Check voltage between battery ground and APP sensor No. 2 5-volt reference circuit at harness connector. If any voltage is present, go to step 22 . If no voltage is present, go to next step.
Check for continuity in harness between APP sensor No. 2 5-volt reference circuit and sensor ground. If continuity exists, go to next step. If continuity does not exist, go to step 23 .
Check for continuity in harness between APP sensor No. 2 5-volt reference circuit battery ground. If continuity exists, go to step 24 . If continuity does not exist, go to next step.
Check harness for continuity between APP sensor No. 2 5-volt reference circuit at TAC harness connector and all the other circuit in both TAC connectors. If continuity exists, go to step 29 . If continuity does not exist, go to step 32 .
Check resistance between battery ground and APP sensor No. 2 ground circuit at APP sensor harness connector. If measured resistance is 0-5 ohms, go to step 18 . If resistance is not 0-5 ohms, go to next step.
Turn ignition off. Leave APP sensor harness connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Check continuity of APP sensor No. 2 ground circuit. If continuity exists, go to step 32 . If continuity does not exist, go to step 28 .
Using a fused jumper wire, jumper APP sensor No. 2 signal circuit to APP sensor ground circuit in harness connector. Using scan tool, monitor APP sensor No. 2 voltage. If scan tool indicates zero volts, go to next step. If scan tool does not indicate zero volts, go to step 33 .
Using a fused jumper wire, jumper APP sensor No. 2 signal circuit and APP sensor ground circuit. Using scan tool monitor, APP sensors No. 1 and 3 and TP sensor No. 2 voltage. If any of the sensor voltage is affected when APP sensor No. 2 signal is grounded, go to next step. If sensor voltage is not affected, go to step 30 .
Turn ignition off. Disconnect TAC harness connector. Check continuity between APP sensor No. 2 signal circuit at TAC harness connector, and all other circuits in both TAC module connectors. If continuity exists, go to step 29 . If continuity does not exist, go to step 33 .
Repair harness/connections as necessary. After repairs, go to step 34 .
Repair short to voltage in 5-volt reference circuit. After repairs, go to step 34 .
Repair open or high resistance in 5-volt reference circuit. After repairs, go to step 34 .
Repair short to ground in 5-volt reference circuit. After repairs, go to step 34 .
Repair signal circuit for short to voltage. After repairs, go to step 34 .
Repair open or high resistance in signal circuit. After repairs, go to step 34 .
Repair short to ground in signal circuit. After repairs, go to step 34 .
Repair open or high resistance in ground circuit. After repairs, go to step 34 .
Repair circuits that are shorted together. After repairs, go to step 34 .
Check for poor connection at APP sensor harness connector. Repair as necessary. After repairs, go to step 34 . If connection is okay, go to next step.
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 34 .
Check for poor connection at TAC module harness connector. Repair as necessary. After repairs, go to step 34 . If connector is okay, go to next step.
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1281: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (3.8L "F" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool in TAC DATA LIST option, monitor APP sensor No. 1 voltage. If voltage reading is 0.5-1.3 volts, go to next step. If voltage reading is not 0.5-1.3 volts, go to step 4 .
Using scan tool, monitor APP sensors No. 1 and 2, and APP sensors No. 1 and 3 disagree parameter. Slowly depress accelerator pedal to Wide Open Throttle (WOT) position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at 75, 50 and 25 percent positions. If scan tool displays NO for the APP sensors No. 1 and 2 disagree, and APP sensors No. 2 and 3 disagree parameters, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not display NO, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool in DTC and FAILED THIS IGNITION option, quickly depress accelerator pedal to WOT and then quickly release/return pedal to closed throttle position. If this DTC sets, go to next step. If this DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1281: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The APP sensor No. 1 signal increases as accelerator pedal is depressed, from less than 1.1 volt (zero percent with pedal at rest) to greater than 2.1 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 3.9 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.2 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Observe that signal circuits for APP sensor No. 2 and APP sensor No. 3 pull up to 5 volts and APP sensor No. 1 circuit pull to ground within the TAC module. DTC will set when APP sensor No. 2 disagrees with APP sensor No. 1 by greater than 10.5 percent and APP sensor No. 2 disagrees with APP sensor No. 3 by greater than 13 percent and conditions is met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P1518 is also set. If DTC P1518 is set, diagnose DTC first. If DTC P1518 is not set, go to next step.
DO NOT depress accelerator pedal. Start and operate engine at idle. Using scan tool, monitor DTC information. If any other TAC module or APP sensor DTCs set (except P1125), go to applicable DTC test. If no other DTCs are set, go to next step.
Using scan tool, monitor APP SENSOR DISAGREE parameter. If scan tool displays YES for any of the parameters, go to step 6 . If scan tool does not display YES for any of the parameters, go to next step.
Using scan tool, monitor angle of APP sensors No. 1, 2 and 3. Slowly depress accelerator pedal to WOT position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at about 75, 50 and 25 percent positions. If APP sensor No. 1 angle corresponds to APP sensors No. 2 and 3 angles, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If APP sensor No. 1 angle does not correspond to APP sensors No. 2 and 3, go to next step.
Turn ignition off. Disconnect APP sensor harness connector. Using a jumper wire, jumper APP sensor No. 2 5-volt reference circuit to a known-good ground. Turn ignition on, with engine off. Using scan tool, monitor TP sensor No. 2 voltage. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 11 .
Jumper APP sensor No. 2 5-volt reference circuit to APP sensor No. 2 ground circuit. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 12 .
Jumper APP sensor No. 2 signal circuit to APP sensor No. 2 5-volt reference circuit. If scan tool displays 5 volts, go to step 14 . If scan tool does not display 5 volts, go to next step.
Leave ignition on. Check resistance between APP sensor No. 2 signal circuit to all other circuit in APP sensor connectors. If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step 13 .
Turn ignition off. Disconnect both TAC module harness connectors. Check continuity between APP sensor No. 2 signal circuit to all other circuits at both TAC module harness connectors. If continuity exists, go to step 17 . If continuity does not exist, go to step 15 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 2 5-volt reference circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 2 ground circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 2 signal circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Check for poor connections at APP harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 18 .
Check for poor connections at TAC module harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 19 .
Repair open or excessive resistance in affected circuit. After repairs, go to step 20 .
Repair shorted circuits that displayed continuity. After repairs are complete, go to step 20 .
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 20 .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1285: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (3.8L "F" BODY)

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

DTC will set when APP sensor No. 3 voltage is less than 0.68 volt or greater than 4.5 volts and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Ensure foot is off the accelerator pedal. Turn on, with engine off. Using scan tool in TAC DATA LIST, monitor APP sensor No. 2 voltage. If voltage reading is 0.5-1.3 volts, go to next step. If voltage reading is not 0.5-1.3 volts, go to step 5 .
Fully depress accelerator pedal. If voltage reading is 2.9-4.0 volts, go to next step. If voltage reading is not 2.9-4.0 volts, go to step 5 .
Using scan tool, select FAILED THIS IGNITION option. Depress accelerator pedal to Wide Open Throttle (WOT), then release to fully closed position. If this DTC sets, go to next step. If this DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1285: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The APP sensor No. 1 signal increases as accelerator pedal is depressed from less than 1.1 volt (zero percent with pedal at rest) to greater than 2.1 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 3.9 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.2 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Observe that signal circuits for APP sensor No. 2 and APP sensor No. 3 pull up to 5 volts and APP sensor No. 1 circuit pull to ground within the TAC module. DTC will set when APP sensor No. 3 voltage is less than 1.63 volts or greater than 4.28 volts and condition met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Using scan tool, monitor APP sensor No. 3 voltage. If voltage reading is 3.29-4.28 volts, go to next step. If voltage reading is not 3.29-4.28 volts, go to step 6 .
Fully depress accelerator pedal. Check voltage reading on scan tool. If voltage reading is 1.63-3.10 volts, go to next step. If voltage reading is not 1.63-3.10 volts, go to step 6 .
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool, select DTC option. Move/wiggle harness connectors and related connectors. If this DTC sets, go to step 19 . If this DTC does not set, go to next step.
Slowly depress accelerator pedal to Wide Open Throttle (WOT) position then slowly return to closed position. If this DTC sets, go to step 29 . If this DTC does not set, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect APP sensor harness connector. Check voltage between battery ground and APP sensor No. 3 signal circuit at APP sensor harness connector. If voltage reading is 3.94-6.06 volts, go to step 11 . If voltage reading is not 3.94-6.06 volts, go to next step.
Turn ignition off. Leave APP sensor connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Turn ignition on, engine off. Check voltage between APP sensor No. 3 harness connector signal circuit and battery ground. If any voltage is present, go to step 23 . If no voltage is present, go to next step.
Check continuity in APP sensor No. 3 signal circuit. If continuity exists, go to next step. If continuity does not exist, go to step 24 .
Check harness for continuity between APP sensor No. 3 signal circuit and battery ground. If continuity exists, go to step 25 . If continuity does not exist, go to next step.
Check for continuity between APP sensor No. 3 signal circuit at TAC harness connector and all other circuits in both TAC module harness connector. If continuity exists, go to step 27 . If continuity does not exist, go to step 30 .
Check voltage between battery ground and APP sensor No. 3 harness connector 5-volt reference circuit. If voltage reading is 3.94-6.06 volts, go to step 16 . If voltage reading is not 3.94-6.06 volts, go to next step.
Turn ignition off. Leave APP sensor harness connector connected. Disconnect TAC harness connector containing APP sensor circuits. Turn ignition on, engine off. Check voltage between battery ground and APP sensor No. 3 5-volt reference circuit at harness connector. If any voltage is present, go to step 20 . If no voltage is present, go to next step.
Check for continuity in harness between APP sensor No. 3 5-volt reference circuit and sensor ground. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Check for continuity in harness between APP sensor No. 3 5-volt reference circuit battery ground. If continuity exists, go to step 22 . If continuity does not exist, go to next step.
Check harness for continuity between APP sensor No. 3 5-volt reference circuit at TAC harness connector and all the other circuit in both TAC connectors. If continuity exists, go to step 27 . If continuity does not exist, go to step 30 .
Check resistance between battery ground and APP sensor No. 3 ground circuit at APP sensor harness connector. If resistance is 0-5 ohms, go to step 18 . If resistance is not 0-5 ohms, go to next step.
Turn ignition off. Leave APP sensor harness connector disconnected. Disconnect TAC module harness connector containing APP sensor circuit. Check continuity of APP sensor No. 3 ground circuit. If continuity exists, go to step 30 . If continuity does not exist, go to step 26 .
Turn ignition on, with engine off. Using a fused jumper wire, jumper APP sensor No. 3 signal circuit to APP sensor ground in APP harness connector. Using scan tool, monitor APP sensor No. 3 voltage. If scan tool indicates zero volts, go to step 28 . If scan tool does not indicate zero volts, go to step 30 .
Repair harness/connections as necessary. After repairs, go to step 32 .
Repair short to voltage in 5-volt reference circuit. After repairs, go to step 32 .
Repair open or high resistance in 5-volt reference circuit. After repairs, go to step 32 .
Repair short to ground in 5-volt reference circuit. After repairs, go to step 32 .
Repair signal circuit for short to voltage. After repairs, go to step 32 .
Repair open or high resistance in signal circuit. After repairs, go to step 32 .
Repair short to ground in signal circuit. After repairs, go to step 32 .
Repair open or high resistance in ground circuit. After repairs, go to step 32 .
Repair circuits that are shorted together. After repairs, go to step 32 .
Check for poor connection at APP sensor harness connector. Repair as necessary. After repairs, go to step 32 . If connection is okay, go to next step.
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 32 .
Check for poor connection at TAC module harness connector. Repair as necessary. After repairs, go to step 32 . If connector is okay, go to next step.
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1286: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (3.8L "F" BODY)

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

DTC will set when APP sensor No. 3 disagrees with APP sensor No. 1 by greater than 10.5 percent and APP sensor No. 3 disagrees with APP sensor No. 2 by greater than 10.5 percent and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool in TAC DATA LIST option, monitor APP sensor No. 1 voltage. If voltage reading is 0.5-1.3 volts, go to next step. If voltage reading is not 0.5-1.3 volts, go to step 4 .
Using scan tool, monitor APP sensors No. 1 and 2, and APP sensors No. 1 and 3 disagree parameter. Slowly depress accelerator pedal to Wide Open Throttle (WOT) position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at 75, 50 and 25 percent positions. If scan tool displays NO for the APP sensors No. 1 and 2 disagree, and APP sensors No. 2 and 3 disagree parameters, go to next step. If scan tool does not display NO, go to step 5 .
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool in DTC and FAILED THIS IGNITION option, quickly depress accelerator pedal to WOT and then quickly release/return pedal to closed throttle position. If this DTC sets, go to next step. If this DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1286: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

The APP sensor No. 1 signal increases as accelerator pedal is depressed from less than 1.1 volt (zero percent with pedal at rest) to greater than 2.1 volts (100 percent pedal travel).
The APP sensor No. 2 signal decreases from greater than 3.9 volts (zero percent pedal travel) to less than 2.9 volts (100 percent pedal travel).
The APP sensor No. 3 signal decreases from greater than 3.2 volts (zero percent pedal travel) to less than 3.1 volts (100 percent pedal travel).

Observe that signal circuits for APP sensor No. 2 and APP sensor No. 3 pull up to 5 volts and APP sensor No. 1 circuit pull to ground within the TAC module. DTC will set APP sensor No. 3 disagrees with APP sensor No. 1 by greater than 13 percent and APP sensor No. 3 disagrees with APP sensor No. 2 by greater than 13 percent and conditions met for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P1518 is also set. If DTC P1518 is set, diagnose DTC first. If DTC P1518 is not set, go to next step.
DO NOT depress accelerator pedal. Start and operate engine at idle. Using scan tool, monitor DTC information. If any other TAC module or APP sensor DTCs set (except P1125), go to applicable DTC test. If no other DTCs are set, go to next step.
Using scan tool, monitor APP SENSOR DISAGREE parameter. If scan tool displays YES for any of the parameters, go to step 6 . If scan tool does not display YES for any of the parameters, go to next step.
Using scan tool, monitor angle of APP sensors No. 1, 2 and 3. Slowly depress accelerator pedal to WOT position stopping briefly at about 25, 50 and 75 percent positions. Slowly return to closed position, stopping briefly at about 75, 50 and 25 percent positions. If APP sensor No. 1 angle corresponds to APP sensors No. 2 and 3 angles, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If APP sensor No. 1 angle does not correspond to APP sensors No. 2 and 3, go to next step.
Turn ignition off. Disconnect APP sensor harness connector. Using a jumper wire, jumper APP sensor No. 3 5-volt reference circuit to a known-good ground. Turn ignition on, with engine off. Using scan tool, monitor TP sensor No. 3 voltage. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 11 .
Jumper APP sensor No. 3 5-volt reference circuit to APP sensor No. 3 ground circuit. If scan tool displays zero volts, go to next step. If scan tool does not display zero volts, go to step 12 .
Jumper APP sensor No. 3 signal circuit to APP sensor No. 3 5-volt reference circuit. If scan tool displays 5 volts, go to step 14 . If scan tool does not display 5 volts, go to next step.
Leave ignition on. Check resistance between APP sensor No. 3 signal circuit to all other circuit in APP sensor connectors. If resistance is 0-5 ohms, go to next step. If resistance is not 0-5 ohms, go to step 13 .
Turn ignition off. Disconnect both TAC module harness connectors. Check continuity between APP sensor No. 3 signal circuit to all other circuits at both TAC module harness connectors. If continuity exists, go to step 17 . If continuity does not exist, go to step 15 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 3 5-volt reference circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 3 ground circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Turn ignition off. Disconnect TAC module harness connector containing APP circuits. Check resistance of APP sensor No. 3 signal circuit. If resistance is 0-5 ohms, go to step 15 . If resistance is not 0-5 ohms, go to step 16 .
Check for poor connections at APP harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 18 .
Check for poor connections at TAC module harness connector. Repair as necessary. After repairs, go to step 20 . If connections are okay, go to step 19 .
Repair open or excessive resistance in affected circuit. After repairs, go to step 20 .
Repair shorted circuits that displayed continuity. After repairs are complete, go to step 20 .
Replace accelerator pedal assembly. After replacing pedal assembly, go to step 20 .
Replace TAC module. After replacing module, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1320: IC MODULE 4X REFERENCE CIRCUIT INTERMITTENT (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

Ignition Control (IC) module creates a 4X and a 24X signal that is used by the PCM for ignition and fuel control. If PCM does not receive 4X reference pulses from IC module for greater than.4 second while engine is running, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC(s) P0232, P0322, P1323 or P1375 is also present. If any of these DTCs are present, diagnose affected DTC(s) first. If DTCs are not present, go to next step.
Disconnect IC module harness connector C3. Turn ignition on. Using DVOM, check voltage between ground and ignition feed circuit at IC module harness connector C3. If voltage reading is 10-15 volts or greater, go to next step. If voltage reading is not 10-15 volts or greater, go to step 10 .
Store fluid life index as indicated on scan tool. Turn ignition switch to LOCK position. Reconnect IC module harness connector C3. Disconnect IC module harness connector C4. Disconnect PCM harness connector C2. Using DVOM, check resistance between ground and fuel control circuit at PCM harness connector. If resistance is greater than 10,000 ohms, go to next step. If measured resistance is not greater than 10,000 ohms, go to step 11 .
Check resistance of fuel control circuit between IC module harness connector and PCM harness connector terminal. If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 12 .
Turn ignition on. Check voltage between ground and fuel control circuit at IC harness connector C2. If voltage reading is less than.5 volt, go to next step. If voltage reading is not less than.5 volt, go to step 13 .
Reconnect IC module harness connector C4. Check voltage between ground and fuel control circuit at PCM harness connector C2. If voltage reading is greater than 4.2 volts, go to next step. If voltage reading is not greater than 4.2 volts, go to step 14 .
Turn ignition off. With PCM harness connector C2 disconnected, remove terminal No. 44 (4X fuel control circuit) from connector. Reconnect PCM harness connector. Using a DVOM set to Hz scale, connect DVOM between ground and terminal No. 44. Start and operate engine at idle. If frequency is less than 30-100 Hz, go to step 14 . If frequency is not less than 30-100 Hz, go to next step.
Remove all jumpers. Reconnect IC module connector C4. Clear DTC. Start and operate engine at idle. Using scan tool, select DTC INFO then FAIL THIS IGN modes. If DTC P1320 resets, go to step 16 . If DTC does not reset, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for no voltage to IC module caused by a faulty fuse due to short in ignition feed circuit, open in ignition feed circuit or shorted IC module. Repair as necessary.
Repair short to ground in fuel control (4X) circuit to IC module.
Repair open in fuel control circuit (4X) to IC module.
Repair short to voltage in fuel control (4X) circuit to IC module.
Check terminal contact at IC module harness connector C4. Repair as necessary. If terminal contact is okay, go to next step.
Replace IC module.
Check fuel control circuit terminal contact at PCM harness connector C2. Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

DTC may set due to a false start condition in which cranking speed exceeds 568 RPM with engine not starting. If no fault is present, check for intermittent open or short in IC module fuel control circuit, ignition feed circuit or ground circuit. Also, check for EMI interference on IC module fuel control circuit.

DTC P1323: IC MODULE 24X REFERENCE CIRCUIT LOW FREQUENCY (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

Ignition Control (IC) module creates a 4X and a 24X signal that is used by the PCM for ignition and fuel control. In this test, PCM checks for 4X reference pulses being received without 24X reference pulses. When engine is running and PCM is receiving 4X pulses without 24X reference pulses and the 24X reference signal line is low for 4 seconds, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC P1376 is also present. If DTC P1376 is present, diagnose this DTC first. If DTC is not present, go to next step.
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect IC module harness connector C4 and PCM harness connector C2. Using DVOM, check resistance between ground and 24X reference circuit at PCM harness connector C2. If resistance is greater than 10,000 ohms, go to next step. If resistance is not greater than 10,000 ohms, go to step 8 .
Check resistance of 24X reference signal circuit between PCM and IC harness connector terminals. If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 9 .
Reconnect IC module harness connector C4. Turn ignition on. Check voltage between ground and 24X reference signal circuit at PCM harness connector C2. If voltage reading is greater than 4.2 volts, go to next step. If voltage reading is not greater than 4.2 volts, go to step 10 .
Turn ignition off. With PCM harness connector disconnected, remove terminal No. 5 (24X spark reference circuit) from connector. Reconnect PCM harness connector. Using a DVOM set to Hz scale, connect DVOM between ground and terminal No. 5. Start and operate engine at idle. If frequency is less than 340 Hz, go to step 10 . If frequency is not less than 340 Hz, go to next step.
Remove all jumper wires. Reconnect IC module connector C4. Clear DTC. Start and idle engine. Using scan tool, select DTC INFO then FAIL THIS IGN modes. If DTC P1323 resets, go to step 12 . If DTC does not reset, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for short to ground in 24X spark reference signal circuit.
Repair open in 24X reference signal circuit.
Check terminal contact at IC module harness connector C4. Repair as necessary. If terminal contact is okay, go to next step.
Replace IC module.
Check 24X reference signal circuit terminal contact at PCM harness connector C2. Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

DTC P1336: CRANKSHAFT NOTCH ADAPTIVE NOT LEARNED (1.9L SATURN)

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

PCM receives signals from Crankshaft Position (CKP) sensor to determine the position at various degrees of rotation. The PCM can then base misfire diagnostics on the principle that crankshaft velocity will increase as each cylinder contributes its power input. The PCM must know precisely the degree of variability in crankshaft notches to perform misfire diagnosis. Replacement of either the PCM or crankshaft requires a "crankshaft learn" procedure, to learn the variability of the crankshaft notches.

DTC will set if learn procedure has not been performed and the vehicle is driven or if crankshaft notch learn process has not been completed and vehicle is driven at greater than 15 MPH.

Do not transfer PCM from one vehicle to another without resetting crankshaft adaptives and performing "crankshaft learn" procedure. Failure to do so may result in false misfire detection. Anytime CKP sensor is replaced, the crankshaft learn procedure must be performed.

The crankshaft notch learn routine will not run if misfire conditions are detected. If other DTCs are present, diagnose and repair affected DTCs first. After repairs, perform "crankshaft learn" procedure using scan tool. On scan tool, view scan tool parameter CRANKSHAFT LEARNED under misfire table. Scan tool will indicate YES when learned procedure is complete.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (2.2L "J" BODY, 2.2L "S" SERIES & 2.4L "J" & "N" BODIES)

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

The crankshaft position system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, the crankshaft balancer interrupter rings, and the crankshaft position sensor hall effect switches. The calculated error allows PCM to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load.

The crankshaft position system variation learning procedure must be performed anytime a change is made to the CKP sensor to crankshaft relationship, or if PCM is replaced or reprogrammed.

DTC P1336 set indicates that the crankshaft position system variation values have not been stored in the PCM and the crankshaft position system variation learn procedure must be performed. The learn procedure is required after the following service procedures have been performed, regardless of whether or not DTC P1336 is set

PCM replacement or reprogramming.
Engine replacement.
Crankshaft balancer replacement.
Crankshaft position sensor replacement.
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

DTC will set when crankshaft position system variation values are not stored in the PCM memory.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform crankshaft position system variation learn position as follows: Install scan tool. Hood closed. Vehicle in Park or Neutral. ECT at 158°F (70°C). Engage parking brake. Block vehicle drive wheels. All accessories off. Enable crankshaft position system variation learning procedure with scan tool. Raise engine speed to 3920 RPM and release throttle as soon as engine cuts out. If scan tool indicates that crankshaft position system variation has been performed, go to step 5 . If scan tool does not indicate that crankshaft position system variation has been performed, go to next step.
Attempt crankshaft position system variation learning procedures for about 10 times. If crankshaft variation has been learned, go to step 5 . If crankshaft variation has not been learned, go to next step.
Check for problem with crank sensor to crankshaft relationship. Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1336 will only set if PCM has not learned the crankshaft position system variation. PCM only needs to learn this variation once per life cycle of vehicle unless the CKP sensor to crankshaft relationship is disturbed. Removing a part for inspection and then reinstalling the same part is considered a disturbance. A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed that ignition cycle.

If engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode. Review crankshaft position system variation learning procedure and re-enable the learn procedure. Verify that scan tool indicates Test In Progress.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

The crankshaft position system variation values are stored in the PCM non-volatile memory after the crankshaft position system variation learn procedure has been performed. DTC P1336 set indicates that the crankshaft position system variation values have not been stored in the PCM and the crankshaft position system variation learn procedure must be performed. The learn procedure is required after the following service procedures have been performed, regardless of whether or not DTC P1336 is set

PCM replacement.
Engine replacement.
Crankshaft balancer replacement.
Crankshaft position sensor replacement.
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

DTC will set when crankshaft position system variation values are not stored in the PCM memory.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform crankshaft position system variation learn procedure.

The crankshaft position system variation compensating values are stored in the PCM's non-volatile memory after a learn procedure has been performed. If actual crankshaft position variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set.

If the crankshaft position system variation learn procedure cannot be performed successfully, check the following conditions and correct as necessary

ECT less than 158°F (70°C).
Allow engine to warm-up to greater than 158°F (70°C).
PCM related DTC(s) set.
Scan tool crankshaft position system variation learn function will be disabled of any PCM DTCs other than DTC P1336 are stored.
Camshaft position signal problem detected.
3X reference signal problem detected.
24X reference signal problem detected.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.5L "W" BODY)

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

PCM replacement.
Engine replacement.
Crankshaft replacement.
Crankshaft position sensor replacement.
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

DTC will set if crankshaft position system variation values are not stored in the PCM memory.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform crankshaft position system variation learn position.

If the crankshaft position system variation learn procedure cannot be performed successfully, check the following conditions and correct as necessary: ECT less than 158°F (70°C), PCM related DTC(s) set or scan tool crankshaft position system variation learn function will be disabled of any PCM DTCs other than DTC P1336 are stored.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.8L "C", "F", "G" & "W" BODIES)

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

The crankshaft position system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, the crankshaft balancer interrupter rings, and the crankshaft position sensor Hall effect switches. The calculated error allows PCM to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load.

PCM replacement.
Engine replacement.
Crankshaft balancer replacement.
Crankshaft position sensor replacement.
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

Conditions for setting DTC are: no CMP or CKP sensor DTCs set, ECT is greater than 158°F (70°C) and crankshaft position system variation values are not stored in the PCM memory.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform crankshaft position system variation learn position.

If the crankshaft position system variation learn procedure cannot be performed successfully, check the following conditions and correct as necessary

ECT less than 158°F (70°C).
Allow engine to warm-up to greater than 158°F (70°C).
PCM related DTC(s) set.
Scan tool crankshaft position system variation learn function will be disabled of any PCM DTCs other than DTC P1336 are stored.
Camshaft position signal problem detected.
3X reference signal problem detected.
18X reference signal problem detected.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

The Crankshaft Position (CKP) sensor sends pulses to VCM as the reluctor teeth rotate past the CKP sensor. VCM uses the CKP pulses to synchronize ignition and fuel injector operation, and to time interval between each CKP pulse. VCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with previous interval.

A misfire causes an unexpected change in crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes more than expected amount, VCM interprets this as a misfire. Interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the crankshaft, reluctor and CKP sensor components make misfire detection difficult.

VCM learns variations during CKP system variation learning procedure. VCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command VCM to perform CKP system variation learning procedure again. Perform learning procedure after VCM replacement, any operation or repair involving crankshaft, CKP sensor or CKP sensor-to-reluctor wheel gap relationship, engine replacement or when ignition switch was left in ON position until battery drained.

Note. Removing power to VCM with ignition on may clear/erase stored pulse value and set this DTC.

Reprogramming VCM does not require running the CKP system variation learn procedure unless VCM is new or from another vehicle. DTC will set when VCM has not learned the crankshaft position system variation.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform CKP Variation Learning procedure as follows: Install scan tool. Apply parking brakes and block drive wheels. Close hood. Place transmission in Park (A/T) or Neutral (M/T). Warm engine to 150°F (65°C). Turn off all accessories. Apply service brakes for duration of procedure. Enable CKP SYSTEM VARIATION LEARN PROC. on scan tool. Slowly increase engine speed to 4000 RPM. Immediately release throttle when engine speed decreases. If scan tool shows CKP learn procedure is complete, go to step 5 . If scan tool does not show CKP learn procedure is complete, go to next step.
Attempt CKP learn procedure as many as 3 times. If scan tool indicates that learn procedure is complete, go to step 5 . If scan tool does not indicate that learn procedure is complete, go to next step.
Check CKP sensor and crankshaft reluctor wheel for damage. If problem is found, go to step 6 . If no problem is found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off for 15 seconds, then go to step 7 .
Replace CKP sensor and/or reluctor wheel. After replacing CKP sensor, perform CKP System Variation Learn Procedures. See step 2 . After performing learn procedures, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If CKP learn procedure cannot be learned, check for a chipped or damaged reluctor wheel, incorrect CKP sensor alignment to reluctor wheel, excessive crankshaft runout, interference in signal circuit to CKP sensor or incorrect ratio of crankshaft to camshaft pulses.

If PCM receives an incorrect crankshaft to camshaft ratio, PCM will not allow scan tool to enable the learn procedure.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (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.

The Crankshaft Position (CKP) sensor sends pulses to PCM as the reluctor teeth rotate past the CKP sensor. PCM uses the CKP pulses to synchronize ignition and fuel injector operation, and to time interval between each CKP pulse. PCM determines when an excessive change in crankshaft speed occurs by comparing each new time interval with previous interval.

A misfire causes an unexpected change in crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes more than expected amount, PCM interprets this as a misfire. Interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the crankshaft, reluctor and CKP sensor components make misfire detection difficult.

PCM learns variations during CKP system variation learning procedure. PCM compensates for these variations when performing detect misfire calculations. Only a scan tool can command PCM to perform CKP system variation learning procedure again. Perform learning procedure after the following actions

VCM replacement.
Any operation or repair involving crankshaft, CKP sensor or CKP sensor-to-reluctor wheel gap relationship.
Engine replacement.
Ignition switch left in ON position until battery is drained.

Note. Removing power to VCM with ignition on may clear/erase stored pulse value and set this DTC.

Reprogramming VCM does not require running the CKP system variation learn procedure unless VCM is new or from another vehicle. DTC will set when, engine is running, no CKP or CMP sensor DTCs present and VCM has not learned the CKP system variation.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform CKP Variation Learn procedure as follows: Install scan tool. Apply parking brakes and block drive wheels. Close hood. Place transmission in Park (A/T) or Neutral (M/T). Warm engine to 150°F (65°C). Turn off all accessories. Apply service brakes for duration of procedure. Enable CKP SYSTEM VARIATION LEARN PROC. on scan tool. Slowly raise engine speed to 4000 RPM. Immediately release throttle when engine speed decreases. If scan tool shows CKP learn procedure is complete, go to step 5 . If scan tool does not show CKP learn procedure is complete, go to next step.
Attempt CKP learn procedure as many as 3 times. If scan tool indicates that learn procedure is complete, go to step 5 . If scan tool does not indicate that learn procedure is complete, go to next step.
Check CKP sensor and crankshaft reluctor wheel for damage. If problem is found, go to step 6 . If no problem is found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off for 15 seconds, then go to step 8 .
Replace CKP sensor and/or reluctor wheel. After replacing components, perform CKP learn procedures. See step 2 . After performing CKP learn procedures, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If PCM receives an incorrect crankshaft to camshaft ratio, PCM will not allow scan tool to enable the learn procedure.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

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

A misfire causes an unexpected change in crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes more than expected amount, PCM interprets this as a misfire. Interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the crankshaft, reluctor and CKP sensor components make misfire detection difficult.

PCM replacement.
Any operation or repair involving crankshaft, CKP sensor or CKP sensor-to-reluctor wheel gap relationship.
Engine replacement.
Ignition switch in ON position until battery is drained.

Note. Removing power to PCM with ignition on may clear/erase stored pulse value and set this DTC.

Reprogramming PCM does not require running the CKP system variation learn procedure unless PCM is new or from another vehicle. DTC will set when PCM has not learned the CKP system variation.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform CKP Variation Learning procedure as follows: Install scan tool. Apply parking brakes and block drive wheels. Close hood. Place transmission in Park (A/T) or Neutral (M/T). Warm engine to 150°F (65°C). Turn off all accessories. Apply service brakes for duration of procedure. Enable CKP SYSTEM VARIATION LEARN PROC. on scan tool. Slowly raise engine speed to 4000 RPM. Immediately release throttle when engine speed decreases. If scan tool shows CKP learn procedure is complete, go to step 5 . If scan tool does not show CKP learn procedure is complete, go to next step.
Attempt CKP learn procedure as many as 3 times. If scan tool indicates that learn procedure is complete, go to step 5 . If scan tool does not indicate that learn procedure is complete, go to next step.
Check CKP sensor and crankshaft reluctor wheel for damage. If problem is found, go to step 6 . If no problem is found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off for 15 seconds, then go to step 7 .
Replace CKP sensor and/or reluctor wheel. After replacing components, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If PCM receives an incorrect crankshaft to camshaft ratio, PCM will not allow scan tool to enable the learn procedure.

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (5.7L "F" BODY)

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

A misfire causes an unexpected change in crankshaft speed. A certain amount of acceleration/deceleration is expected between each firing stroke, but if crankshaft speed changes more than expected amount, PCM interprets this as a misfire. Interval between CKP sensor pulses is extremely small. At high engine speeds, slight variations in the crankshaft, reluctor and CKP sensor components make misfire detection difficult.

PCM replacement.
Any operation or repair involving crankshaft, CKP sensor or CKP sensor-to-reluctor wheel gap relationship.
Engine replacement.
Ignition switch left in ON position until battery is drained.

Note. Removing power to PCM with ignition on may clear/erase stored pulse value and set this DTC.

Reprogramming PCM does not require running the CKP system variation learn procedure unless PCM is new or from another vehicle.

Conditions for setting DTC are: no CKP or CMP sensor DTCs present and PCM has not learned the CKP system variation.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Perform CKP Variation Learning procedure as follows: Install scan tool. Apply parking brakes and block drive wheels. Close hood. Place transmission in Park (A/T) or Neutral (M/T). Warm engine to 150°F (65°C). Turn off all accessories. Apply service brakes for duration of procedure. Enable CKP SYSTEM VARIATION LEARN PROC on scan tool. Slowly raise engine speed to 4000 RPM. Immediately release throttle when engine speed decreases. If scan tool shows CKP learn procedure is complete, go to step 5 . If scan tool does not show CKP learn procedure is complete, go to next step.
Attempt CKP learn procedure as many as 3 times. If scan tool indicates that learn procedure is complete, go to step 5 . If scan tool does not indicate that learn procedure is complete, go to next step.
Check CKP sensor and crankshaft reluctor wheel for damage. If problem is found, go to step 6 . If no problem is found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off for 15 seconds, then go to step 7 .
Replace CKP sensor and/or reluctor wheel. After replacing components, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If PCM receives an incorrect crankshaft to camshaft ratio, PCM will not allow scan tool to enable the learn procedure.

DTC P1345: CRANKSHAFT/CAMSHAFT POSITION SENSOR CORRELATION (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 monitors the CKP and CMP signals to determine if they are synchronized. If both signals are not observed by the VCM within a specified time, VCM will determine that error has occurred. DTC will set when engine is running, cam sensor reference pulse is not detected at correct relative position with crank pulse.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start engine. Using scan tool, monitor engine RPM. If engine RPM fluctuates up to twice the expected RPM, go to next step. If engine RPM does not fluctuate up to twice the expected RPM, go to step 4 .
Replace crankshaft position sensor. After replacing sensor, go to step 10 .
Start engine. Raise engine speed to 1000 RPM. Monitor camshaft retard on scan tool. If camshaft retard is -2 to 2 degrees, go to next step. If camshaft retard is not -2 to 2 degrees, go to step 6 .
Increase engine speed to 2000 RPM. Check camshaft retard on scan tool. If camshaft retard changes more than 2 degrees of previous reading, go to next step. If camshaft retard does not change more than 2 degrees of previous reading, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for proper installation of distributor. Remove distributor cap and gently attempt to rotate rotor. If rotor turns on distributor shaft, go to step 9 . If rotor does not turn on distributor shaft, go to next step.
Check for proper installation of distributor. Repair as necessary. After repairs, go to step 10 . If distributor installation is okay, go to next step.
Perform Camshaft Retard Offset adjustment as follows: Turn engine off. Slightly loosen distributor hold-down bolt. Start and operate engine at 1000 RPM. Using scan tool, monitor camshaft retard offset. To compensate to a negative reading, rotate distributor counterclockwise. To compensate for positive reading, rotate distributor clockwise. Set offset to zero degrees, then tighten distributor hold-down bolt. If zero degrees is obtained, go to next step. If zero degrees cannot be obtained, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace distributor. After replacing distributor, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for loose CMP sensor, excessive free play in timing chain and gear assembly, incorrectly installed distributor, loose rotor or distributor hold-down bolt. An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation.

DTC P1345: CRANKSHAFT/CAMSHAFT POSITION SENSOR CORRELATION (4.3L "C", "K", L", "M", "S" & "T" SERIES)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start engine. Using scan tool, monitor engine RPM. If engine RPM fluctuates up to twice the expected RPM, go to next step. If engine RPM does not fluctuate up to twice the expected RPM, go to step 4 .
Replace crankshaft position sensor. After replacing sensor, go to step 9 .
Install scan tool. Start engine. Raise engine speed to 1000 RPM. Monitor camshaft retard on scan tool. If camshaft retard is -5 to -17 degrees, go to next step. If camshaft retard is not -5 to -17 degrees, go to step 6 .
Raise engine speed to 2000 RPM. Check camshaft retard on scan tool. If camshaft retard changes more than 2 degrees of previous reading, go to next step. If camshaft retard does not change more than 2 degrees of previous reading, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for proper installation of distributor. Remove distributor cap and gently attempt to rotate rotor. If rotor turns on distributor shaft, go to step 8 . If rotor does not turn on distributor shaft, go to next step.
Check distributor for proper installation. Repair as necessary. After repairs, go to step 9 . If distributor installation is okay, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace distributor. After replacing distributor, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1350: IGNITION CONTROL (IC) SYSTEM (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

Under normal operation, until engine RPM is high enough for the PCM to control spark, PCM will open the by-pass circuit to the IC module, the IC module will then ground the IC module circuit. This mode is called the module mode, because the IC module is controlling the spark at his point. Once engine speed is high enough (about 65 RPM), the 4X reference pulses are received and if no PCM faults are detected, PCM will close the by-pass line and in response the IC module will unground the IC circuit, allowing PCM to control spark. This mode is called the control mode.

This test is used to check for faults in both the by-pass and the IC circuit. To check both circuits, this diagnostic runs 2 tests. One during crank and one while engine is running. If IC control pulses are detected by the PCM on the IC line while in module mode (cranking) or if no ignition control pulses are detected by the PCM while in ignition control mode (running), DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, check if DTC P0322, P0372, P1323, P1371 or P1376 is also present. If any of these DTCs are present, diagnose affected DTC(s) first. If DTCs are not present, go to next step.
Turn ignition off. Wait 30 seconds then turn ignition on, with engine off. Using scan tool, record snapshot information for DTC P1350. Clear DTC P1350. After clearing DTC, start engine. Check if DTC P1350 fails in this ignition cycle. If DTC fails, go to next step. If DTC does not fail in this ignition cycle, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Store fluid life index as indicated on scan tool. Turn ignition off. Wait 30 seconds then disconnect PCM harness connector C2 and IC module connector C4. Using DVOM, check for high resistance, short to ground or short to voltage in by-pass and ignition control circuit. Repair as necessary. If circuits are okay, go to next step.
Turn ignition off. Reconnect PCM harness connector. Turn ignition on, but do not crank engine. Using DVOM, check voltage between ground and by-pass circuit, and between ground and ignition control circuit. If voltage reading is less than one volt, go to next step. If voltage reading is not less than one volt, go to step 11 .
Turn ignition off. Wait 30 seconds then disconnect IC module harness connector C4. Using 6-Pin IC module diagnostic jumpers, jumper the following IC module connector C4 terminals to the following module terminals: C4 Terminal "A" To Module Pin "A" C4 Terminal "B" To Module Pin "B" C4 Terminal "C" To Module Pin "C" C4 Terminal "D" To Module Pin "D" C4 Terminal "E" To Module Pin "E" C4 Terminal "F" To Module Pin "F" Start and operate engine at idle. Check voltage to ground on ignition control circuit from PCM. If voltage is fixed at about 1.7 volts, go to next step. If voltage is not fixed at about 1.7 volts, go to step 11 .
Check voltage to ground on by-pass circuit from PCM. If voltage reading is less than one volt, go to next step. If voltage reading is not less than one volt, go to step 11 .
Momentarily ground ignition control circuit. Check voltage to ground in by-pass circuit from PCM. If voltage reading is 4.7 volts or greater, go to next step. If voltage reading is not 4.7 volts or greater, go to step 11 .
Check terminal contact at IC module harness connector C4. Repair as necessary. If terminal is okay, go to next step.
Replace IC module.
Check terminal contact at PCM harness connector C2. Repair as necessary. If terminal contacts are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

If fault is not present, check terminal contact at IC module and PCM harness connectors.

DTC P1351: IGNITION CONTROL (IC) CIRCUIT OPEN (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

The Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When the second 3X reference pulse is recognized by the PCM, PCM applies 5 volts to by-pass circuit, commanding ICM to switch spark advance to PCM control (IC mode). If PCM detects an open in the IC circuit, DTC will set. Engine will start and may run in by-pass mode timing.

DTC will set when engine is running and PCM detects an open in IC circuit.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect PCM harness connector. Check resistance between IC and reference low circuit. If resistance is less than 500 ohms, go to step 4 . If resistance is not less 500 ohms, go to next step.
Disconnect ICM harness connector. Check for open in IC circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 5 .
Check for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to step 7 .
Check for poor terminal connections at ICM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
Replace ICM. After replacing module, go to step 8 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC FAILED THIS IGN, return to step 2 . If scan tool does not display DTC FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

DTC P1351: IGNITION CONTROL (IC) NO. 1 CIRCUIT OPEN (3.5L "W" BODY)

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

Ignition system uses an individual coil for each cylinder. Ignition coil assembly, located in center of each valve cover, consists of 3 coils and an ignition control module, allowing coil to connect directly to spark plugs using only a boot. Each module (bank 1 and bank 2) controls 3 ignition coils for that bank of cylinders. PCM controls ignition module operation.

There are 6 Ignition Control (IC) circuits, one per cylinder, that connects the PCM and ignition modules. Each ignition modules are equipped with power feed, chassis ground and reference low circuits. PCM causes spark to occur by pulsing the IC circuit, which signals the ignition module to trigger ignition coil and fire the spark plug. Sequencing and timing are PCM controlled.

Conditions for running DTC are, ignition voltage at 9-17 volts and conditions are met for less than one second. DTC will set when PCM detects an incorrect voltage potential in ignition control circuit.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1351: IGNITION CONTROL (IC) CIRCUIT OPEN (3.8L "C", "F", "G", "H" & "W" BODIES)

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

DTC will also set when PCM detects an open in IC circuit and condition is present for 300 3X periods (100 crankshaft revolutions).

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect PCM harness connector. Connect DVOM between IC and reference low circuits. Turn ignition on. Using test light connected to battery voltage, probe by-pass circuit. If resistance is greater than 500 ohms, go to step 4 . If resistance is not greater than 500 ohms, go to next step.
Turn ignition off. Disconnect ICM connector. Check IC circuit for open circuit. Repair as necessary. After repairs, go to step 8 . If circuit is open, go to step 5 .
Check for faulty IC circuit connection at PCM. Repair as necessary. After repairs, go to step 8 . If connection is okay, go to step 7 .
Check for faulty IC circuit connection at ICM. Repair as necessary. After repairs, go to step 8 . If connection is okay, go to next step.
Replace ICM. After replacing module, go to step 8 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, system is okay.

Check for faulty connections or damaged harness to ICM and PCM. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harnesses and connectors. A change in voltage display indicates fault location.

DTC P1351: IGNITION CONTROL (IC) 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.

Enhanced ignition system provides timing input to VCM with a crank sensor. VCM utilizes reference pulse to determine individual ignition spark timing for each cylinder.

Once VCM calculates ignition timing, timing signal is sent to ignition coil module. Each timing pulse received by ignition coil module triggers module operation of ignition coil. Secondary ignition voltage is induced then sent to distributor for distribution to each spark plug. IC signal voltage ranges from about 0.5 volt to 4.5 volts.

DTC will set when EST is enabled, engine speed is less than 250 RPM and EST voltage is greater than 4.9 volts.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. Disconnect injector connector. Crank engine for 30 seconds. Check if DTC P1351 is set. If DTC P1351 is set, go to next step. If DTC P1351 is not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Reconnect injector connector. Disconnect ignition control module harness connector. Using DVOM in A/C scale and connected to ground, probe ignition control module harness connector terminal "B". Crank engine and note voltage reading. If voltage reading is 1-4 volts, go to step 9 . If voltage reading is not 1-4 volts, go to next step.
Turn ignition off. Disconnect VCM harness connector. Using DVOM, check for open in IC control circuit between VCM harness connector terminal No. 9 and ignition control module harness connector terminal "B". If circuit is open, go to next step. If circuit is okay, go to step 6 .
Repair open in IC control circuit between VCM and ignition control module. After repairs, go to step 17 .
Reconnect VCM harness connector. Turn ignition on, with engine off. Check voltage between ground and ignition control module harness connector terminal "B". If voltage reading is greater than one volt, go to next step. If voltage reading is not greater than one volt, go to step 8 .
Repair short to voltage in IC control circuit between VCM and ignition control module. After repairs, go to step 17 .
Check for poor VCM connection. If connection is faulty, go to step 15 . If connection is okay, go to step 16 .
Turn ignition off. Using test light connected to battery voltage, probe ignition control module harness connector terminal "C". If test light illuminates, go to step 11 . If test light does not illuminate, go to next step.
Repair open in ignition control module ground circuit. After repairs, go to step 17 .
Turn ignition on. Using test light connected to ground, probe ignition control module harness connector terminal "A". If test light illuminates, go to step 13 . If test light does not illuminate, go to next step.
Repair open in ignition control module ignition feed circuit. After repairs, go to step 17 .
Check for poor connection at ignition control module. If a problem is found, go to step 15 . If no problem is found, go to next step.
Replace ignition control module. After replacing module, go to step 17 .
Repair circuit as necessary. After repairs, go to step 17 .
Replace VCM. Program replacement VCM using required equipment and perform CKP Variation Learn Procedure. See DTC P1336 test. After replacing VCM, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect VCM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.

If connections and harness are okay, using DVOM connected between ignition feed circuit and IC control circuit of VCM connector, monitor voltage while wiggling related connectors and wiring harnesses. If a failure is induced, voltage will change. A change in voltage will assist in isolating location of fault.

DTC P1351: IGNITION CONTROL (IC) CIRCUIT HIGH VOLTAGE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

Crankshaft Position (CKP) sensor provides VCM with reference pulse input. VCM uses CKP input to determine ignition spark timing for each cylinder. Once VCM calculates ignition timing, it sends a signal to ignition coil module on IC circuit. DTC will set when IC voltage is greater than 4.9 volts.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. Disconnect fuel injector connector. Crank engine for 15 seconds. Read DTCs. If this DTC resets, go to next step. If this DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Reconnect fuel injector connector. Disconnect ignition coil module connector. Using DVOM in AC scale, check voltage between engine ground and IC control circuit at ignition coil module, while cranking engine. If voltage reading is 1-4 volts, go to step 9 . If voltage reading is not 1-4 volts, go to next step.
Turn ignition off. Disconnect VCM harness connector. Check for open in IC control circuit between VCM harness connector terminal No. 9 and ignition coil module harness connector terminal "B". If circuit is open, go to next step. If resistance is not open, go to step 6 .
Repair open IC control circuit between VCM and ignition coil module. After repairs, go to step 17 .
Reconnect VCM harness connector. Turn ignition on, with engine off. Check voltage between ground and ignition control module harness connector terminal "B". If voltage reading is greater than one volt, go to next step. If voltage reading is not greater than one volt, go to step 8 .
Repair short to voltage in IC control circuit between VCM and ignition control module. After repairs, go to step 17 .
Check for poor VCM harness connections. If connections are faulty, go to step 15 . If connections are okay, go to step 16 .
Turn ignition off. Connect a test light between battery voltage and ignition coil module harness connector ground circuit. If test light illuminates, go to step 11 . If test light does not illuminate, go to next step.
Repair open ignition coil module ground circuit. After repairs, go to step 17 .
Turn ignition on. Connect test light between engine ground and ignition coil module harness connector ignition feed circuit, and then ignition coil module harness connector tachometer signal circuit. If test light illuminates on both circuits, go to step 13 . If test light does not illuminate on both circuits, go to next step.
Repair faulty circuit. After repairs, go to step 17 .
Check for poor connection at ignition coil module. If connection is faulty, go to step 15 . If connection is okay, go to next step.
Replace ignition coil module. After replacing module, go to step 16 .
Repair faulty connection. After repairs, go to next step.
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 .
Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

DTC P1352: BY-PASS LINE OPEN (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect DVOM between IC and reference low circuit. Connect test light between battery voltage and by-pass circuit. If resistance is greater than 5000 ohms, go to step 4 . If resistance is not greater than 5000 ohms, go to next step.
Turn ignition off. Disconnect ICM harness connector. Check for open in by-pass circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 5 .
Check for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to step 7 .
Check for poor terminal connections at ICM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
Replace ICM. After replacing module, go to step 8 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.

DTC P1352: IGNITION CONTROL (IC) NO. 2 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1352: BY-PASS CIRCUIT OPEN (3.8L "C", "F", "G", "H" & "W" BODIES)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect DVOM between IC and reference low circuit. Connect test light between battery voltage and by-pass circuit. If resistance is greater than 5000 ohms, go to step 4 . If resistance is not greater than 5000 ohms, go to next step.
Turn ignition off. Disconnect ICM harness connector. Check for open in by-pass circuit. Repair as necessary. After repairs, go to step 8 . If circuit is okay, go to step 5 .
Check for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to step 7 .
Check for poor terminal connections at ICM. Repair as necessary. After repairs, go to step 8 . If connections are okay, go to next step.
Replace ICM. After replacing module, go to step 8 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays DTC FAILED THIS IGN, return to step 2 . If scan tool does not display DTC FAILED THIS IGN, repair is complete.

DTC P1353: IGNITION CONTROL (IC) NO. 3 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1354: IGNITION CONTROL (IC) NO. 4 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1355: IGNITION CONTROL (IC) NO. 5 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1356: IGNITION CONTROL (IC) NO. 6 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

Condition required to set DTC are, PCM senses IC pulses during crank while by-pass mode spark advance is commanded, engine speed greater than 600 RPM and DTC P1350 not set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, clear DTCs. Start engine and allow it to idle for 2 minutes. Read DTCs. If DTC P1361 sets, go to next step. If DTC does not set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect PCM connectors. Turn ignition on. Connect a test light between battery voltage and PCM harness connector by-pass circuit. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
Turn ignition on. With test light still connected between battery voltage and PCM harness connector by-pass circuit, use a DVOM to check resistance between PCM harness connector IC circuit and reference low circuit. If resistance is greater than 6000 ohms, go to step 12 . If resistance is not greater than 6000 ohms, go to next step.
Turn ignition off. Disconnect ICM 14-pin harness connector. Check resistance between ICM 14-pin harness connector IC circuit and engine ground. If resistance is infinite, go to next step. If resistance is not infinite, go to step 10 .
Check by-pass circuit for open. If open is found, repair as necessary. After repairs, go to step 15 . If circuit is open, go to next step.
Check by-pass circuit for faulty connection at ICM. If faulty connection is found, repair as necessary. After repairs, go to step 15 . If connection is okay, go to step 14 .
Turn ignition off. Disconnect ICM 14-pin harness connector. Turn ignition on. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 14 .
Turn ignition off. Disconnect ICM harness connectors. Turn ignition on. Check IC circuit for short to voltage. If short to voltage is found, repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
Locate and repair short to ground in IC circuit. After repairs, go to step 15 .
Locate and repair short to ground in by-pass circuit. After repairs, go to step 15 .
Check by-pass circuit for faulty connection at PCM. If faulty connection is found, repair as necessary. After repairs, go to step 15 . If connection is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 15 .
Replace ICM. After replacing ICM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harnesses and connectors. A change in voltage display indicates fault location.

DTC P1361: IGNITION CONTROL (IC) NO. 1 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.8L "C", "G", "H" & "W" BODIES)

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

Ignition Control Module (ICM) sends signals that PCM requires for fuel control and spark advance calculations. At start of engine crank, ICM controls spark advance (by-pass mode). When second 3X signal is recognized by PCM, it applies 5 volts to by-pass circuit, commanding ICM to switch Ignition Control (IC) of spark advance to PCM (IC mode). A short in IC circuit, or an open or short ground in by-pass circuit will set this DTC. Condition for setting DTC are, PCM does not monitor IC pulses while IC mode spark advance is commanded and condition is present for 300 3X reference periods (100 crankshaft revolution).

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, clear DTCs. Start engine and allow it to idle for 2 minutes. Read DTCs. If DTC P1362 is also present, go to step 6 . If DTC P1362 is not present, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect a test light between ground and IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Turn ignition on. Disconnect IC module connector. Turn ignition on. Using test light connected to ground, probe IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
Locate and repair short to voltage in IC circuit. After repairs are complete, go to step 14 .
Turn ignition off. Disconnect IC module and PCM harness connectors. Connect test light between battery voltage and IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
Locate and repair short to ground in IC circuit. After repairs are complete, go to step 14 .
Turn ignition off. Leave IC module and PCM harness connectors disconnected. Connect test light between ground and IC by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
Locate and repair short to ground in IC by-pass circuit. After repairs, go to step 14 .
Locate and repair short between IC and by-pass circuits. After repairs, go to step 14 . If circuit is okay, go to next step.
Reconnect IC module connector. Leave PCM connector disconnected. Turn ignition on. Connect DVOM between IC and reference low circuits. Connect test light to battery voltage. If resistance switches from less than 500 ohms to 5000 ohms when test light is connected bypass circuit, go to step 13 . If resistance is not as indicated, go to next step.
Replace ICM. After replacing module, go to step 14 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, system is okay.

Check for faulty connections or damaged harness to ICM or PCM. Disconnect ICM. Connect a DVOM between ICM harness connector IC circuit and battery voltage. With ignition on, observe DVOM while moving all related harnesses and connectors. A change in voltage display indicates fault location.

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.8L "F" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. Start and allow engine to idle for 2 minutes. Read DTCs. If DTC P1361 resets, go to next step. If DTC P1362 does not reset, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect a test light between battery voltage and by-pass circuit at PCM connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
Turn ignition on. Connect test light between battery voltage and by-pass circuit. Check resistance between IC circuit and reference low circuit. If resistance is greater than 6000 ohms, go to step 9 . If resistance is not greater than 6000 ohms, go to next step.
Turn ignition off. Disconnect IC module harness connector. Connect test light between battery voltage and IC circuit. If test light illuminates, go to step 10 . If test light does not illuminate, go to next step.
Check for open circuit in by-pass circuit. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
Check by-pass circuit for poor terminal connection at ICM. Repair as necessary. After repairs are complete, go to step 14 . If connection is okay, go to step 13 .
Turn ignition off. Disconnect IC module harness connector. Turn ignition on. Connect test light between battery voltage and by-pass circuit. If test light illuminates, go to step 11 . If test light does not illuminate, go to step 14 .
Turn ignition off. Disconnect ICM connector. Turn ignition on. Check IC circuit for short to voltage. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to step 12 .
Locate and repair short to ground in IC circuit. After repairs, go to step 14 .
Locate and repair short to ground in by-pass circuit. After repairs, go to step 14 .
Check by-pass circuit for poor terminal connection at PCM connector. Repair as necessary. After repairs, go to step 14 . If connection is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, system is okay.

DTC P1361: IGNITION CONTROL (IC) CIRCUIT LOW VOLTAGE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. Disconnect fuel injector connector. Crank engine 15 seconds. Read DTCs. If this DTC resets, go to next step. If this DTC does not reset, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Reconnect fuel injector connector. Disconnect ignition coil module connector. Using DVOM in AC scale, check voltage between engine ground and IC control circuit at ignition coil module, while cranking engine. If voltage reading is 1-4 volts, go to step 6 . If voltage reading is not 1-4 volts, go to next step.
Turn ignition off. Disconnect VCM harness connector. Connect a test light between battery voltage and ignition coil module harness connector IC control circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
Repair short to voltage in IC control circuit. After repairs, go to step 12 .
Turn ignition off. Using test light connected to battery voltage, probe IC module harness connector terminal "C". If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
Repair open in IC module ground circuit. After repairs, go to step 12 .
Check for poor IC module connection. If connection is faulty, go to step 10 . If connection is okay, go to next step.
Replace ignition coil module. After replacing module, go to step 12 .
Repair as necessary. After repairs, go to step 12 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, perform CKP System Variation Learning Procedure. See DTC P1336. After performing CKP learning procedure, go to next step.
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 .
Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

DTC P1361: IGNITION CONTROL (IC) 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.

Enhanced ignition system provides timing input to VCM with a crank sensor. VCM utilizes reference pulse to determine individual ignition spark timing for each cylinder.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. Disconnect injector connector. Crank engine for 15 seconds. Check if this DTC resets. If this DTC resets, go to next step. If this DTC did not reset, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Reconnect injector connector. Disconnect ignition coil module connector. Using DVOM in AC scale, probe ignition coil module harness connector terminal "B" and ground. Crank engine and note voltage reading. If voltage reading is 1-4 volts, go to step 6 . If voltage reading is not 1-4 volts, go to next step.
Turn ignition off. Disconnect VCM harness connector. Using test light connected to battery voltage, probe IC control circuit on VCM harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
Repair short to ground in IC control circuit. After repairs, go to step 12 .
Turn ignition off. Using test light connected to battery voltage, probe IC control circuit on VCM harness connector. If test light illuminates, go to step 8 . If test light does not illuminate, go to next step.
Repair open in ignition coil module ground circuit. After repairs, go to step 12 .
Check for poor ignition control module connection. If connection is faulty, go to step 10 . If connection is okay, go to next step.
Replace ignition control module. After replacing module, go to step 12 .
Repair ignition coil module connection. After repairs, go to step 12 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1362: BY-PASS CIRCUIT SHORTED (3.1L "W" BODY & 3.4L "N" BODY & "U" SERIES)

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

Ignition Control Module (ICM) sends signals that the PCM requires for fuel control and spark advance calculations. At the start of engine crank, the ICM control spark advance (by-pass mode). When the second 3X reference pulse is recognized by the PCM, PCM applies 5 volts to by-pass circuit, commanding ICM to switch spark advance to PCM control (IC mode).

If PCM detects a short to voltage in by-pass circuit, DTC will set. A short to ground in the IC circuit or by-pass circuit will cause both DTCs P1361 and P1362 to set. Engine will start and run in by-pass mode timing. DTC will set when engine is running and PCM detects a short to voltage in by-pass circuit.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P1361 is also set. If DTC P1361 is set, diagnose DTC P1361 first. If DTC P1361 is not set, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Using a test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Turn ignition off. Leave PCM disconnected. Disconnect ICM harness connector. Turn ignition on. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
Locate and repair short to voltage in by-pass circuit. After repairs, go to step 14 .
Turn ignition off. Disconnect ICM and PCM harness connectors. Using test light connected to battery voltage, probe IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
Locate and repair short to ground in IC circuit. After repairs are complete, go to step 14 .
Leave ignition off, ICM and PCM connectors disconnected. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
Locate and repair short to ground in by-pass circuit. After repairs, go to step 14 .
Leave ignition off, ICM and PCM connectors disconnected. Check for short between IC and by-pass circuits. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
Leave ignition off and PCM connector disconnected. Reconnect IC module connector. Using DVOM, check resistance between IC and reference low circuits while probing by-pass circuit using test light connected to battery voltage. If resistance switches from less than 500 ohms to greater than 5000 ohms, go to step 13 . If resistance does not switch from less than 500 ohms to greater than 5000 ohms, go to next step.
Replace IC control module. After replacing module, go to step 14 .
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
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 .

DTC P1362: IGNITION CONTROL (IC) NO. 2 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1362: BY-PASS CIRCUIT SHORTED (3.8L "C", "F", "G", "H" & "W" BODIES)

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

If PCM detects a short to voltage in by-pass circuit, DTC will set. A short to ground in IC or by-pass circuit will cause both DTCs P1361 and P1362 to set. Engine will start and run in by-pass mode timing. DTC will set when engine is running and PCM detects a short to voltage in by-pass circuit.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Clear DTCs. If DTC P1361 is set, go to step 6 . If DTC P1361 is not set, go to next step.
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Using a test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Turn ignition off. Leave PCM disconnected. Disconnect ICM harness connector. Turn ignition on. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 12 .
Locate and repair short to voltage in by-pass circuit. After repairs, go to step 14 .
Turn ignition off. Disconnect ICM and PCM harness connectors. Using test light connected to battery voltage, probe IC circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 8 .
Locate and repair short to ground in IC circuit. After repairs are complete, go to step 14 .
Leave ignition off, ICM and PCM connectors disconnected. Using test light connected to ground, probe by-pass circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
Locate and repair short to ground in by-pass circuit. After repairs, go to step 14 .
Leave ignition off, ICM and PCM connectors disconnected. Check for short between IC and by-pass circuits. Repair as necessary. After repairs, go to step 14 . If circuit is okay, go to next step.
Leave ignition off and PCM connector disconnected. Reconnect IC module connector. Using DVOM, check resistance between IC and reference low circuits while probing by-pass circuit using test light connected to battery voltage. If resistance switches from less than 500 ohms to greater than 5000 ohms, go to step 13 . If resistance does not switch from less than 500 ohms to greater than 5000 ohms, go to next step.
Replace IC control module. After replacing module, go to step 14 .
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
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 .

DTC P1363: IGNITION CONTROL (IC) NO. 3 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1364: IGNITION CONTROL (IC) NO. 4 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace ignition control module. After replacing module, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1365: IGNITION CONTROL (IC) NO. 5 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1366: IGNITION CONTROL (IC) NO. 6 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. If engine starts, problem is intermittent. See DIAGNOSTIC AIDS. If engine does not start, install scan tool. Using scan tool, monitor ignition control status for this cylinder. If scan tool continuously displays OK, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not continuously display OK, go to next step.
Check if entire bank of cylinders are inoperative. If entire bank of cylinders are inoperative, go to next step. If entire bank of cylinders are not inoperative, go to step 8 .
Check ignition system fuses. If fuses are okay, go to next step. If fuses are open/blown, go to step 12 .
Turn ignition off. Disconnect harness connector from ignition control module for affected cylinders. Turn ignition on. Using a test light connected to ground, probe ignition feed circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Connect test light between ignition feed and ground circuit in ignition control module harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14 .
Using a DVOM, check resistance between reference low and ground circuit in ignition control module harness connector. If DVOM reading is 5 ohms or less, go to next step. If DVOM reading is not 5 ohms or less, go to step 15 .
Turn ignition off. Remove fuel pump fuse. Disconnect ignition control module harness connector. Set DVOM to AC Hertz scale. Connect DVOM between ground and affected ignition control circuit. Crank engine. Check frequency on affected ignition control circuit. If frequency is 2-20 Hz, go to step 19 . If frequency reading is not 2-20 Hz, go to next step.
Turn ignition on. Using DVOM, check voltage on affected ignition control circuit. If voltage reading is greater than one volt, go to step 18 . If voltage reading is not greater than one volt, go to next step.
Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of ignition control circuit from PCM harness connector to ignition control module harness connector. If DVOM reads 5 ohms or less, go to next step. If DVOM does not read 5 ohms or less, go to step 16 .
Check continuity between ignition control circuit and ground. If DVOM reads 5 ohms or less, go to step 17 . If DVOM does not read 5 ohms or less, go to step 23 .
Check for short to ground in ignition control module ignition feed circuit. Repair as necessary. After repairs, go to step 25 . If circuit is okay, go to step 21 .
Repair open in ignition control module ignition feed circuit. After repairs, go to step 25 .
Repair open in ignition control module ground. After repairs, go to step 25 .
Repair open/high resistance in ignition control module reference low circuit. After repairs, go to step 25 .
Repair open/high resistance in ignition control circuit. After repairs, go to step 25 .
Repair ignition control circuit for short to ground. After repairs, go to step 25 .
Repair ignition control circuit for short to voltage. After repairs, go to step 25 .
Turn ignition off. Using DVOM, check continuity between affected ignition control circuit and all other IC circuit. If continuity exists, go to next step. If continuity does not exist, go to step 21 .
Repair ignition control circuit that are shorted together. After repairs, go to step 25 .
Check for poor connections/terminals at ignition control module harness connector. Repair as necessary. After repairs, go to step 25 . If connections or terminals are okay, go to next step.
Remove ignition control module from coil assembly. Reconnect ignition control module harness connector. Connect Ignition Noid Light (J-43298) to module. Crank engine and observe noid light. If noid light flashes for all 3 cylinders, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If noid light does not flash for all 3 cylinders, go to next step.
Replace ignition control module. After replacing module, go to next step.
Check for poor connections/terminals at PCM harness connector. Repair or replace as necessary. After repairs, go to step 26 . If connections and terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Using scan tool, read and record FAILURE RECORDS data for this DTC. Clear DTCs. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, go to next step.
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are set, diagnose affected DTCs.

DTC P1370: IGNITION CONTROL (IC) MODULE 4X REFERENCE CIRCUIT TOO MANY PULSES (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks for too many 4X reference pulses between cam pulses. PCM checks to see if there are 48 24X reference pulses between cam pulses, and if there are, the PCM assumes it is receiving valid cam pulses. Therefore, if PCM sees more than 8 4X reference pulses between cam pulses, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check for possible sources of Electromagnetic Interference (EMI), such as spark wires routed too close to IC module, high power transmitter operating in the vicinity or a battery charger causing EMI. Correct problem, if present. If EMI is not present, go to next step.
Clear DTC(s) and retest. If DTC P1370 resets, go to next step. If DTC does not reset, fault is not present.
Check fuel control circuit terminal contact IC module connector C4 and PCM harness connector C2. Repair as necessary. If terminal contacts are okay, go to next step.
Replace IC module.

DTC P1371: IGNITION CONTROL (IC) MODULE 4X REFERENCE CIRCUIT TOO FEW PULSES (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks for too few 4X reference pulses between cam pulses. PCM checks to see if there are 48 24X reference pulses between cam pulses, and if there are, the PCM assumes it is receiving valid cam pulses. Therefore, if PCM see less than 8 4X reference pulses between cam pulses, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC(s) P0322 or P1302 is also present. If DTCs are present, diagnose affected DTC(s) first. If DTCs are not present, go to next step.
Check for possible sources of Electromagnetic Interference (EMI), such as spark wires routed too close to IC module, high power transmitter operating in the vicinity or a battery charger causing EMI. Correct problem, if present. If EMI is not present, go to next step.
Clear DTC(s) and retest. If DTC P1371 resets, go to next step. If DTC does not reset, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check fuel control circuit terminal contact in IC module connector C4 and PCM harness connector C2. Check for possible open or short in fuel control signal circuit. Repair as necessary. If terminal contacts or circuits are okay, go to next step.
Replace IC module.

An intermittent short or open to ground in the fuel control circuit to the PCM may set DTC. Check terminals carefully.

DTC P1372: IGNITION CONTROL (IC) SYSTEM OCCASIONAL RESYNC (3.5L "W" BODY)

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

This DTC indicates that there is an intermittent problem with the relationship between CKP sensor "A" and "B". DTC will run when engine is cranking or running. DTC will set when PCM detects an intermittent loss of match between the 2 CKP sensor signals.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P0335 or P0385 is also set. If any of this DTC is set, go to appropriate DTC test. If DTC P0335 or P0385 is not set, go to next step.
Start engine. Using scan tool, select CKP SENSOR STATUS. If sensor status indicates TIME "A", diagnose using DTC P0385 test. If sensor status does not indicate TIME "A", go to next step.
If sensor status indicates TIME "B", diagnose using DTC P0335 test. If sensor status does not indicate TIME "B", go to next step.
Move/wiggle related harnesses and connectors while monitoring scan tool display. If sensor status changes to TIME "A", diagnose using DTC P0385 test. If sensor status does not change to TIME "A", go to next step.
If sensor status changed to TIME "B", diagnose using DTC P0335 test. If sensor status did not change to TIME "B", problem is intermittent.

DTC P1374: 3X REFERENCE CIRCUIT (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

Conditions required to set DTC are, engine running and PCM is receiving 24X reference signal pulses, ratio of 24X reference signal pulses to 3X reference signal pulses received by PCM does not equal 8 and ratio of 24X reference signal pulses to camshaft reference signal pulses received by PCM equals 48.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see appropriate BASIC DIAGNOSTIC PROCEDURES article.
Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, go to next step. If scan tool does not display that this DTC FAILED THIS IGN, go to «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Install Injector Test Light (J-34730-2A) to any injector harness connector. Turn ignition on. Using a test light connected to ground, repeatedly touch test light lead to 3X reference signal circuit while observing injector test light. If injector test light blinks/flashes, go to step 8 . If injector test light does not flash, go to next step.
Turn ignition off. Disconnect PCM connector. Check 3X reference signal circuit for open or short to ground. If problem is found, go to step 11 . If no problem is found, go to next step.
Check for faulty 3X reference signal circuit connection at PCM. If connection is faulty, repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. If a problem is found, repair as necessary. After repairs, go to step 11 . If no problem is found, go to step 10 .
Check for faulty connections at ICM. If faulty connection is found, repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
Replace ICM. After replacing ICM, go to step 11 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.

Check for faulty connections or damaged harness. Observe a voltmeter connected to 3X reference circuit at PCM harness connector while moving all related harnesses and connectors. A change in voltage indicates fault location.

Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness.

DTC P1374: 3X REFERENCE CIRCUIT (3.8L "C", "F", "G", "H" & "W" BODIES)

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

3X reference circuit is produced by Ignition Control Module (ICM). PCM uses 3X reference signal pulses to calculate engine speed (RPM) and crankshaft position at engine speed greater than 1200 RPM. PCM uses pulses on this circuit to initiate injector pulses. If PCM receives incorrect number of pulses on 3X reference circuit, DTC will set. Conditions for setting DTC are: ratio of 18X reference signal pulses to CAM signal pulses received by the PCM equals 36:1, ratio of 18X reference pulses to 3X reference pulses received by the PCM does not equal 6:1, and conditions are present for greater than 10 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Attempt to start engine. If engine starts and runs, go to next step. If engine does not start and run, see appropriate BASIC DIAGNOSTIC PROCEDURES article.
Using scan tool, read and record FAILS RECORD DATA. Operate vehicle within conditions noted in FAILED RECORDS DATA. Read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, go to next step. If scan tool does not display that this DTC FAILED THIS IGN, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Connect a test light to any injector harness connector. Turn ignition on. Connect repeatedly touch test light lead to 3X reference signal circuit while observing test light. If test light blinks, go to step 8 . If test light does not flash, go to next step.
Turn ignition off. Disconnect PCM. Check 3X reference signal circuit for open or short to ground. If a problem is found, go to step 11 . If no problem is found, go to next step.
Check for faulty 3X reference signal circuit connection at PCM. Repair as necessary. After repairs, go to step 11 . If connection is okay, go to next step.
Check for incorrect harness routing near secondary ignition components, ignition coil arcing to wiring harness or ICM. Check ignition coils for cracks, carbon tracking or other signs of damage. Check for secondary ignition wire(s) arcing to wiring harness. Repair as necessary. After repairs, go to step 11 . If no problem is found, go to step 10 .
Check for faulty connections at ICM. Repair as necessary. After repairs, go to step 11 . If connections are okay, go to next step.
Replace ICM. After replacing module, go to step 11 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
Read and record FAILURE RECORDS data for this DTC. Operate vehicle within conditions noted in FAILURE RECORDS data. Using scan tool, read SPECIFIC DTC. If scan tool displays that this DTC FAILED THIS IGN, return to step 2 . If scan tool does not display that this DTC FAILED THIS IGN, repair is complete.

DTC P1375: IGNITION CONTROL (IC) MODULE 24X REFERENCE CIRCUIT HIGH VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks for 24X signal at a logic high condition. The fault could be induced by the failure of either crankshaft position "A" or "B" sensor input signal to the IC module. Under such a condition, the IC module would force the 24X signal high. This DTC will also set if the 24X signal is shorted to voltage externally. If either condition is met DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, check if DTC P1376 is also present. If DTC P1376 is present, diagnose DTC first. If DTC P1376 is not present, go to next step.
Turn ignition off. Disconnect IC module harness connector C1. Using DVOM, check resistance between IC module harness connector terminals "A" and "B". If resistance is 800-1600 ohms, go to next step. If resistance is not as specified, go to step 11 .
Check resistance between IC module harness connector terminals "E" and "F". If resistance is 800-1600 ohms, go to next step. If resistance is not as specified, go to step 14 .
Check resistance between ground and IC module harness connector C1, terminals "A", then "B", then "E" and then "F". If resistance is less than 1000 ohms at each terminal, go to step 17 . If resistance is not less than 1000 ohms at each terminal, go to next step.
Disconnect IC module harness connector C3. Set DVOM to PEAK MIN/MAX 4-volt scale, one ms sampling rate. Check the MAX DC voltage across IC module harness connector C1 terminals "A" and "B". Crank engine for 10 seconds. If voltage reading is greater than.25 volt while cranking engine, go to next step. If voltage reading is not greater than.25 volt while cranking engine, go to step 19 .
Check MAX DC voltage across IC module harness connector C1 terminals "E" and "F". Crank engine for 10 seconds. If voltage reading is greater than.25 volt while cranking engine, go to next step. If voltage reading is not greater than.25 volt, go to step 20 .
Reconnect IC module harness connectors C1 and C3. Disconnect IC module harness connector C4. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C2. Turn ignition on. Check voltage between ground and PCM harness connector C2 terminal No. 5. If voltage reading is less than.4 volt, go to next step. If voltage reading is not less than specified, go to step 18 .
Turn ignition off. Disconnect IC module harness connector C2. Using 6-Pin IC Module Diagnostic Jumpers, jumper the following IC module connector C4 terminals to the following module terminals: C4 Terminal "A" To Module Pin "A" C4 Terminal "B" To Module Pin "B" C4 Terminal "C" To Module Pin "C" C4 Terminal "D" To Module Pin "D" C4 Terminal "E" To Module Pin "E" C4 Terminal "F" To Module Pin "F" Turn ignition on. Set DVOM to 400 mV AC scale and push the Hertz button. Start engine. Connect DVOM between jumper "A" and ground. If frequency reading is greater than zero Hertz, go to next step. If frequency reading is not greater than zero Hertz, go to step 25 .
Clear all DTC(s). Disconnect terminal "A" jumper only. Start engine. Using scan tool in DTC INFO mode, select FAIL THIS IGN function. If DTC P1323 is present, fault is not present. If DTC P1323 is not present, go to step 27 .
If resistance in step 3 was less than the range specified, go to next step. If resistance was greater than the specified range, go to step 27 .
Disconnect crank sensor "A" harness connector. Check resistance across crank sensor harness connector terminals "A" and "B". If resistance is less than 10,000 ohms, go to step 21 . If resistance is not less than 10,000 ohms, go to step 19 .
Disconnect crank sensor "A" harness connector. Jumper crank sensor harness connector terminals "A" and "B" together. Check resistance between PCM harness connector C1 terminals "A" and "B". If resistance is greater than 5 ohms, go to step 22 . If resistance is less than 5 ohms, go to step 19 .
If resistance was lower in step 4 than the range that was specified, go to next step. If resistance was greater than the range that was specified, go to step 16 .
Disconnect crank sensor "B" harness connector. Check resistance across crank sensor harness connector terminals "A" and "B". If resistance is less than 10,000 ohms, go to step 23 . If resistance is greater than 10,000 ohms, go to step 20 .
Disconnect crank sensor "B" harness connector. Jumper crank sensor harness connector terminals "A" and "B" together. Check resistance between IC module connector C1 terminals "E" and "F". If resistance is greater than 5 ohms, go to step 24 . If resistance is not greater than 5 ohms, go to step 20 .
Repair short to ground in circuit(s) that measured low in step 5 .
Repair short to voltage in 24X spark reference circuit between IC module and PCM.
Replace crank sensor "A".
Replace crank sensor "B".
Repair crank sensor "A" circuits that are shorted together.
Repair open in either crank sensor "A" circuits.
Repair crank sensor "B" circuits that are shorted together.
Repair open in either crank sensor "B" circuits.
Check terminal contact at IC module harness connector C1 terminals "A", "B", "E" or "F".
Replace IC module.
Check terminal contact at PCM harness connector terminal No. 5 (24X spark reference circuit). Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

DTC P1376: IGNITION GROUND CIRCUIT (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

PCM applies 2.5 volts on the reference low circuit to the IC module. Reference low voltage to the PCM represents the voltage difference between reference low and the PCM power ground. This ensures that the PCM and IC module signals all have the same ground reference. If the reference low input voltage goes too high or low, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, select FAILURE REC. in DTC mode. Note REF VOLTS LOW display when this DTC set. If voltage reading is 1.4 volts or greater, go to next step. If voltage reading is less than 1.4 volts, go to step 8 .
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C2. Disconnect IC module harness connector C4. Turn ignition on. Using scan tool, check voltage between ground and reference low circuit at PCM harness connector C2. If voltage reading is greater than 0.1 volt, go to step 9 . If voltage reading is not greater than 0.1 volt, go to next step.
Check resistance of reference low circuit between IC module harness connector and PCM harness connector terminals. If resistance is 5 ohms or greater, go to step 10 . If resistance is less than 5 ohms, go to next step.
Turn ignition on. Check voltage to ground at reference low circuit at IC module harness connector C4. If voltage reading is 0.1 volt or greater, go to next step. If voltage reading is not 0.1 volt or greater, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect IC module harness connector C3. Check resistance to ground at IC module harness connector C3 terminal "A" (ground circuit). If resistance is 5 ohms or greater, go to step 11 . If resistance is not 5 ohms or greater, go to next step.
Check terminal contact at IC module and PCM harness connectors. Check PCM and IC module ground connections. Repair as necessary. Reconnect all harness connectors. Clear this DTC. Start engine. If DTC resets, go to step 13 . If DTC does not reset, fault is not present.
Turn ignition off. Disconnect both PCM harness connectors. Using DVOM, check resistance between ground and PCM ground circuits in PCM terminal. If resistance is greater than 5 ohms in any of the terminals, go to step 12 . If resistance is not greater than 5 ohms in any of the terminals, check PCM grounds.
Repair short to voltage in reference low circuit.
Repair open in reference low circuit.
Repair open in ground circuit to IC module.
Repair open in circuits that had high resistance.
Replace IC module.

This DTC may set due to an improperly installed PCM, causing PCM not to be electrically isolated from body ground.

DTC P1377: IGNITION CONTROL (IC) MODULE CAM PULSE TO 4X REFERENCE PULSE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks to see if there are 8 4X reference pulses between CAM signals. Do not attempt diagnosis or repair unless vehicle is experiencing driveability problems associated with this DTC.

DTC will set when the number of 4X reference pulses during 2 CAM pulse period is not 16 at least 2 times in a row.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If any other DTCs are present, diagnose affected DTC(s) first. If no other DTCs are present, go to next step.
If this DTC is set along with a driveability complaint, go to next step. If DTC is not set along with a driveability complaint, fault is not present, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
This DTC will set when are too many or too few cam or 4X pulses. Check for Electromagnetic Interference (EMI) being induced in the fuel control circuit, cam signal circuit or camshaft position sensor circuits by improper spark plug wire routing or high power transmitter operating in the vicinity. Correct any causes of EMI. If EMI is not present, go to next step.
Check for intermittent short to ground, circuit shorted together or open in fuel control circuit, cam signal circuit or camshaft position sensor circuits. Repair as necessary. If circuits are okay, go to next step.
Check terminal contacts at camshaft position sensor terminals. Repair as necessary. If terminal contacts are okay, go to next step.
Check terminal contact at camshaft position sensor to IC module. Check terminal contact at fuel control circuit and cam signal circuit to PCM. Repair as necessary. If terminal contacts are okay, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

Since this DTC can set under normal conditions, no diagnosis should be performed unless a driveability complaint is present. This DTC may also set if all 4 camshafts are off by one tooth (10 degrees BTDC), causing a severe driveability problem.

This DTC will set per requests from the ABS controller. If ABS controller detects faults in the ABS warning light circuit, traction active warning light, brake warning light circuit or detects that the brake switch is stuck, or communication with the PCM is closed or lost, it will command PCM to illuminate SERVICE light.

If DTCs are present, diagnose using ABS diagnostic tests. See appropriate ANTI-LOCK article in BRAKES.

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (2.2L & 2.4L "J" BODY & 2.2L "S" SERIES)

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

PCM detects engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when vehicle is operated over rough surfaces. The ABS system can detect when vehicle is on rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor.

The Electronic Brake Control Module (EBCM) sends information to the PCM through the Class II serial data line. PCM then uses this information in order to determine if crankshaft variations are being caused by actual misfire or from being driven on a rough road surface.

Whenever ABS is found to be malfunctioning, PCM will still continue to detect misfire. However, if misfire DTC is set, this DTC will also set, indicating that rough road surface data was not usable during misfire detection due to ABS malfunction.

DTC will set when DTCs P0300-P0304 is not set, vehicle speed is greater than one MPH, MAP is less than 99 kPa, engine speed is less than 3400 RPM and an ABS DTC is set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, check for ABS DTCs. If any ABS DTCs are set, go to next step. If no ABS DTCs are set, go to step 4 .
Repair ABS system as necessary. See appropriate ANTI-LOCK article in BRAKES.
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. If misfire DTC set, go to next step. If misfire DTC did not set, go to step 9 .
If DTC P1380 also set, go to next step. If DTC P1380 did not set, go to step 7 .
If ABS DTC is also set, go to step 3 . If ABS DTC is not set, go to step 8 .
Repair condition causing misfire as necessary. After repairs, go to step 9 .
Replace PCM. Program replacement PCM using required equipment. After repair is completed, go to next step.
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 .
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, no problem is indicated at this time.

Setting of this DTC indicates that a misfire was detected and that the PCM could not determine if fault was a true misfire or due to operating vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check Electronic Brake Control Module (EBCM) for poor connections at Class II serial data terminals.

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

PCM receives rough road information from EBCM/EBTCM on the serial data circuit. PCM uses this information to enhance the misfire diagnostic by distinguishing crankshaft speed variations caused by driving on rough road surfaces from variations caused by true misfires. EBCM/EBTCM transmits rough road information based on inputs from wheel speed sensors. If EBCM/EBTCM detects a condition which will allow it to properly identify rough road situations while a misfire condition is being detected by the PCM, DTC will set.

Conditions for setting DTC are: engine load is less than 87 percent, engine speed is less than 5000 RPM, vehicle speed is greater than 10 MPH, misfire DTC is occurring and requesting MIL to be illuminated and PCM has detected an EBCM/EBTCM rough road sensing error.

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, diagnose ABS/TCS system. See appropriate ANTI-LOCK article in BRAKES.

If this DTC is set, it indicates that the ABS/TCS system has detected a malfunction which will not allow the EBCM/EBTCM to transmit correct rough data to PCM. Diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES.

DTC P1380: EBTCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.5L "W" BODY)

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

Conditions for running the DTC are, engine load less than 87 percent, engine speed less than 5000 RPM, vehicle speed greater than 10 MPH, and a misfire DTC is occurring and requesting MIL to be illuminated. DTC will set when, PCM has detected an EBCM/EBTCM rough road sensing error.

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, diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES.

DTC P1380: EBTCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.8L "C", "F", "G", "H" & "W" BODIES)

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

This DTC is used to determine when the EBCM has lost the ability to provide rough road data to the PCM for misfire detection. When the PCM sees that this condition is present, through the serial data, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, select DTC INFO and note if this DTC has failed this ignition cycle. If DTC failed, diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES. If DTC did fail this ignition, go to next step.

If this DTC is set, it indicates that the ABS system has detected a malfunction which will not allow the EBCM to transmit correct rough road data to PCM.

DTC P1380: MISFIRE DETECTED - ROUGH ROAD DATA NOT AVAILABLE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This DTC is used to determine when the EBTCM has lost the ability to provide rough road data to the PCM for misfire detection (DTC P0300). DTC will set, when the PCM sees that this condition is present through the serial data for 1.6 seconds out of the last 2 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, select DTC INFO and note if this DTC has failed this ignition cycle. If DTC failed, diagnose EBTCM system. See appropriate ANTI-LOCK article in BRAKES. If DTC did fail this ignition, go to next step.
Check EBTCM system for any history ABS/TCS DTC(s) or system problems. If any other DTC(s) or problems are noted, diagnose EBTCM system. See appropriate ANTI-LOCK article in BRAKES. If no other DTCs are present, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

If this DTC is set along DTC P0300, it may represent an invalid misfire due to loss of rough road data. Several ABS system problems could cause a loss of rough road indication from EBTCM. All ABS/TCS system problems and DTC(s) should be corrected first, then duplicate the conditions under which DTC P1380 set and see if problem reoccurs.

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

This test determines if EBCM has lost the ability to provide rough road data to the VCM for misfire detection (DTC P0300). DTC will set when VCM determines that the ABS system is unable to detect a rough road condition.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Disconnect VCM and EBCM harness connectors. Check for open in serial data circuit between EBCM and VCM. If circuit is open, go to next step. If circuit is okay, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (4.3L, 5.0L, 5.7L & 7.4L "C", "G" & "K" SERIES)

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

This diagnostic determines if Electronic Brake Control Module (EBCM) has lost the ability to provide rough road data to the VCM for misfire detection (DTC P0300). DTC will set when VCM is unable to detect a rough road condition.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect VCM and EBCM harness connectors. Using DVOM, check for open in serial data circuit between VCM and EBCM. If a problem is found, go to next step. If no problem is found, see appropriate ANTI-LOCK article in BRAKES.
Repair as necessary. After repairs, go to next step.
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, DTC is intermittent.
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction. DTC will set when ABS system malfunction exists, preventing PCM from receiving rough road detection data.

Note. ABS system must be diagnosed/serviced before diagnosing misfire. Actual engine misfire may or may not exist.

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, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles occurred since diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction. DTC will set when ABS system malfunction exists preventing PCM from receiving rough road detection data.

Note. ABS system must be diagnosed/serviced before diagnosing misfire. Actual engine misfire may or may not exist.

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, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.

The ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by the wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to the PCM via the serial data (UART). PCM can then take the rough road into account when calculating misfire. Even if the ABS is malfunctioning and cannot detect rough roads, the misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC P1380 will also set indicating that rough road data was not available during the misfire calculation due to ABS system malfunction.

Conditions for setting this DTC are, DTC P0300-P0304 not set, vehicle speed greater than one MPH, engine speed is less than 3406 RPM and PCM received no ABS information for 2.5 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, attempt to display ABS data. If ABS data can be displayed, go to next step. If ABS data cannot be displayed, go to step 4 .
Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. 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. If a misfire DTC set, go to step 5 . If a misfire DTC did not set, go to step 9 .
Repair condition causing ABS data not to be displayed. See appropriate ANTI-LOCK article in BRAKES. After repairs, go to step 3 .
If DTC P1381 also set, go to next step. If DTC P1381 did not set, go to step 7 .
If ABS data can be displayed, go to step 8 . If ABS data cannot be displayed, go to step 4 .
Repair condition causing misfire as necessary. After repair is completed, go to step 9 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
If any other DTCs are set, diagnose DTCs as necessary. If no other DTCs are set, system is okay.

DTC P1381: MISFIRE DETECTED-NO EBCM/PCM SERIAL DATA (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

PCM receives rough road information from the EBCM/EBTCM on the Class II serial data circuit. PCM detects engine misfire by detecting variations in crankshaft deceleration between firing strokes. For accurate detection of engine misfire, PCM must be able to distinguish between crankshaft deceleration caused by actual misfire or deceleration caused by rough road conditions.

DTC will set when PCM is detecting a loss of communication with EBCM/EBTCM for at least 5 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, attempt to display ABS data. If ABS data can be displayed, go to next step. If ABS data cannot be displayed, go to step 4 .
Check serial data circuit for an open or poor connection between PCM and EBCM. Repair as necessary. After repairs, go to step 7 . If circuit is okay, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect EBCM. Turn ignition on. Using DVOM, check voltage between ground and serial data circuit terminal at Electronic Brake Control Module (EBCM) connector. If voltage reading is 1-5 volts, go to next step. If voltage reading is not 1-5 volts, go to step 6 .
Check for poor terminal connections at EBCM connector. Repair as necessary. After repairs, go to step 7 . If connections are okay, go to next step.
Check for an open or short to ground in serial data circuit. Repair as necessary. After repair is completed, go to next step. If circuit is okay, check ABS system. See appropriate ANTI-LOCK article in BRAKES.
Using scan tool, select CLEAR INFO or CLEAR DTCs function to clear DTCs. 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. Monitor SPECIFIC DTC info for this DTC until this DTC test runs. If scan tool indicates FAILED THIS IGN, repeat step 2 . If scan tool does not indicate FAILED THIS IGN, repair is complete.

Setting of this DTC indicates that a misfire was detected and that the PCM could not determine if fault was a true misfire or due to operating vehicle on a rough surface. A misfire can be a true misfire with or without setting this DTC. Check PCM or Electronic Brake Control Module (EBCM) for poor connections.

DTC P1381: MISFIRE DETECTED-NO EBTCM/PCM SRI DATA (3.5L "W" BODY)

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

Conditions for running the DTC are, engine load less than 87 percent, engine speed less than 5000 RPM, vehicle speed greater than 10 MPH, and a misfire DTC is occurring and requesting MIL to be illuminated. DTC will set when, PCM is detecting a loss of communication with the EBCM/EBTCM for at least 10 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, select CHASSIS DIAGNOSTICS. Attempt to display ABS data on scan tool. If ABS data can be displayed, go to next step. If ABS data cannot be displayed, diagnose ABS system. See appropriate ANTI-LOCK article in BRAKES.
Check serial data circuit for open or poor connection between PCM and EBTCM. Repair as necessary. If circuit or connection is okay, fault is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

DTC P1381: MISFIRE DETECTED-NO EBCM/PCM SERIAL DATA (3.8L "C", "F", G", "H" & "W" BODIES)

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

Electronic Brake Control Module (EBCM) transmits rough road information based on wheel acceleration/deceleration data supplied by the wheel speed sensors. If ABS system detects rough road above a predetermined threshold, information is sent to PCM through serial data circuit. Condition for setting DTC is, PCM is detecting a loss of communications with EBCM/EBTCM for at least 10 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS DATA. If ABS DATA is displayed, go to next step. If ABS DATA is not displayed, go to step 4 .
Check serial data circuit for open or faulty connection between EBCM and PCM. Repair as necessary. If circuit or connection is okay, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect EBCM harness connector. Turn ignition on. Using a DVOM, check voltage on EBCM harness connector serial data circuit. If voltage reading is 1-5 volts, go to next step. If voltage reading is not 1-5 volts, go to step 6 .
Check for faulty connection at EBCM. Repair as necessary. After repairs, go to step 7 . If connection is okay, go to next step.
Check for open serial data circuit to EBCM. Repair as necessary. After repairs, go to next step. If circuit is okay, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.
Turn ignition on. Using scan tool, select CHASSIS APPLICATION and attempt to display ABS DATA. If ABS DATA is displayed, repair is complete. If ABS DATA is not displayed, return to step 4 .

Check for faulty connections or damaged harness. If connections and harness appear okay, observe ABS DATA on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

DTC P1381: MISFIRE DETECTED-NO EBTCM/PCM SERIAL DATA (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks for the absence of serial data from the EBTCM. This data is needed for misfire diagnosis (DTC P0300), once data is received from the EBTCM. DTC will set if the serial data is lost from the EBTCM for 1.6 seconds out of the last 2 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, select DTC INFO and note if this DTC has failed this ignition cycle. If this DTC failed, diagnose EBTCM system. See appropriate ANTI-LOCK article in BRAKES. If DTC has not failed this ignition cycle, go to next step.
Check EBTCM system for any history ABS/TCS DTC(s) or system problems. If any DTC(s) or problems are noted, diagnose EBTCM using. See appropriate ANTI-LOCK article in BRAKES. If no DTC(s) or problems are noted, fault is not present.

If this DTC is set along with DTC P0300, it may represent an invalid misfire due to a loss of rough road data.

DTC P1381: MISFIRE DETECTED-NO EBCM/VCM SERIAL DATA (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

This test detects a loss of serial communication from Electronic Brake Control Module (EBCM) to VCM. This serial communication is essential to distinguish misfire from rough road condition. DTC will set when serial data malfunction is preventing the VCM from receiving rough road detection data.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Disconnect VCM and EBCM harness connectors. Check for open in serial data circuit between EBCM and VCM. If circuit is open, go to next step. If circuit is okay, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select Read and Record INFO, REVIEW INFO function. Check if any undiagnosed DTCs are displayed. Diagnose affected DTCs. If no additional DTCs are displayed, system is okay.

Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harness and connectors. A change in scan tool display indicates fault location.

DTC P1381: MISFIRE DETECTED-NO EBCM/VCM SERIAL DATA (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 diagnostic determines a serial data malfunction which could inhibit transfer of ABS rough road data to VCM. DTC will set when misfire DTC is active and requesting MIL is on and no rough road data is available from EBCM.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect VCM and EBCM harness connectors. Using DVOM, check for open in serial data circuit between VCM and EBCM. If a problem is found, go to next step. If no problem is found, see appropriate ANTI-LOCK article in BRAKES.
Repair as necessary. After repairs, go to next step.
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, DTC is intermittent.
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction. DTC will set when serial data malfunction exists, preventing PCM from receiving rough road detection data.

Note. Serial data must be serviced before diagnosing misfire. Actual engine misfire may or may not exist.

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, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

ABS system can detect if vehicle is on a rough road based on wheel acceleration/deceleration data supplied by wheel speed sensors. If ABS system detects rough road above a predetermined threshold, this information is sent to PCM via serial data. PCM can then take rough road into account when calculating misfire. Even if ABS is malfunctioning and cannot detect rough roads, misfire diagnostic will continue to run. However, if a misfire DTC is set, this additional DTC will also set indicating that rough road data was not available during misfire calculation due to ABS system malfunction. DTC will set when serial data malfunction exists preventing PCM from receiving rough road detection data and conditions is met for 20 seconds.

Note. Serial data must be serviced before diagnosing misfire. Actual engine misfire may or may not exist.

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, perform ABS system diagnosis. See appropriate ANTI-LOCK article in BRAKES.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

DTC P1404: EGR VALVE CLOSED POSITION ERROR (1.9L SATURN)

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

PCM directly controls the ground for the linear EGR valve when certain conditions have been met. PCM contains a diode feedback circuit which dissipates energy when the valve is cycled off. When PCM grounds the valve, a diagnostic feedback signal can determine is valve had actually moved. This DTC has been defined to monitor the feedback signal. This diagnostic will determine if the position feedback signal properly falls within the correct range under different valve operating conditions.

DTC will set when the actual closed value does not match the learned closed value within 20 seconds if RPM is less than 5000 and the actual versus learned value is greater than 0.2 volt, or RPM is greater than 5000 and the actual versus learned value is greater than 0.4 volt.

When PCM recognizes that the parameters for setting DTC P1404 have been set, the diagnostic software waits until the EGR cycles open 25 percent or greater, 3 times and then retest. If after 3 cycles, the actual versus learned values is not within the parameters, DTC will be stored and MIL will illuminate.

When this DTC sets, some EGR functions will be disabled for the duration of that ignition cycle. When repairs are complete, DTCs must be cleared to allow proper operation.

Note. If DTC P0404 or P0405 is present, diagnose P0404 or P0405 first. Do not clear DTCs until diagnosis is complete.

Install scan tool. Turn ignition on, engine off. Using scan tool, compare learned closed pintle position to actual pintle position voltage. If voltage differs, go to next step. If voltage is the same, go to step 3 .
Check for backed-out, damaged or loose terminal connections. Check for intermittent open in EGR valve harness connector terminals "C" and "D" circuits. Repair as necessary.
If voltage difference is greater than.15 volt, go to step 5 . If voltage difference is not greater than.15 volts, go to next step.
Using scan tool, locate DTC P1404 in Code Status. Road test vehicle to obtain a PASS or FAIL diagnostic. If a PASS is obtained, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If a FAIL is obtained, go to step 9 .
If voltage is greater than 1.5 volts and engine runs okay, go to next step. If voltage is greater than 1.5 volts and engine runs rough or stalls, disconnect EGR harness connector. If engine does not smooth out, go to next step. If engine smooths out, check for short to ground in circuit between PCM and EGR harness connector terminal "A". If circuit is okay, replace faulty PCM.
Disconnect EGR valve harness connector. If pintle voltage is now less than 1.5 volts, go to step 8 . If pintle voltage is not less than 1.5 volts, go to next step.
Turn ignition off. Disconnect PCM harness connector J2. Remove circuit from EGR harness connector terminal "C" at PCM harness connector. Reconnect PCM harness connector. Turn ignition on. Check voltage at disconnected terminal. If voltage reading is greater than.15 volt, repair short to ground in circuit. If voltage reading is not greater than.15 volt, replace PCM.
Using test light connected to battery voltage, probe EGR valve harness connector terminal "B". If test light illuminates, go to next step. If test light does not illuminate, check circuit for open or proper terminal connection. Repair as necessary. If circuit or terminals are okay, replace PCM.
Start engine. Using scan tool, command EGR valve to full open (100) and then back to closed position for 3 times. Drive vehicle to obtain a PASS or FAIL diagnosis. Drive vehicle at sufficient time and distance to obtain at least 4 or more EGR openings. If a PASS is obtained, go to next step. If a FAIL is obtained, go to step 11 .
Problem was likely debris in EGR pintle. Clean EGR valve. Clear DTCs and test drive vehicle.
Replace EGR valve. Check and clean EGR port for carbon or debris. Road test vehicle and verify diagnostic PASS.

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

Check for backed-out or damaged terminals, or for proper terminal connection. Check for stuck open EGR pintle. Check for open in circuit between EGR harness connector terminal "B" and PCM. Check for short to ground in circuit between EGR harness connector terminal "A" and PCM, which will cause severe rough idle and driveability complaint.

DTC P1404: EGR VALVE PINTLE STUCK OPEN (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 EGR valve pintle position input to ensure that valve responds properly to commands from the PCM. When ignition is turned on, PCM learns the EGR closed valve pintle position. PCM compares the learned EGR closed valve pintle position to the actual position when EGR valve is commanded closed. If actual EGR position indicates that EGR valve is still open when PCM is commanding EGR closed, DTC will set.

Conditions for setting DTC are: there is no CKP, ECT, IAT, MAF, MAP, TP or VSS DTC set, no misfire, idle speed, fuel injector related DTCs set, system voltage 10-16 volts, EGR feedback is.2 volt greater than EGR closed valve pintle position when desired EGR position is commanded to zero percent and conditions present for longer than 20 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, observe actual EGR position. If actual EGR position is zero percent, go to next step. If actual EGR position is not zero percent, go to step 5 .
Turn ignition on, engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired EGR position remains close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position, go to step 6 .
Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until this DTC test runs. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. Observe actual EGR position on scan tool. If actual EGR position is at zero percent, go to next step. If actual EGR position is not at zero percent, go to step 7 .
Using test light connected to battery voltage, probe test light to EGR pintle position sensor ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between ground and EGR pintle position signal circuit. If voltage reading is zero volts, go to step 12 . If voltage reading is not zero volts, go to step 11 .
Check EGR pintle position sensor ground circuit for an open between EGR and EGR valve. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace EGR valve. If EGR showed signs of excessive heat, check for restricted exhaust. Exhaust restriction may be caused by faulty injector, grounded injector circuit or faulty PCM. Repair as necessary. Also, check for contaminated oil. After replacing EGR valve, go to step 15 .
Locate and repair short to voltage in EGR pintle position signal circuit. After repairs, go to step 15 .
Check EGR position signal circuit for short to 5-volt reference circuit or short to control circuit. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 14 .
Check circuits related to EGR valve for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
Using scan tool, select CAPTURED INFO feature. If any undiagnosed DTCs are displayed, go to affected DTC test.

Check for excessive deposits on EGR valve pintle or seat, causing EGR valve to stick. Check for poor connections at EGR and PCM connector. Check for faulty terminal connections or damaged harness.

DTC P1404: EGR VALVE PINTLE STUCK OPEN (3.5L "W" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, observe actual EGR position. If actual EGR position is zero percent, go to next step. If actual EGR position is not zero percent, go to step 5 .
Turn ignition on, engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired EGR position remains close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position, go to step 6 .
Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until DTC P1404 test runs. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. Observe actual EGR position on scan tool. If actual EGR position is at zero percent, go to next step. If actual EGR position is not at zero percent, go to step 7 .
Using test light connected to battery voltage, probe test light to EGR pintle position sensor ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between ground and EGR pintle position signal circuit. If voltage reading is zero volts, go to step 12 . If voltage reading is not zero volts, go to step 11 .
Check EGR pintle position sensor ground circuit for an open between EGR and EGR valve. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace EGR valve. If EGR valve showed signs of excessive heat, check for restricted exhaust. Exhaust restriction may be caused by faulty injector, grounded injector circuit or faulty PCM. Repair as necessary. Also, check for contaminated oil. After replacing EGR valve, go to step 15 .
Locate and repair short to voltage in EGR pintle position signal circuit. After repairs, go to step 15 .
Check EGR position signal circuit for short to 5-volt reference circuit or short to control circuit. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 14 .
Check circuits related to EGR valve for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
Using scan tool, select CAPTURED INFO feature. If any undiagnosed DTCs are displayed, go to affected DTC test.

Check for excessive deposits on EGR valve pintle or seat, causing EGR valve to stick. Check for poor connections at EGR and PCM connector. Check for faulty terminal connections or damaged harness.

DTC P1404: EGR VALVE PINTLE STUCK OPEN OR STUCK CLOSED (3.8L "C", "G", "H" & "W" BODIES)

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

Conditions for setting DTC are: no CKP, ECT, IAT, MAF, MAP, TP or VSS DTC set, no misfire, idle speed, fuel injector related DTCs set, system voltage 10-16 volts, EGR feedback is.2 volt or greater than EGR closed valve pintle position when desired EGR position is commanded to zero percent and conditions are present for longer than 20 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, observe actual EGR position. If actual EGR position is zero percent, go to next step. If actual EGR position is not zero percent, go to step 5 .
Turn ignition on, engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired EGR position remains close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position, go to step 6 .
Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until DTC P1404 test runs. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. Observe actual EGR position on scan tool. If actual EGR position is at zero percent, go to next step. If actual EGR position is not at zero percent, go to step 7 .
Using test light connected to battery voltage, probe test light to EGR pintle position sensor ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between ground and EGR pintle position signal circuit. If voltage reading is zero volts, go to step 12 . If voltage reading is not zero volts, go to step 11 .
Check EGR pintle position sensor ground circuit for an open between EGR and EGR valve. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace EGR valve. If EGR showed signs of excessive heat, check for restricted exhaust. Exhaust restriction may be caused by faulty injector, grounded injector circuit or faulty PCM. Repair as necessary. Also, check for contaminated oil. After replacing EGR valve, go to step 15 .
Locate and repair short to voltage in EGR pintle position signal circuit. After repairs, go to step 15 .
Check EGR position signal circuit for short to 5-volt reference circuit or short to control circuit. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 14 .
Check circuits related to EGR valve for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .

Check for excessive deposits on EGR valve pintle or seat, causing EGR valve to stick. Check for poor connections at EGR and PCM connector. Check for faulty terminal connections or damaged harness.

DTC P1404: EGR VALVE CLOSED PINTLE POSITION (3.8L "F" BODY)

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

Condition for setting DTC is when EGR feedback is 0.2 volt greater that the EGR closed valve pintle position when the desired EGR position is commanded to zero percent and condition is present for about 20 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, observe actual EGR position. If actual EGR position is zero percent, go to next step. If actual EGR position is not zero percent, go to step 5 .
Turn ignition on, engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired EGR position remains close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position, go to step 6 .
Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until DTC test runs. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. Observe actual EGR position on scan tool. If actual EGR position is at zero percent, go to next step. If actual EGR position is not at zero percent, go to step 7 .
Using test light connected to battery voltage, probe test light to EGR pintle position sensor ground circuit. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 8 .
Turn ignition off. Disconnect PCM harness connector. Turn ignition on, engine off. Check voltage between ground and EGR pintle position signal circuit. If voltage reading is zero volts, go to step 12 . If voltage reading is not zero volts, go to step 11 .
Check EGR pintle position sensor ground circuit for an open between EGR and EGR valve. Repair as necessary. After repairs, go to step 15 . If circuit is okay, go to step 13 .
Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace EGR valve. If EGR showed signs of excessive heat, check for restricted exhaust. Exhaust restriction may be caused by faulty injector, grounded injector circuit or faulty PCM. Repair as necessary. Also, check for contaminated oil. After replacing EGR valve, go to step 15 .
Locate and repair short to voltage in EGR pintle position signal circuit. After repairs, go to step 15 .
Check EGR position signal circuit for short to 5-volt reference circuit or short to control circuit. Repair as necessary. After repairs, go to step 15 . If circuits are okay, go to step 14 .
Check circuits related to EGR valve for poor terminal connections at PCM. Repair as necessary. After repairs, go to step 15 . If connections are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 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 .

Check for excessive deposits on EGR valve pintle or seat, causing EGR valve to stick. Check for poor connections at EGR and PCM connector. Check for faulty terminal connections or damaged harness.

DTC P1404: EGR VALVE CLOSED POSITION PERFORMANCE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

This test checks for malfunction in the circuitry and hardware of the linear EGR valve. This test is used to indicate a stuck open EGR valve. When EGR valve desired position is zero (closed) the current (closed) EGR pintle position is subtracted from the learned low EGR pintle position.

When the open valve condition is indicated, this test waits for EGR to be opened enough so a possible restriction (usually carbon deposits) could possibly clear. When EGR valve desired position returns to zero (closed), this test rechecks the difference between the closed and learned low pintle positions and if significant difference is still there, a timer is incremented. When the time limit has been reached, a failure is indicated and this DTC sets.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, check EGR pintle position. If scan tool displays 0.18-2.06 volts, go to next step. If scan tool does not display 0.18-2.06 volts, go to step 8 .
Using scan tool, select OUTPUT TESTS for EGR. Command EGR to zero percent. Check EGR pintle position display. If scan tool displays 1 volt or less, go to next step. If scan tool does not display 1 volt or less, go to step 20 .
Command EGR to 50 percent. Check EGR pintle position display. If scan tool displays 2-3 volts, go to next step. If scan tool does not display 2-3 volts, go to step 25 .
Command EGR to 100 percent. Check EGR pintle position display. If scan tool displays 4 volts, go to next step. If scan tool does not display 4 volts, go to step 22 .
Select FREEZE FRAME or FAILURE REC. Check EGR pintle position when DTC was set. If voltage reading is.18 volt or greater, go to next step. If voltage reading is not.18 volt or greater, go to step 21 .
If voltage reading is 5 volts or greater, go to step 24 . If voltage reading is not 5 volts or greater, go to step 21 .
If voltage reading is.18 volt or less, go to next step. If voltage reading is not.18 volt or less, go to step 16 .
Exit OUTPUT TESTS. Using scan tool, check EGR pintle position. Disconnect EGR valve harness connector. Jumper EGR harness connector terminals "C" and "D". If voltage reading is.18 volts or less, go to next step. If voltage reading is not.18 volts or less, go to step 15 .
Using DVOM, check voltage between ground and jumper wire. If voltage reading is less than 4.5 volts, go to next step. If voltage reading is not less than 4.5 volts, go to step 26 .
Remove jumper wire. Check voltage between ground and EGR harness connector terminal "D". If voltage reading less than 4.5 volts, go to next step. If voltage reading is not less than 4.5 volts, go to step 27 .
Using scan tool, store fluid life data. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector. Disconnect TP sensor harness connector. Check resistance between ground and EGR harness connector terminal "D". If resistance is greater than 10,000 ohms, go to next step. If resistance is not greater than 10,000 ohms, go to step 28 .
Check resistance between PCM harness connector terminal No. 62 and EGR harness connector terminal "D". If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, go to step 29 .
Check terminal contact at PCM harness connector C1 terminal No. 62. Repair as necessary. If terminal contact is okay, go to step 35 .
Check terminal contact at EGR harness connector. Repair as necessary. If terminal contact is okay, go to step 34 .
Exit OUTPUT TESTS. Using scan tool, check EGR pintle position. Disconnect EGR harness connector. If voltage reading is less than 2.06 volts, go to next step. If voltage reading is not less than 2.06 volts, go to step 30 .
Disconnect TP sensor and ECT sensor harness connectors. Using DVOM, check voltage between ground and EGR harness connector terminal "B". If voltage reading is 0.1 volt or less, go to next step. If voltage reading is not 0.1 volt or less, go to step 31 .
Check voltage between ground and EGR harness connector terminal "D". If voltage reading is 5.5 volts or less, go to next step. If voltage reading is not 5.5 volts or less, go to step 32 .
Store fluid life data. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector C1. Check resistance between PCM harness connector terminal No. 7 and EGR harness connector terminal "B". If resistance is less than 5 ohms, go to step 15 . If resistance is not less than 5 ohms, go to step 33 .
Check for poor terminal contact at EGR harness connector and PCM harness connector C1. Check for high resistance in EGR pintle position ground, sticky EGR valve. Check for intermittent short to ground in EGR position feedback circuit, the 5-volt reference circuit and the EGR pintle position ground circuit. Repair as necessary. If circuits are okay, fault is not present.
Check terminal contact at PCM and EGR harness connectors. Check for sticky EGR valve or debris in EGR system, causing EGR valve to stick. Repair as necessary. If repairs were not required, fault is not present.
Check for terminal contact at PCM and EGR harness connectors. Check for high resistance in EGR position feedback circuit 5-volt reference circuit. Check for a sticky EGR valve. Repair as necessary. If repairs were not required, fault is not present.
Check for intermittent opens or shorts to ground in 5-volt reference circuit and EGR position feedback circuit. Repair as necessary. If repairs were not required, fault is not present.
Check for intermittent open in EGR pintle position ground circuit. Check for intermittent short to voltage in EGR position feedback circuit, EGR pintle position ground circuit or the 5-volt reference circuit. The reference circuit short may be located on any of the PCM 5-volt reference circuit (i.e. TP sensor 5-volt reference). Repair as necessary. If repairs were not required, fault is not present.
Check for intermittent open or short in the ignition feed circuit and EGR valve control circuit. Check for a sticky EGR valve. Repair as necessary. If repairs were not required, fault is not present.
Repair open in EGR position feedback circuit.
Repair short to ground in EGR position feedback circuit.
Repair short to ground in 5-volt reference circuit. Short may be located on any of the PCM 5-volt reference circuits (i.e. TP sensor 5-volt reference).
Repair open in 5-volt reference circuit.
Repair short to voltage in EGR position feedback circuit.
Repair short to voltage in EGR pintle position ground circuit.
Repair short to voltage in 5-volt reference circuit.
Repair open in EGR pintle position ground circuit.
Replace EGR valve.
Replace PCM. Program replacement PCM using required equipment.

DTC P1404: EGR VALVE CLOSED PINTLE POSITION (4.3L "L", "M", "S" & "T" SERIES)

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

This test checks if EGR valve is stuck open. VCM determines that EGR is stuck open if actual EGR position and learned closed EGR position vary by greater than a predetermined value. VCM checks for a stuck valve when desired EGR position is at zero percent. VCM commands EGR valve to 100 percent during certain driving conditions in order to clear a possible restriction from EGR valve if VCM determines that valve is stuck open.

VCM rechecks for a stuck valve when desired EGR position returns to zero percent. A failure timer increments if the stuck EGR valve condition is still present. DTC will set when EGR pintle position voltage is.29 volt or greater with EGR valve commanded closed and condition exists for greater than 10 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Using scan tool, command EGR valve to 20, 50, 70 and 100 percent, then back to zero percent. If actual EGR position follows commanded EGR position, go to next step. If actual EGR position does not follow commanded EGR position, go to step 4 .
DTC is intermittent. Check if additional DTCs are set. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. If actual EGR position is about zero percent, go to step 6 . If actual EGR position is not about zero percent, go to next step.
Check EGR valve pintle position signal circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
Using DVOM, check voltage between ground and EGR 5-volt reference circuit terminal at harness connector. If voltage reading is about 5.2 volts, go to next step. If voltage reading is not about 5.2 volts, go to step 8 .
Using test light connected to ground, probe test light to EGR valve feed control circuit terminal at harness connector. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
Check EGR 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 .
Check EGR valve feed circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
Replace EGR valve. After replacing EGR valve, go to step 12 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 this DTC ran and passed, go to next step. If scan tool does not indicate that this DTC ran and passed, repeat step 2 .
Using scan tool, check if any other DTCs are set. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Moisture in exhaust system may cause EGR valve to freeze or stick in colder weather. After vehicle is brought into a warm shop for repairs, EGR valve warms up and the problem goes away. By watching ACTUAL EGR POSITION and DESIRED EGR POSITION on a cold vehicle with a scan tool, view FREEZE FRAME data to determine if DTC set when vehicle was cold by viewing ENGINE COOLANT TEMPERATURE and INTAKE AIR TEMPERATURE.

DTC P1404: EGR VALVE CLOSED PINTLE POSITION (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.

DTC will set when ECT is greater than 176°F (80°C) but less than 248°F (120°C), IAT is less than 212°F (100°C), desired EGR greater than 14 percent and difference between actual and learned EGR pintle position is greater than 0.2 volt.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Using scan tool, command EGR valve to 20, 50, 70 and 100 percent. If actual EGR position follows commanded EGR position, go to next step. If actual EGR position does not follow commanded EGR position, go to step 4 .
DTC is intermittent. Check if additional DTCs are set. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR harness connector. If actual EGR position is about zero percent, go to step 6 . If actual EGR position is not about zero percent, go to next step.
Check EGR valve signal circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
Using DVOM, check voltage between ground and EGR 5-volt reference circuit terminal at harness connector. If voltage reading is about 5.2 volts, go to next step. If voltage reading is not about 5.2 volts, go to step 8 .
Using test light connected to ground, probe test light to EGR valve feed control circuit terminal at harness connector. If test light illuminates, go to step 9 . If test light does not illuminate, go to step 10 .
Check EGR 5-volt reference circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
Check EGR control circuit for short to voltage. Repair as necessary. After repairs, go to step 12 . If circuit is okay, go to step 11 .
Replace EGR valve. After replacing EGR valve, go to step 12 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 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 .
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»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

DTC P1404: EGR VALVE PINTLE STUCK OPEN (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

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

This test checks if EGR valve is stuck open. PCM determines that EGR is stuck open if actual EGR position and learned closed EGR position vary by greater than a predetermined value. PCM checks for a stuck valve when desired EGR position is at zero percent. PCM commands EGR valve to 100 percent during certain driving conditions in order to clear a possible restriction from EGR valve if PCM determines that valve is stuck open.

PCM rechecks for a stuck valve when desired EGR position returns to zero percent. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when timer reaches a predetermined value or when actual closed EGR pintle position voltage is.29 volt greater than desired closed EGR pintle position voltage.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC INFORMATION option. If scan tool indicates that DTC P1635 failed in this ignition cycle, diagnose DTC P1635. If scan tool does not indicate that DTC P1635 failed in this ignition cycle, go to next step.
With engine at idle, observe idle quality. If idle quality is poor, go to next step. If idle quality is okay, go to step 5 .
Disconnect EGR harness connector. If idle quality returns to normal, go to step 13 . If idle quality does not return to normal, go to step 15 .
Turn ignition on, engine off. Using scan tool, observe EGR pintle position voltage. If EGR pintle position voltage is 0.14-1.07 volts, go to next step. If EGR pintle position voltage is not 0.14-1.07 volts, go to step 7 .
Turn ignition on, engine off. Select FREEZE FRAME and/or FAILURE RECORDS data for this DTC and record parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this diagnostic to run and as close to FREEZE FRAME/FAILURE RECORDS as possible. Select DTC option and SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR valve harness connector. Using scan tool, observe EGR pintle position voltage. If EGR position voltage is 0.14 volt, go to next step. If EGR position voltage is not 0.14 volt, go to step 10 .
Using test light connected to ground, probe test light to EGR pintle position ground circuit at harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
Check voltage between ground and 5-volt reference circuit at EGR harness connector. If voltage reading is greater than 5 volts, go to step 14 . If voltage reading is not greater than 5 volts, go to step 16 .
Turn ignition off. Disconnect PCM connector. Check for short in EGR signal circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to step 17 .
Check for open in EGR pintle position ground circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to next step.
Turn ignition off. Disconnect PCM harness connector. Check EGR pintle position ground circuit for good connection to PCM. Repair as necessary. After repairs, go to step 18 . If connection is okay, go to step 17 .
Disconnect PCM harness connector. Check for short to voltage in EGR 5-volt reference circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to step 17 .
Repair 5-volt reference circuit for short to voltage. After repairs, go to step 18 .
Remove EGR valve. Inspect and clean pintle. After cleaning EGR valve, go to step 18 . If debris was not found in EGR valve pintle, go to next step.
Replace EGR valve. After replacing EGR valve, go to step 18 .
Replace PCM. Program replacement PCM using required equipment.
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 .
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»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

DTC P1404: EGR VALVE PINTLE STUCK OPEN (5.7L "F" BODY)

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

PCM rechecks for a stuck valve when desired EGR position returns to zero percent. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when timer reaches a predetermined value and ignition voltage greater than 11.7 volts and actual EGR pintle position greater than 0.29 volt when valve is commanded closed.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine at idle. Using scan tool, monitor FAILED THIS IGNITION under DTC INFORMATION option. If scan tool indicates that DTC P1635 failed in this ignition cycle, diagnose DTC P1635. If scan tool does not indicate that DTC P1635 failed in this ignition cycle, go to next step.
With engine at idle, observe idle quality. If idle quality is poor, go to next step. If idle quality is okay, go to step 5 .
Disconnect EGR harness connector. If idle quality returns to normal, go to step 13 . If idle quality does not return to normal, go to step 15 .
Turn ignition on, engine off. Using scan tool, observe EGR pintle position voltage. If EGR pintle position voltage is 0.14-1.07 volts, go to next step. If EGR pintle position voltage is not 0.14-1.07 volts, go to step 7 .
Turn ignition on, engine off. Select FREEZE FRAME and/or FAILURE RECORDS data for this DTC and record parameters. Turn ignition off for 15 seconds. Start and operate vehicle within conditions required for this diagnostic to run and as close to FREEZE FRAME/FAILURE RECORDS as possible. Select DTC option and SPECIFIC DTC option, then enter this DTC. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect EGR valve harness connector. Using scan tool, observe EGR pintle position voltage. If EGR position voltage is 0.14 volt, go to next step. If EGR position voltage is not 0.14 volt, go to step 10 .
Using test light connected to ground, probe test light to EGR pintle position ground circuit at harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11 .
Check voltage between ground and 5-volt reference circuit at EGR harness connector. If voltage reading is greater than 5 volts, go to step 14 . If voltage reading is not greater than 5 volts, go to step 16 .
Turn ignition off. Disconnect PCM connector. Check for short in EGR signal circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to step 17 .
Check for open in EGR pintle position ground circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to next step.
Turn ignition off. Disconnect PCM harness connector. Check EGR pintle position ground circuit for good connection to PCM. Repair as necessary. After repairs, go to step 18 . If connection is okay, go to step 17 .
Disconnect PCM harness connector. Check for short to voltage in EGR 5-volt reference circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to step 17 .
Repair 5-volt reference circuit for short to voltage. After repairs, go to step 18 .
Remove EGR valve. Inspect and clean pintle. After cleaning EGR valve, go to step 18 . If debris was not found in EGR valve pintle, go to next step.
Replace EGR valve. After replacing EGR valve, go to step 18 .
Replace PCM. Program replacement PCM using required equipment.
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 .
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»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

DTC P1415: AIR SYSTEM BANK 1 (4.3L "C" & "K" SERIES)

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

A fused ignition voltage is supplied to AIR relay. PCM controls AIR pump by grounding AIR relay control circuit which energizes relay and supplies voltage to AIR pump clutch. When fuel system goes to closed loop, PCM opens ground to AIR control circuit.

DTC will set when HO2S voltage does not go less than 222 mV within 1.2 seconds and short term fuel trim does not go greater than a predetermined amount.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and operate engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature and in "closed-loop". Using scan tool, command AIR pump on. Observe Short Term Fuel Trim Bank 1. If scan tool indicates a change of 16 percent within 30 seconds, go to next step. If scan tool does not indicate a change of 16 percent within 30 seconds, go to step 4 .
DTC P1415 is intermittent. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect hose from check valve at left exhaust manifold. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to next step. If air does not flow from valve, go to step 7 .
Repair blockage or restrictions in AIR hose between check valve and each bank. If problem is found, go to step 8. If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for restrictions or leaks in bank 1 AIR hose between check valve and other branches. If problem is found, go to next step. If no problems were found, diagnose air injection system.
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness. Check for worn or loose AIR pump drive belt. Check for pinched, kinked or restricted AIR pipes, hoses or fittings.

The AIR pump is used to lower tailpipe emissions on start-up. VCM supplies ground to AIR pump relay to energize the AIR solenoid and pump. VCM will run a test using HO2S voltages to diagnose the AIR system. During this test, VCM will activate the AIR pump during "closed-loop" operation. When system is activated, VCM will monitor the HO2S voltages and short term fuel trim values for both engine banks. If AIR system is operating properly, HO2S voltages should go low and short term fuel trim should go high.

VCM checks the HO2S voltages return to above a rich threshold when AIR pump is disabled. If VCM determines that the HO2S voltages for both banks did not respond as expected during tests, DTC P0410 will set. If only one sensor responded, VCM will set either DTC P1415 or P1416 to indicate which bank the AIR system is inoperative.

DTC will set when HO2S voltage is not less than 222 mV for greater than 1.3 seconds or the short term fuel trim value changes to greater than 20 percent when secondary air injection pump is turned on and system is in "closed-loop".

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and run engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. If bank 1 short term fuel trim indicates a change of greater than 16 percent, go to next step. If bank 1 short term fuel trim does not indicate a change of greater than 16 percent, go to step 4 .
DTC is intermittent. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If any additional DTCs are set, go to applicable DTC test.
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect bank 1 AIR crossover hose from AIR valve. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to next step. If air does not flow from valve, go to step 7 .
Check for restrictions or leaks in bank 1 AIR pipe, hoses and fittings. If a problem is found, go to step 8 . If no problem is found, go to step 9 .
Repair leaks or restrictions in bank 1 AIR hose between check valve and each bank. After repairs, go to step 10 .
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Low AIR system volume may cause DTC P1415, P1416 or an intermittent complaint. Check for pinched, kinked or restricted AIR pipes, hoses or fitting. Check for obstructed or restricted AIR pump inlet. An intermittent may be caused by a poor connection, rubbed-through wire insulation or a broken wire inside insulation.

DTC P1415: AIR SYSTEM BANK 1 (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

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

DTC will set when HO2S voltage does not go less than 222 mV within 1.2 seconds and short term fuel trim does not go greater than a predetermined amount.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and operate engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. Observe Bank 1 Sensor 1 HO2S voltage as AIR pump is enabled. If HO2S voltage drops to less than 350 mV, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If HO2S voltage does not drop to less than 350 mV, go to next step.
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 7 . If no problems were found, go to next step.
Disconnect hose from check valve at left exhaust manifold. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to step 7 . If air does not flow from valve, go to next step.
Repair blockage or restrictions in AIR hose between check valve and each bank. After repairs, go to step 8 .
Repair as necessary. After repairs, go to step 8 .
Replace check valve. After replacing check valve, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1415: AIR SYSTEM BANK 1 (5.0L & 5.7L "C" & "K" SERIES)

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

A fused ignition voltage is supplied to AIR relay. VCM controls AIR pump by grounding AIR relay control circuit which energizes relay and supplies voltage to AIR pump clutch. When fuel system goes to closed loop, VCM opens ground to AIR control circuit.

DTC will set when the following conditions are present

AIR Passive Test Enable

No ECT, EVAP, HO2S, IAT, MAF, MAP or TP sensor DTCs set.
No misfire DTCs are set.
No fuel trim DTCs are set.
System voltage greater than 10 volts for greater than 3 seconds.
IAT greater than 32°F (0°C).
Engine run time greater than 3 seconds.

AIR Active Test Enable

AIR passive test failed.
No EVAP, HO2S IAC, IAT, MAF, MAP or TP DTCs are set.
No misfire DTCs are set.
No fuel trim DTCs are set.
Power enrichment not active.
Decel fuel cut-off not active.
Air/Fuel ratio at 14.7:1.
Engine speed is greater than or equal to 550 RPM.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and run engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. If bank 1 short term fuel trim indicates a change of greater than 6 percent, go to next step. If bank 1 short term fuel trim does not indicate a change of greater than 6 percent, go to step 4 .
DTC is intermittent. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If any additional DTCs are set, go to applicable DTC test.
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect bank 1 AIR crossover hose from AIR valve. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to next step. If air does not flow from valve, go to step 7 .
Check for restrictions or leaks in bank 1 AIR pipe, hoses and fittings. If a problem is found, go to step 8 . If no problem is found, go to step 9 .
Repair leaks or restrictions in bank 1 AIR hose between check valve and each bank. After repairs, go to step 10 .
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1415: AIR SYSTEM BANK 1 (5.7L "F" & "Y" BODIES)

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

AIR pump is used to lower tailpipe emissions on start-up. PCM supplies ground to AIR pump relay, energizing pump. PCM monitors the HO2S voltages to diagnose AIR system.

During the AIR test, the PCM activates the AIR pump during "closed-loop" operation. When AIR is activated, PCM monitors the HO2S voltages and short term fuel trim values for both banks of the engine. If AIR system is operating properly, the HO2S voltages should go low and short term fuel trim should go high.

DTC will set when PCM determines that the HO2S voltages for both banks did not respond as expected during the test. If only one sensor responded, PCM sets either DTC P1415 or P1416 to indicate which bank the AIR is inoperative.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine to "closed-loop" status. Turn off all accessories. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 1 HO2S 1 (left front) voltage display. If HO2S voltage drops to less than 222 mV, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If HO2S voltage does not drop to less than 222 mV, go to next step.
Ensure all hoses and pipes are connected and clamps secure. Check for heat damaged components. Repair as necessary. After repairs, go to step 6 . If components are okay, go to next step.
Disconnect hose from check valve at left exhaust manifold. Using scan tool, enable AIR pump. If air is present at hose outlet, go to step 7 . If air is not present, go to next step.
Repair restriction or blockage in AIR hoses/pipes between left exhaust manifold and where system branches to both sides of engine. After repairs, go to step 8 .
Repair as necessary. After repairs, go to step 8 .
Replace check valve. After replacing check valve, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Casting flash in exhaust manifold may restrict amount of airflow necessary to affect HO2S voltage. Remove air pipe from manifold and inspect passage.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

DTC P1416: AIR SYSTEM BANK 2 (4.3L "C" & "K" SERIES)

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

DTC will set when HO2S voltage does not go less than 222 mV within 1.3 seconds and short term fuel trim does not go greater than a predetermined amount.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and operate engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature and in "closed-loop". Using scan tool, command AIR pump on. Observe Short Term Fuel Trim Bank 2. If scan tool indicates a change of 16 percent within 30 seconds, go to next step. If scan tool does not indicate a change of 16 percent within 30 seconds, go to step 4 .
DTC P1416 is intermittent. If additional DTCs are set, diagnose affected DTCs. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect hose from check valve at left exhaust manifold. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to next step. If air does not flow from valve, go to step 7 .
Repair blockage or restrictions in AIR hose between check valve and each bank. If problem is found, go to step 8 . If no problems are found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536__dtc-p1416-air-system-bank-2) .
Check for restrictions or leaks in bank 2 AIR hose between check valve and other branches. If problem is found, go to next step. If no problems were found, diagnose air injection system.
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and run engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. If bank 1 short term fuel trim indicates a change of greater than 16 percent, go to next step. If bank 1 short term fuel trim does not indicate a change of greater than 16 percent, go to step 4 .
DTC is intermittent. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If any additional DTCs are set, go to applicable DTC test.
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect bank 2 AIR crossover hose from AIR valve. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to next step. If air does not flow from valve, go to step 7 .
Check for restrictions or leaks in bank 2 AIR pipe, hoses and fittings. If a problem is found, go to step 8 . If no problem is found, go to step 9 .
Repair leaks or restrictions in bank 2 AIR hose between check valve and each bank. After repairs, go to step 10 .
Repair as necessary. After repairs, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1416: AIR SYSTEM BANK 2 (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

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

DTC will set when HO2S voltage does not go less than 222 mV within 1.2 seconds and short term fuel trim does not go greater than a predetermined amount.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and operate engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. Observe Bank 1 Sensor 1 HO2S voltage as AIR pump is enabled. If HO2S voltage drops to less than 350 mV, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If HO2S voltage does not drop to less than 350 mV, go to next step.
Check AIR system hoses/pipes for proper connections or heat damage. Repair as necessary. After repairs, go to step 7 . If no problems were found, go to next step.
Disconnect hose from check valve at left exhaust manifold. Using scan tool, command AIR pump on. Observe if air flows from AIR valve. If air flows from valve, go to step 7 . If air does not flow from valve, go to next step.
Repair blockage or restrictions in AIR hose between check valve and each bank. After repairs, go to step 8 .
Repair as necessary. After repairs, go to step 8 .
Replace check valve. After replacing check valve, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1416: AIR SYSTEM BANK 2 (5.0L & 5.7L "C" & "K" SERIES)

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

No ECT, EVAP, HO2S, IAC, IAT, MAF, MAP or TP sensor DTCs are set.
No misfire DTCs are set.
No fuel trim DTCs are set.
System voltage greater than 10 volts for greater than 3 seconds.
IAT greater than 32°F (0°C).
Engine run time greater than 3 seconds.

AIR passive test failed.
No EVAP, HO2S, IAC, IAT, MAF, MAP or TP DTCs are set.
No misfire DTCs are set.
No fuel trim DTCs are set.
Power enrichment not active.
Decel fuel cut-off not active.
Air/Fuel ratio at 14.7:1.
Engine speed is greater than or equal to 550 RPM.
"Closed-loop" for a period of greater than 15 seconds.
Engine load less than 50 percent.
MAF less than or equal to 100 gm/s.
System voltage is greater than 10 volts.
ECT greater than or equal to 167°F (75°C) but less than 221°F (105°C).
IAT greater than 32°F (0°C).
Integrator greater than.95 but less than one for 3 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Install scan tool. Start and run engine for greater than 2 minutes. Ensure engine is operating at normal operating temperature. Using scan tool, command AIR pump on. If bank 2 short term fuel trim indicates a change of greater than 6 percent, go to next step. If bank 2 short term fuel trim does not indicate a change of greater than 6 percent, go to step 4 .
DTC is intermittent. If no additional DTCs are set, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If any additional DTCs are set, go to applicable DTC test.
Check AIR system hoses/pipes for proper connections or leaks. Repair as necessary. After repairs, go to step 8 . If no problems were found, go to next step.
Disconnect AIR hose at bank 2 check valve (AIR pump hose). Turn ignition on, engine off. Using scan tool, command AIR pump on. If air flows from hose, go to next step. If air does not flow from hose, go to step 7 .
Check for restrictions or leaks in bank 2 AIR pipe, hoses and fittings. If a problem is found, go to step 8 . If no problem is found, go to step 9 .
Repair restrictions or leaks in bank 1 AIR hose between check valve and each bank. After repairs, go to step 10 .
Repair as necessary. After repairs, go to step 10 .
Replace bank 2 check valve. After replacing check valve, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1416: AIR SYSTEM BANK 2 (5.7L "F" & "Y" BODIES)

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

AIR pump is used to lower tailpipe emissions on start-up. PCM supplies ground to AIR pump relay, energizing pump. PCM monitors the HO2S voltages to diagnose AIR system.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Start and operate engine to "closed-loop" status. Turn off all accessories. Using scan tool, select ENGINE 1 DATA LIST and monitor Bank 2 HO2S 1 (right front) voltage display. If HO2S voltage drops to less than 222 mV, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If HO2S voltage does not drop to less than 222 mV, go to next step.
Ensure all hoses and pipes are connected and clamps secure. Check for heat damaged components. Repair as necessary. After repairs, go to step 6 . If components are okay, go to next step.
Disconnect hose from check valve at right exhaust manifold. Using scan tool, enable AIR pump. If air is present at hose outlet, go to step 7 . If air is not present, go to next step.
Repair restriction or blockage in AIR hoses/pipes between left exhaust manifold and where system branches to both sides of engine. After repairs, go to step 8 .
Repair as necessary. After repairs, go to step 8 .
Replace check valve. After replacing check valve, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Casting flash in exhaust manifold may restrict amount of air flow necessary to affect HO2S voltage. Remove air pipe from manifold and inspect passage.

Use of FREEZE FRAME and/or FAILURE RECORDS mode will aid in locating intermittent condition. If DTC cannot be duplicated, information in data can be useful in determining how many miles since DTC set. This mode can also be used to determine how many ignition cycles diagnostic reported a pass and/or fail condition. Operating vehicle within FREEZE FRAME conditions (RPM, load, vehicle speed, temperature, etc.) will isolate when DTC failed.

DTC P1431: FUEL LEVEL SENSOR NO. 2 (RIGHT SIDE) CIRCUIT PERFORMANCE (5.7L "Y" BODY)

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

Fuel level sensor No. 2 measures fuel level changes within right fuel tank. When fuel level is low, sensor output voltage is high. When fuel level is high, sensor output voltage is low.

PCM uses inputs from fuel level sensor No. 1 (left side) and fuel level sensor No. 2 (right side) to calculate total fuel remaining in both tanks. This information is sent via serial data to BCM to be displayed on fuel gauge.

Diagnostic checks for stuck fuel level sensor No. 2 signal. If PCM determines fuel level signal appears to be stuck based on lack of signal variation, DTC will set.

DTC will set when following conditions are present

Secondary fuel tank is not empty.
More than 150 miles have been accumulated.
PCM does not detect that fuel level in right fuel tank moved by at least.80 gallon.

Secondary fuel tank is not empty.
Primary fuel tank is not full.
Engine operating greater than 60 minutes.
Primary tank does not achieve the top of its range.

Secondary fuel tank is not empty.
Primary fuel tank is not full.
Fuel level in both tanks does not change after travelling more than 200 miles.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC P0461 is also set. If DTC P0461 is set, diagnose DTC first. If DTC P0461 is not set, go to next step.
Disconnect fuel level sensor No. 2 connector at right fuel tank. Using scan tool, read fuel level sensor voltage. If voltage reading is zero volts, go to next step. If voltage reading is not as specified, go to step 9 .
Connect a fused jumper wire between fuel level sensor No. 2 connector signal and ground circuits. If voltage reading is zero volts, go to next step. If voltage reading is not zero volts, go to step 10 .
Using scan tool, monitor fuel level in left fuel tank. If left fuel tank is empty, add gasoline. Disconnect upper siphon jet pump feed pipe from right fuel tank. Insert siphon jet pump feed pipe into empty, approved gasoline container. Using scan tool, command fuel pump ON for 10 seconds. Measure volume of fuel in container. If volume is greater than.633 pint (.30L), go to next step. If volume is not as specified, go to step 11 .
Reconnect upper siphon jet pump feed pipe to right fuel tank. Disconnect upper siphon jet pump feed pipe from left fuel tank. Insert siphon jet pump feed pipe into empty, approved gasoline container. Using scan tool, command fuel pump ON for 8 seconds. Measure volume of fuel in container. If volume is greater than.703 pint (.33L), go to next step. If volume is not greater than.703 pint (.33L), go to step 12 .
Remove fuel level sensor No. 2 from right fuel tank. Check for foreign material (such as ice) in fuel tank. Repair fuel tank as necessary. After repairs, go to step 16 . If no foreign material is found in tank, go to next step.
Set DVOM to 400 ohm range. Connect DVOM between fuel level sensor No. 2 (sensor side) signal and ground circuits. Sweep sensor from stop to stop. If resistance varies smoothly from about 40-250 ohms, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If resistance does not vary smoothly from about 40-250 ohms, go to step 13 .
Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor No. 2 signal circuit for short to voltage. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor No. 2 signal circuit for open or short to ground. Repair as necessary. After repairs, go to step 16 . If circuit is okay, go to step 14 .
Inspect siphon jet pump feed pipe for restrictions. Repair as necessary. After repairs, go to step 16 .
Inspect siphon jet pump feed pipe for restrictions. Repair as necessary. After repairs, go to step 16 . If no restrictions are found, go to next step.
Replace fuel level sensor No. 2. After replacing fuel level sensor, go to step 16 .
Check terminal connections at PCM. Repair terminals as necessary. After repairs, go to step 16 . If terminals are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
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. If fuel level sensor is operating okay, check operation of jet pump. 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 P1432: FUEL LEVEL SENSOR NO. 2 (RIGHT SIDE) CIRCUIT LOW VOLTAGE (5.7L "Y" BODY)

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

Fuel level sensor No. 2 measures fuel level changes within right fuel tank. When fuel level is low, sensor output voltage is high. When fuel level is high, sensor output voltage is low.

Diagnostic checks for stuck fuel level sensor No. 2 signal. If PCM determines fuel level signal appears to be stuck based on lack of signal variation, DTC will set.

Conditions for setting DTC are: fuel level sensor No. 2 voltage is less than.39 volt and condition met for greater than 20 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor No. 2 voltage. If voltage reading is less than.39 volt, go to step 4 . If voltage reading is not less than.39 volt, go to next step.
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»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect fuel level sensor No. 2 connector at right fuel tank. Turn ignition on, with engine off. Observe fuel level sensor voltage on scan tool. If voltage reading is less than.39 volt, go to next step. If voltage reading is not less than.39 volt, go to step 7 .
Turn ignition off. Disconnect PCM harness connector. Check fuel level sensor No. 2 circuit for continuity to ground. If circuit is grounded, go to next step. If circuit is okay, go to step 8 .
Repair grounded fuel level sensor signal circuit PCM connector and sensor. After repairs, go to step 9 .
Replace fuel level sensor No. 2. After replacing fuel level sensor, go to step 9 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
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 P1433: FUEL LEVEL SENSOR NO. 2 (RIGHT SIDE) CIRCUIT HIGH VOLTAGE (5.7L "Y" BODY)

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

Fuel level sensor No. 2 measures fuel level changes within right fuel tank. When fuel level is low, sensor output voltage is high. When fuel level is high, sensor output voltage is low.

Diagnostic checks for stuck fuel level sensor No. 2 signal. If PCM determines fuel level signal appears to be stuck based on lack of signal variation, DTC will set.

Conditions for setting DTC are: fuel level sensor No. 2 voltage is greater than 2.9 volts and condition is present for greater than 2 minutes.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Warm engine to normal operating temperature. Using scan tool, monitor FAILED THIS IGNITION under DTC STATUS for DTC P1635 and P1639. If scan tool indicates that DTC P1635 and P1639 failed this ignition cycle, diagnose these DTCs first. If scan tool does not indicate that DTC P1635 and P1639 failed this ignition cycle, go to next step.
Turn ignition on, with engine off. Using scan tool, monitor fuel level sensor No. 2 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.
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»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect fuel level sensor No. 2 connector at right fuel tank. Check voltage of fuel level sensor signal circuit at sensor harness connector. If voltage reading is greater than 5 volts, go to step 15 . If voltage reading is not greater than 5 volts, go to next step.
Turn ignition off. Jumper fuel level sensor harness connector terminals together. Turn ignition on, with engine off. Observe fuel level sensor right tank display on scan tool. If voltage reading is 2.9 volts, go to step 9 . If voltage reading is not 2.9 volts, go to next step.
Jumper fuel level sensor signal circuit to a known-good ground. If voltage reading is less than 2.9 volts, go to step 10 . If voltage reading is not less than 2.9 volts, go to next step.
Turn ignition off. Disconnect PCM harness connector. Check for open in fuel level sensor signal circuit. If circuit is open, go to step 13 . If circuit is okay, go to step 16 .
Turn ignition off. Remove jumper from sensor harness connector. Disconnect both PCM harness connectors. Check resistance between fuel level sensor signal circuit at PCM harness connectors to all other circuit at PCM harness connectors. If resistance is 0-2 ohms, go to step 15 . If resistance is not 0-2 ohms, go to step 11 .
Turn ignition off. Disconnect PCM harness connectors. Check for open in fuel level sensor ground circuit. If circuit is open, go to step 14 . If circuit is okay, go to step 16 .
Check for poor connections at fuel level sensor harness connector. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to next step.
Replace fuel level sensor. After replacing sensor, go to step 18 .
Repair open in fuel level sensor signal circuit. After repairs, go to step 18 .
Repair open in fuel level sensor ground circuit. After repairs, go to step 18 .
Repair short to voltage in fuel level sensor ground circuit. After repairs, go to step 18 .
Check for poor connection at PCM harness connector. Repair as necessary. After repairs, go to step 18 . If connection is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 .
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 since 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 P1441: EVAP CANISTER PURGE SOLENOID FLOW DURING NON-PURGE (1.9L SATURN)

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

The EVAP control system checks for conditions that will cause EVAP system to purge continuously by commanding EVAP vent solenoid on and EVAP canister purge off (EVAP vent solenoid closed and purge valve to zero percent duty cycle). If fuel tank vacuum level increases during the SERVICE BAY TEST, a continuous purge flow condition is indicated. A "stuck open" or leaking purge valve will cause DTC P1441 to set. A continuous purge flow condition is detected when SERVICE BAY TEST is run using scan tool.

Connect scan tool. Turn ignition on, engine off. Using scan tool, view malfunction history DTCs. If DTC P0452 or P0453 is present, diagnose affected DTC first. If DTC P0452 or P0453 is not present, go to next step.
Using scan tool, command EVAP canister purge on and off. If solenoid clicks when commanded on and off, go to step 4 . If solenoid does not click when commanded on and off, go to next step.
Disconnect EVAP canister purge solenoid. Connect test light between solenoid harness connector terminals. Turn ignition on, engine off. If test light illuminates, replace solenoid. If test light does not illuminate, check for short in circuit between solenoid and PCM. Repair as necessary. If circuit is okay, replace PCM.
Remove fuel filler cap. Turn ignition on, engine off. Using scan tool, monitor fuel pressure parameter. If pressure is 1.3-1.7 volts, go to next step. If pressure is not 1.3-1.7 volts, refer to DTC P0452 or P0453 for diagnosis.
Install fuel filler cap. Start engine. Command vent solenoid on (closed) while commanding purge solenoid off (zero percent duty cycle). Monitor fuel tank pressure parameter. If fuel tank vacuum increases to greater than 2 volts, go to next step. If fuel tank vacuum does not increase to greater than 2 volts, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect EVAP purge solenoid harness connector. Start engine. Using scan tool, command vent solenoid on while commanding purge solenoid off. If fuel tank vacuum increases to greater than 2 volts, replace EVAP canister purge solenoid. If fuel tank vacuum pressure does not increase to greater than 2 volts, check circuit between canister purge solenoid and PCM for short to ground. Repair as necessary. If circuit is okay, replace PCM.

Check harness connectors for proper connection. Using scan tool, review malfunction history data and attempt to reproduce the conditions and fault. Check for foreign material or debris holding valve open.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (2.2L "J" BODY, 2.2L "S" SERIES & 2.4L "J" & "N" BODIES)

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

Evaporative Emission (EVAP) system is checked by applying vacuum to EVAP system and monitoring vacuum decay. Powertrain Control Module (PCM) monitors vacuum level by means of fuel tank vacuum sensor input. At a predetermined time, EVAP purge solenoid and EVAP vent solenoid are turned on. This allows engine vacuum to draw a small vacuum on entire EVAP system. DTC will set when EVAP is unable to detect vacuum during diagnostic test.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Using scan tool, check if DTC P0452, P0453 or P0460 is also set. If DTCs are set, diagnose affected DTC(s) first. If these DTCs are not set, go to next step.
Turn ignition on, engine off. Using scan tool, command EVAP canister purge valve and vent solenoid on and off. If purge valve and vent solenoid click, go to next step. If purge valve and vent solenoid do not click, perform PCM diagnosis. See appropriate SYSTEM & COMPONENT TESTING article.
Turn ignition off. Disconnect purge line from fuel tank at EVAP canister. Turn ignition on. Using scan tool, check fuel tank pressure sensor value. If fuel tank pressure sensor value is zero mm Hg, go to step 6 . If fuel tank pressure sensor value is not zero mm Hg, go to next step.
Check for pinched, kinked or plugged purge line from fuel tank to EVAP canister. Repair as necessary. After repairs, go to step 12 . If purge line is okay, go to DTC P0452 or P0453 diagnosis.
Zero pressure and vacuum gauges on EVAP Pressure/Purge Diagnostic Station (J-41413). Reconnect all EVAP hardware previously disconnected. Connect EVAP pressure/purge diagnostic station to EVAP service port. Using scan tool, command EVAP vent solenoid ON (closed). Using EVAP pressure/purge diagnostic station, attempt to pressurize EVAP system to 5 in. H2O. If specified pressure is achieved, go to next step. If specified pressure is not achieved, to step 8 .
Maintain EVAP system pressure at 5 in. H2O. Using scan tool, observe FUEL TANK PRESSURE. If scan tool displays 5 in. H2O, go to next step. If scan tool does not display 12 mm Hg, go to DTC P0452 or P0453 diagnosis.
Disconnect vacuum hose at EVAP canister purge valve (from throttle body). Connect a hand-held vacuum pump to EVAP canister purge valve vacuum source fitting. Apply 15 in. Hg vacuum. Using scan tool, command EVAP canister purge valve on. If vacuum is maintained, go to next step. If vacuum cannot be maintained, go to step 10 .
Check EVAP canister purge valve vacuum hoses for correct routing. If vacuum hoses are routed incorrectly, go to step 11 . If vacuum hoses are routed correctly, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace EVAP canister purge valve. After replacing canister valve, go to step 12 .
Correct EVAP vacuum hose routing. After repairs, go to next step.
Disconnect purge line from fuel tank at EVAP canister. Start engine. Using scan tool, activate EVAP SEAL SYSTEM function to seal EVAP system. Connect purge line from fuel tank to EVAP canister. Operate engine at 2500 RPM while monitoring fuel tank pressure value on scan tool. If fuel tank pressure value is zero in. H2O or greater, go to next step. If fuel tank pressure value is not zero in. H2O or greater, repeat step 2 .
Using scan tool, clear DTCs. Start and warm engine to normal operating temperature. Operate vehicle within the 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 .
Check if additional DTCs are set. Diagnose affected DTC(s). If no additional DTCs are set, system is okay.

Check for incorrect vacuum hose routing to EVAP canister purge valve. Check PCM connector for poor terminal connections. Check for damaged EVAP related wiring harness.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

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

Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized (purge on) by PCM. A vacuum switch in purge line is used to detect when system is being purged. PCM supplies and reads EVAP purge vacuum switch signal. If switch is open (purge detected) when not commanded by PCM, DTC P1441 will set.

Conditions required to set DTC are, no IAT, MAP, PCM or TP sensor DTCs set, DTC P0442 diagnostic test has passed and a continuous open purge flow condition is detected during diagnostic test (fuel tank pressure decreases to less than -11 in. H2O).

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P1655 is also set. If DTC P1655 is set, diagnose using P1655 tests. If DTC is not set, go to next step.
Turn ignition off. Remove fuel filler cap. Turn ignition on. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H2O, go to next step. If fuel tank pressure is not zero in. H2O, diagnose evaporative system.
Replace fuel filler cap. Using scan tool, capture FAIL RECORD data for DTC P1441 and clear DTCs. Install EVAP pressure/purge diagnostic station to EVAP service port. Using scan tool, command EVAP vent solenoid on (closed). Attempt to pressurize EVAP system using diagnostic station. If pressure reading of 5 in. H2O can be achieved, go to next step. If pressure reading of 5 in. H2O cannot be achieved, go to step 6 .
Maintain tank pressure at 5 in. H2O. Observe fuel tank pressure on scan tool. If fuel tank pressure is 5 in. H2O, go to next step. If fuel tank pressure is not 5 in. H2O, go to next step.
Check EVAP purge and source vacuum line routing and connections at EVAP purge solenoid. Repair as necessary. After repairs, go to step 9 . If routing and connections are okay, go to next step.
Remove engine vacuum source line from EVAP purge solenoid. Connect a hand-held vacuum pump to engine vacuum side of EVAP purge solenoid and apply 15 in. Hg vacuum. If solenoid holds vacuum, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If solenoid does not hold vacuum, go to next step.
Replace EVAP purge solenoid. After replacing solenoid, go to next step.
Correct EVAP purge and source vacuum line routing and connections. After repairs, go to next step.
Start engine. Remove fuel filler cap. Using scan tool's output tests function, select SEAL SYSTEM and activate. Replace fuel filler cap. Turn rotary switch on diagnostic station to PURGE position. Operate engine at idle while monitoring vacuum gauge on diagnostic station for a least 10 seconds. If vacuum holds at zero in. H2O while scan tool SEAL SYSTEM function is activated, system is okay. If vacuum does not hold at zero in. Hg, repeat step 3 .

Check for poor connection at PCM, damaged harness, incorrect vacuum line routing, or faulty or damaged evaporative canister.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (3.5L "W" BODY)

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

PCM will test the EVAP system for large and small leaks (P0440 and P0442), excess vacuum (P0446), purge during non-commanded operation (P1441), fuel tank pressure sensor and fuel level sensor faults (P0452, P0453, P0462 and P0463), and EVAP purge and vent faults (P0443 and P0449).

PCM monitors amount of vacuum in the EVAP system by monitoring the fuel tank pressure sensor. For the test, the PCM turns off the EVAP purge valve and turns on the EVAP vent valve when conditions for running the DTC have been met. This test indicates a leaking EVAP purge valve or flow during non-purge if fuel tank pressure sensor indicates increasing fuel tank vacuum. DTC will set after 2 consecutive failures of these tests and an increasing vacuum in the EVAP system is monitored.

Conditions for running this DTC are: no misfire, fuel trim, injector control circuit, AIR, ECT, EGR, HO2S, IAT, MAF, MAP, TP or VSS DTCs are set. Battery voltage 5-18 volts, BARO pressure greater than 75 kPa, fuel level 15-85 percent of full capacity for at least 10 seconds, ECT and IAT at start-up between 40-86°F (4-30°C), and ECT not greater than 46°F (8°C) or less than 36°F (2°C) of IAT at start-up.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if DTC P0453 is stored as history. If DTC P0453 is stored as history, diagnose using P0453 tests. If DTC P0453 is not set as history, go to next step.
Disconnect EVAP purge line from purge solenoid valve. Connect a vacuum gauge to solenoid purge port. Start and operate engine at idle. Within 30 seconds, command EVAP purge solenoid valve off using scan tool. If vacuum gauge indicates a vacuum reading, go to next step. If vacuum gauge does not indicate a vacuum reading, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace EVAP purge solenoid valve. After replacing solenoid valve, go to next step.
Using scan tool, clear DTCs. Turn ignition off. Wait 30 seconds, then 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 .
Using scan tool, select CAPTURED INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Check for poor connection at PCM, damaged harness, incorrect vacuum line routing, or faulty or damaged evaporative canister.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (3.8L "C", "G", "H" & "W" BODIES)

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

Evaporative (EVAP) emission system includes following components: fuel tank, EVAP vent solenoid, fuel tank pressure sensor, fuel pipes and hoses, vapor lines, fuel cap, EVAP emission canister, purge lines, and EVAP purge solenoid.

A leaking purge solenoid, EVAP purge and engine vacuum lines switched at EVAP purge solenoid, or EVAP purge solenoid driver circuit shorted to ground, will set DTC. Condition for setting DTC is when a continuous open purge flow condition is detected during the diagnostic test, fuel tank pressure decreases to less than -11 in. H2O.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If DTC P1676 is also set, diagnose DTC P1676 first. If DTC P1676 is not set, go to next step.
Turn ignition off. Remove fuel cap. Turn ignition on. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays zero in. H2O go to next step. If scan tool does not display zero in. H2O, repair faulty fuel tank pressure sensor circuit.
Zero pressure and vacuum gauges on EVAP Pressure/Purge Diagnostic Station (J-41413). Reinstall fuel cap. Read and record FAILURE RECORDS data for DTC P1441. Clear DTCs. Connect EVAP pressure/purge diagnostic station to EVAP service port. Using scan tool, command EVAP vent solenoid ON (closed). Using EVAP pressure/purge diagnostic station, attempt to pressurize EVAP system to 5 in. H2O. If specified pressure is achieved, go to next step. If specified pressure is not achieved, to step 6 .
Maintain EVAP system pressure at 5 in. H2O. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 5 in. H2O, go to next step. If scan tool does not display 5 in. H2O, repair faulty fuel tank pressure sensor circuit.
Check EVAP purge vacuum and source line routing and connections at EVAP purge solenoid. If no problem is found, go to next step. If a problem is found, go to step 9 .
Disconnect engine vacuum source line from EVAP purge solenoid. Connect a hand vacuum pump to engine vacuum side of EVAP purge solenoid. Attempt to apply 15 in. Hg vacuum to EVAP canister. If vacuum is maintained as specified, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If vacuum cannot be maintained as specified, go to next step.
Replace EVAP purge solenoid. After replacing EVAP purge solenoid, go to step 10 .
Correct line routing and connections as necessary. After repairs, go to next step.
Turn engine on. Remove fuel cap. Using scan tool OUTPUT TESTS function. Select and activate SEAL SYSTEM. Reinstall fuel cap. Run engine at 2500 RPM for 10 seconds while monitoring FUEL TANK PRESSURE on scan tool. If scan tool displays zero in. H2O, repair is complete. If scan tool does not display zero in. H2O, return to step 3 .

Check for incorrect vacuum hose routing or damage. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool FUEL TANK PRESSURE display while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (3.8L "F" BODY)

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

A leaking purge solenoid, EVAP purge and engine vacuum lines switched at EVAP purge solenoid, or EVAP purge solenoid driver circuit shorted to ground, will set DTC P1441. Condition for setting DTC is when a continuous open purge flow condition is detected during the diagnostic test, fuel tank pressure decreases to less than -11 in. H2O.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check for disconnected vacuum or purge lines. Check for missing or loose fuel filler cap. Repair as necessary. Check if DTC P0443 or P0449 is also set. If DTC(s) are set, diagnose affected DTCs first. If DTC(s) are not set and purge lines and fuel filler cap are okay, go to next step.
Turn ignition off. Remove EVAP canister line from EVAP canister purge valve to relieve fuel tank pressure. Turn ignition on, with engine off. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays zero in. H2O, go to next step. If scan tool does not display zero in. H2O, go to step 12 .
Zero pressure and vacuum gauges on EVAP Pressure/Purge Diagnostic Station (J-41413). Reconnect EVAP canister lines. Install Fuel Tank Cap Adapter (J-41415-0) between filler neck and fuel filler cap. Connect EVAP Station to fuel tank cap adaptor. Turn ignition on, with engine off. Using scan tool, read and record FAILURE RECORDS data for DTC P1441. Clear DTCs. Using scan tool, select EVAP PURGE/SEAL function and select seal option to seal EVAP system. Attempt to pressurize EVAP system to 5 in. H2O using diagnostic station. If specified pressure is achieved, go to next step. If specified pressure cannot be achieved, to step 6 .
Maintain EVAP system pressure at 5 in. H2O. Using scan tool, read FUEL TANK PRESSURE. If scan tool displays 5 in. H2O, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool does not display 5 in. H2O, go to step 10 .
Check EVAP purge vacuum and source line routing and connections at EVAP purge solenoid. If no problem is found, go to next step. If a problem is found, go to step 9 .
Connect vacuum gauge from EVAP Pressure/Purge Diagnostic Station to canister side of purge valve/solenoid. Turn ignition on, with engine off. Using scan tool, select EVAP PURGE/SEAL function and select seal option to seal EVAP system. Start and operate engine at idle. Increase engine speed from 1200-1500 RPM and observe vacuum level. If vacuum level is about zero in. H2O, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If vacuum level is not about zero in. H2O, go to next step.
Replace EVAP canister purge valve/solenoid. Check for carbon release into EVAP system. After repairs, go to step 13 .
Correct EVAP line routing and connections as necessary. After repairs, go to step 13 .
Check for restricted fuel tank vapor line or EVAP purge line. If a problem is found, go to step 13 . If no problems were found, go to DTC P0452 test.
Check for kinked or restricted canister purge line between EVAP canister purge valve and canister. Repair as necessary. After repairs, go to step 13 .
Turn ignition off. Remove EVAP canister line from fuel tank or EVAP canister to relieve fuel tank pressure. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure. If fuel tank pressure is about zero in. H2O, go to step 11 . If fuel tank pressure is not about zero in. H2O, go to DTC P0453 test.
Reconnect all EVAP hardware that were disconnected. Turn ignition on, with engine off. Using scan tool in PURGE/SEAL function, select seal option to seal EVAP system. Pressurize system to 15 in. H2O or higher by slowly turning EVAP Service Station rotary switch to PRESSURE position. Observe pressure on gauge with rotary switch in OFF/HOLD position. If EVAP pressure decreases to less than 10 in. H2O within 2 minutes, repeat step 3 . If EVAP pressure does not decrease to less than 10 in. H2O, system is okay.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

PCM will test EVAP system for the following conditions

Large and small leaks (P0440 and P0442).
Excess vacuum (P0446).
Purge flow during non-commanded condition (P1441).
Fuel pressure and level sensor faults (P0452, P0453, P0461, P0462 and P0463).
EVAP purge and vent valve faults (P1645 and P1646).

PCM monitors amount of vacuum in EVAP system by monitoring the fuel tank pressure sensor. PCM will turn off EVAP purge valve and will turn on EVAP vent valve when conditions for setting this DTC have been met. This test indicates a leaking EVAP purge valve or low during non-purge, if fuel tank pressure sensor indicates increasing fuel tank vacuum. DTC will set after 2 consecutive test failures or an increase in vacuum pressure in EVAP system is monitored.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC P1645 is stored as history DTC. If DTC P1645 is set, diagnose DTC P1645 first. If DTC P1645 is not set, go to next step.
Disconnect EVAP purge line from EVAP purge solenoid valve. Install a vacuum gauge to solenoid purge port. Start and operate engine at idle. After 30 seconds, command EVAP purge solenoid valve on and off using a scan tool. If vacuum gauge indicates a vacuum reading, go to next step. If vacuum gauge does not indicate a vacuum reading, fault is present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check EVAP purge solenoid valve for charcoal contamination. Replace as necessary.

Always diagnose fuel level sensor DTCs before performing this DTC test. Check history code for fuel level sensor related DTC.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (4.3L "C", "K" "L", "M", "S" & "T" SERIES)

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

Evaporative (EVAP) emissions canister purge is controlled by a solenoid valve which allows ported vacuum to purge canister when energized by VCM. A vacuum switch in purge line is used to detect when system is being purged. VCM supplies and reads a 12-volt reference to switch. DTC will set when EVAP system develops a vacuum greater than a calibrated value when purge is not commanded.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Disconnect EVAP purge line from EVAP purge solenoid. Connect vacuum gauge to solenoid purge port. Start and operate engine at idle. After 30 seconds, command EVAP purge solenoid off using scan tool. If vacuum gauge indicates any vacuum, go to next step. If vacuum gauge does not indicate any vacuum, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Disconnect purge solenoid harness connector. Check vacuum gauge. If vacuum is still indicated on gauge, go to next step. If vacuum is not indicated on gauge, go to step 5 .
Replace EVAP purge solenoid. After replacing solenoid, go to step 8 .
Turn ignition off. Disconnect VCM harness connector. Using a test light connected to battery voltage, probe EVAP purge solenoid driver circuit. Turn ignition on, with engine off. If test light illuminates, go to step 7 . If test light does not illuminate, go to next step.
Replace VCM. Program replacement PCM using required equipment. After replacing VCM, perform CKP System Variation Learning Procedure. See DTC P1336. After performing learn procedure, go to step 8 .
Repair short to ground in EVAP canister purge valve driver circuit. After repairs, go to next step.
Using scan tool, clear DTCs. Start engine. Select DTC and SPECIFIC DTC function, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this DTC test ran and passed, go to next step. If scan tool does not indicate that this DTC test ran and passed, repeat step 2 .
Using scan tool, select FREEZE FRAME and FAILURE RECORDS function. If any DTCs are present, diagnose affected DTCs. If no additional DTCs are present, system is okay.

Check vacuum hoses for damage. Check for faulty connections or damaged harness. If connections and harness appear okay, observe scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (4.3L, 5.0L & 5.7L "C", "G" & "K" SERIES)

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

Canister purge is controlled by a solenoid valve that allows ported vacuum to purge canister when energized. PCM supplies ground to energize solenoid valve which is pulse width modulated. Duty cycle is determined by closed loop feedback from HO2S. Duty cycle is calculated by VCM and output is commanded when certain conditions have been met.

A vacuum switch in purge line is used to detect when system is being purged. Normally closed switch will open when less than one in. Hg is present in purge line. VCM supplies a 12-volt reference to switch to monitor if evaporative emission control system is operating properly. DTC will set if switch is open when VCM is not commanding purge.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to EVAP service port. Ensure vacuum gauges on diagnostic station is zeroed. Turn rotary switch on diagnostic station to PURGE position. Start engine. Monitor vacuum gauge on diagnostic station. If vacuum reading is -15 in. H2O, go to next step. If vacuum reading is not -15 in. H2O, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect EVAP purge solenoid harness connector. Turn ignition on, engine off. Connect test light between battery voltage and EVAP purge solenoid connector terminal "B". If test light illuminates, go to next step. If test light does not illuminate, go to step 6 .
Turn ignition off. Disconnect VCM harness connector. Turn ignition on, engine off. Connect test light between battery voltage and EVAP purge solenoid connector terminal "B". If test light illuminates, go to next step. If test light does not illuminate, go to step 7 .
Repair short to ground in EVAP purge valve driver circuit. After repairs, go to step 8 .
Replace EVAP canister purge solenoid. After replacing solenoid, go to step 8 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
Using a scan tool, select DTC, CLEAR INFO. Perform SERVICE BAY TEST for EVAP system. After performing tests, go to next step.
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

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

PCM monitors amount of vacuum/pressure in EVAP system by monitoring fuel tank pressure sensor signal. PCM seals the EVAP system by commanding the EVAP purge solenoid off and EVAP vent valve on. PCM monitors fuel tank pressure sensor in order to determine if EVAP purge solenoid is leaking vacuum to EVAP system. DTC will set if EVAP system develops a vacuum greater than a predetermined value when purge is not commanded.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Disconnect EVAP purge line from EVAP purge solenoid valve. Connect vacuum gauge to solenoid purge port. Start and operate engine at idle. Using scan tool, command EVAP purge solenoid valve off. If vacuum gauge indicates a vacuum, go to next step. If vacuum gauge does not indicate vacuum, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Check EVAP canister purge solenoid for carbon contamination. Replace as necessary. After replacing canister purge solenoid, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Before replacing any components, check for misrouted harness, rubbed-through wire insulation, wire broken inside insulation, kinked or damaged vacuum hoses or for physical damage to system components.

DTC P1441: EVAP SYSTEM FLOW DURING NON-PURGE (5.7L "F" & "Y" BODIES)

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

PCM monitors amount of vacuum/pressure in EVAP system by monitoring fuel tank pressure sensor signal. PCM seals the EVAP system by commanding the EVAP purge solenoid off and EVAP vent valve on. PCM monitors fuel tank pressure sensor in order to determine if EVAP purge solenoid is leaking vacuum to EVAP system. This DTC sets if vacuum in EVAP system is greater than a predetermined value within a predetermined time. DTC will set when PCM detects a vacuum in the EVAP system when purge is not commanded.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Disconnect EVAP purge line from EVAP purge solenoid valve. Connect vacuum gauge to solenoid purge port. Start and idle engine. Using scan tool, command EVAP purge solenoid valve off. If vacuum gauge indicates a vacuum, go to step 4 . If vacuum gauge does not indicate vacuum, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check EVAP canister purge solenoid for carbon contamination. Replace as necessary. After replacing canister purge solenoid, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

If this DTC sets, and no misfire is currently present, vehicle may simply have been run low on fuel. This DTC being present with a properly functioning fuel sender circuit eliminates need for lengthy misfire diagnosis. Verify that there is an adequate fuel supply in tank. DTC will set when fuel level signal is greater than 6.82 volts.

Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. If OBD system check was performed previously, go to DTC P0300 test.

DTC P1483: ENGINE COOLING SYSTEM PERFORMANCE (3.1L "W" BODY & 3.4L "U" SERIES)

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

PCM monitors inputs from various sensors to adjust fuel delivery and spark timing. When a high coolant temperature is detected, the PCM may enter a Hot Fuel Enrichment (HFE) mode. During HFE mode, a richer air/fuel ratio is commanded which can cause exhaust emissions to exceed Federal standards.

PCM calculates engine coolant temperature value based on IAT, engine speed, vehicle speed and engine load. PCM compares the calculated value to the actual ECT sensor signal input. If ECT sensor signal input is higher than calculated coolant temperature value, due to a skewed ECT or IAT sensor signal or an actual hot engine condition, DTC will set and PCM will disable HFE.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if other DTCs are present. If other DTCs are present, diagnose affected DTCs first. If no other DTCs are present, go to next step.
Allow engine and vehicle temperature to stabilize to ambient temperature. Allowing vehicle to stabilize overnight will ensure most accurate results. Turn ignition on, engine off. Using scan tool, compare ECT and IAT sensor readings. If both sensors have the same reading, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If both sensors do not have the same reading, go to next step.
Place a thermometer near IAT sensor. Compare thermometer reading to IAT sensor reading on scan tool. If IAT sensor reading is close to actual ambient temperature, go to next step. If IAT sensor reading is not close to actual ambient temperature, go to step 6 .
Replace ECT sensor.
Replace IAT sensor.

A cooling system problem is the most likely cause for setting this DTC. Check cooling system.

PCM will richen air/fuel ratio when a high coolant temperature is monitored. The Hot Fuel Enrichment (HFE) condition can cause exhaust emissions to exceed Federal emissions standards. This DTC is required in order to prevent HFE from being active during a skewed ECT sensor condition or during an actual cooling system problem causing a hot engine coolant.

PCM will calculate ECT value based in IAT, engine speed, vehicle speed and engine load. If ECT value is higher than calculated coolant temperature, DTC P1483 will set and HFE is disabled.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if other DTCs are present. If other DTCs are present, diagnose affected DTCs first. If no other DTCs are present, go to next step.
Allow engine and vehicle temperature to stabilize to ambient temperature. Allowing vehicle to stabilize overnight will ensure most accurate results. Turn ignition on, engine off. Using scan tool, compare ECT and IAT sensor readings. If both sensors have the same reading, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If both sensors do not have the same reading, go to next step.
Place a thermometer near IAT sensor. Compare thermometer reading to IAT sensor reading on scan tool. If IAT sensor reading is close to actual ambient temperature, go to next step. If IAT sensor reading is not close to actual ambient temperature, go to step 6 .
Replace ECT sensor.
Replace IAT sensor.

A cooling system problem is the most likely cause for setting this DTC. Check cooling system.

When ignition switch is turned to ON position, and ECM lights MIL (bulb check), voltage change on MIL control circuit is used as a wake up signal to theft deterrent module. If a problem with this circuit prevents theft deterrent module from receiving wake up signal, this DTC will set.

Head of ignition key contains a transponder which is matched to a code in theft deterrent system. If a key is used that has the wrong or no code, vehicle will not start, and this DTC will set. DTC can also indicate theft deterrent module has detected a problem within theft deterrent system. Theft deterrent module sends a signal to ECM, causing this DTC to set.

DTC P1502: THEFT DETERRENT SYSTEM NO PASSWORD RECEIVED (3.0L "V" BODY)

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

This DTC will set if ECM has not been programmed with frequency code of theft deterrent module, or if there is a problem with circuit used for transmitting data (vehicle speed signal circuit). DTC will set when ECM has not received frequency code from theft deterrent module.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off. Raise and support drive axles. Start engine. Turn traction control system off, if equipped. With engine idling, place transmission in gear. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If displayed vehicle speed is zero MPH, go to next step.
Turn ignition off. Disconnect ECM connector located in engine compartment, in relay center. Connect test light between battery voltage and vehicle speed signal circuit at ECM harness connector. Turn ignition on, with engine off. Using DVOM set to AC, Hz, 4 volt scale, check voltage between ground and vehicle speed signal circuit at ECM harness connector. If DVOM indicates frequency 100-900 Hz, go to step 5 . If DVOM does not indicate frequency 100-900 Hz, go to next step.
Turn ignition off. Disconnect theft deterrent module harness connector. Check vehicle speed signal circuit for open, short to ground or short to voltage. Repair as necessary, then go to step 6 . If circuit is okay, go to step 7 .
Turn ignition off. Reconnect ECM connector. Disconnect theft deterrent module connector. Connect Signal Generator Tester (J-33431-B) between ground and vehicle speed signal circuit at theft deterrent module harness connector. Turn ignition on. Turn tester on. Set tester to generate a VSS signal. Using scan tool, monitor vehicle speed. If displayed vehicle speed is greater than zero MPH, diagnose anti-lock brake system. If displayed vehicle speed is zero MPH, go to step 8 .
Repair vehicle speed signal circuit between theft deterrent module harness connector and ECM. After repairs, go to step 10 .
Check for poor connections and terminal tension at theft deterrent module harness connector. Repair as necessary. After repairs, go to step 10 . If connections and terminals are okay, diagnose theft deterrent system.
Check for poor connections and terminal tension at ECM harness connector. Repair as necessary. After repairs, go to step 10 . If connections and terminals are okay, go to next step.
Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P1502 is set, go to step 2 . If DTC P1502 is not set, go to next step.
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.

If ECM and theft deterrent module have not been properly programmed, this DTC may set and vehicle will not start.

This DTC indicates that ECM has been programmed with a frequency code that does not match code in theft deterrent module.

Wrong ignition key, or use of a key without transponder will cause this DTC to set as well as no-start condition. If ECM and theft deterrent module have not been properly programmed, this DTC may set and vehicle will not start.

DTC P1508: IDLE SPEED LOW-IAC SYSTEM RESPONDING (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.

If engine idle speed is less than the desired idle speed and all test conditions are met, the PCM will cycle the IAC valve and expect to see a change in the MAF sensor reading. If no change occurs, DTC P1508 will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
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.
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 5 . If noid light does not cycle, go to next step.
Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 8 .
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.
Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
Replace IAC valve.
Check IAC terminal contacts at PCM harness connector C1. Repair as necessary. If terminal contacts are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

DTC P1508: IAC SYSTEM LOW RPM (4.3L "C", "K", "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 means more air is allowed to bypass the throttle plate (higher idle). DTC will set when change in MAF is greater than 3 gm/sec.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Set parking brake and block drive wheels. Start and operate engine at idle. Turn off all accessories. Using scan tool, command engine speed to 1200 RPM, then to 500 RPM. If engine RPM corresponds within 100 RPM of commanded speed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine RPM does not correspond within 100 RPM of commanded speed, go to next step.
Turn ignition off. Disconnect IAC valve harness connector. Using DVOM, check resistance between IAC valve harness connector terminals "A" and "B", and between terminals "C" and "D". If resistance between these terminals is 40-80 ohms, go to next step. If resistance between these terminals is not 40-80 ohms, go to step 13 .
Check resistance between IAC valve terminals "B" and "C", and between terminals "A" and "D". If resistance between these terminals is infinite, go to next step. If resistance between these terminals is not infinite, go to step 13 .
Leave IAC valve harness connector disconnected. Start engine. Using test light connected to ground, probe each of the IAC valve harness connector terminals while commanding ON using the IAC RESET function of scan tool. If test light flashes on and off at all terminals, go to step 9 . If test light does not flash on and off at all terminals, go to next step.
If test light stayed on at any of the terminals during IAC reset function, go to step 8 . If test light did not stay on at any of the terminals during IAC reset function, go to next step.
Check for open or short to ground in IAC valve circuit where test light did not turn on or flash. If circuit is faulty, go to step 11 . If circuit is okay, go to step 10 .
Check for short to voltage in IAC valve circuit where test light remained on. If circuit is faulty, go to step 11 . If circuit is okay, go to step 10 .
Turn ignition off. Remove IAC valve. Check IAC valve and throttle body passages for carbon deposits. If carbon deposits are present, go to step 12 . If no carbon deposits are present, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for poor connections at VCM. If connections are faulty, go to next step. If connections are okay, go to step 14 .
Repair as necessary. After repairs, go to step 15 .
Clean IAC valve and passages. After cleaning, go to step 15 .
Replace IAC valve. After replacing valve, go to step 15 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 that this DTC ran and passed, go to next step. If scan tool does not display that this DTC ran and passed, return to step 2 .
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 stopped IAC valve, tampered throttle stop screw, and damaged throttle or linkage. Check for fuel system running too rich or too lean. Check throttle body bore for foreign material. Reset IAC using scan tool.

DTC P1508: IDLE AIR 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). DTC will set when change is MAF is greater than 3 gm/sec.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Set parking brakes and block drive wheels. Start engine. Ensure all accessories are off. Using scan tool, command engine speed to 1200 RPM then to 500 RPM. If engine speed corresponds within 100 RPM of commanded speed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine speed does not correspond within 100 RPM of commanded speed, go to next step.
Turn ignition off. Disconnect IAC valve harness connector. Check resistance between IAC valve terminals "A" and "B", and terminals "C" and "D". If resistance is 40-80 ohms, go to next step. If resistance is not 40-80 ohms, go to step 13 .
Check resistance between IAC valve terminals "B" and "C", and terminals "A" and "D". If resistance is infinite, go to next step. If resistance is not infinite, go to step 13 .
Install Connector Test Adapter (J-35616-A) to IAC valve harness connector. Start engine. Connect test light between ground and connector test adapter terminals. Using scan tool, command RESET IAC on for each circuit tested. If test light flashes on and off at all terminals, go to step 9 . If test light does not flash on and off at all terminals, go to next step.
If test light stayed on at any of the terminals during IAC valve reset function, go to step 8 . If test light did not stay on during the IAC valve reset function, go to next step.
Check for open or short to ground in IAC valve circuit that did not flash test light. If problem is found, go to step 11 . If no problems were found, go to step 10 .
Check for short to voltage in IAC valve circuit where test light stayed on. If problem is found, go to step 11 . If no problems were found, go to step 10 .
Turn ignition off. Remove IAC valve. Check for carbon deposits on valve and throttle body passages. If problem is found, go to step 12 . If no problems were found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for poor connection at VCM. If problem is found, go to next step. If no problems were found, go to step 14 .
Repair as necessary. After repairs, go to step 15 .
Clean IAC valve and passages. After repairs, go to step 15 .
Replace IAC valve. Perform IAC reset procedure if IAC valve is replaced. See appropriate ON-VEHICLE ADJUSTMENTS article. After replacing IAC valve, go to step 15 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

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 too lean or too rich fuel system. Check throttle body bore for foreign material. IAC reset is done with scan tool in miscellaneous function mode.

DTC P1509: IDLE SPEED HIGH-IAC SYSTEM RESPONDING (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

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

If engine idle speed is greater than the desired idle speed and all test conditions are met, the PCM will cycle the IAC valve and expect to see a change in the MAF sensor reading. If no change occurs DTC P1509 will set. If a change occurs indicating the IAC is responding, then DTC P0507 will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
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. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine speed is not within 50 RPM of desired value, go to next step.
Disconnect IAC valve. Install IAC Noid Light (J-37027). Start engine. Command engine speed up to 1500 RPM, down to 700 RPM, then back to 1500 RPM while monitoring noid light. If noid light cycles Red and Green (never off), go to step 5 . If noid light does not cycle, go to next step.
Check all IAC circuits for open, short to ground or short to voltage. Repair as necessary. If circuits are okay, go to step 8 .
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.
Check for poor terminal contact at IAC harness connector. Repair as necessary. If terminal contacts are okay, go to next step.
Replace IAC valve.
Check IAC terminal contacts at PCM harness connector C1. Repair as necessary. If terminal contacts are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

Reviewing the FAILURE REC may help diagnose an intermittent failure by showing how long ago and under what conditions the DTC set.

DTC P1509: IAC SYSTEM HIGH RPM (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

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

VCM commands IAC in counts. A higher count, allows more air to bypass throttle plate (higher idle). DTC will set when change in MAF is greater than 3 gm/sec.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Set parking brake and block drive wheels. Start and operate engine at idle. Turn off all accessories. Using scan tool, command engine speed to 1200 RPM, then to 500 RPM. If engine RPM corresponds within 100 RPM of commanded speed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine RPM does not correspond within 100 RPM of commanded speed, go to next step.
Turn ignition off. Disconnect IAC valve harness connector. Using DVOM, check resistance between IAC valve harness connector terminals "A" and "B", and between terminals "C" and "D". If resistance between these terminals is 40-80 ohms, go to next step. If resistance between these terminals is not 40-80 ohms, go to step 13 .
Check resistance between IAC valve terminals "B" and "C", and between terminals "A" and "D". If resistance between these terminals is infinite, go to next step. If resistance between these terminals is not infinite, go to step 13 .
Leave IAC valve harness connector disconnected. Start engine. Using test light connected to ground, probe each of the IAC valve harness connector terminals while commanding ON using the IAC RESET function of scan tool. If test light flashes on and off at all terminals, go to step 9 . If test light does not flash on and off at all terminals, go to next step.
If test light stayed on at any of the terminals during IAC reset function, go to step 8 . If test light did not stay on at any of the terminals during IAC reset function, go to next step.
Check for open or short to ground in IAC valve circuit where test light did not turn on or flash. If circuit is faulty, go to step 11 . If circuit is okay, go to step 10 .
Check for short to voltage in IAC valve circuit where test light remained on. If circuit is faulty, go to step 11 . If circuit is okay, go to step 10 .
Turn ignition off. Remove IAC valve. Check IAC valve and throttle body passages for carbon deposits. If carbon deposits are present, go to step 12 . If no carbon deposits are present, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for poor connections at VCM. If connections are faulty, go to next step. If connections are okay, go to step 14 .
Repair as necessary. After repairs, go to step 15 .
Clean IAC valve and passages. After cleaning, go to step 15 .
Replace IAC valve. After replacing valve, go to step 15 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 that this DTC ran and passed, go to next step. If scan tool does not display that this DTC ran and passed, return to step 2 .
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.

DTC P1509: IAC 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.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Set parking brakes and block drive wheels. Start engine. Ensure all accessories are off. Using scan tool, command engine speed to 1200 RPM then to 500 RPM. If engine speed corresponds within 100 RPM of commanded speed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If engine speed does not correspond within 100 RPM of commanded speed, go to next step.
Turn ignition off. Disconnect IAC valve harness connector. Check resistance between IAC valve terminals "A" and "B", and terminals "C" and "D". If resistance is 40-80 ohms, go to next step. If resistance is not 40-80 ohms, go to step 13 .
Check resistance between IAC valve terminals "B" and "C", and terminals "A" and "D". If resistance is infinite, go to next step. If resistance is not infinite, go to step 13 .
Install Connector Test Adapter (J-35616-A) to IAC valve harness connector. Start engine. Connect test light between ground and connector test adapter terminals. Using scan tool, command RESET IAC on for each circuit tested. If test light flashes on and off at all terminals, go to step 9 . If test light does not flash on and off at all terminals, go to next step.
If test light stayed on at any of the terminals during IAC valve reset function, go to step 8 . If test light did not stay on during the IAC valve reset function, go to next step.
Check for open or short to ground in IAC valve circuit that did not flash test light. If problem is found, go to step 11 . If no problems were found, go to step 10 .
Check for short to voltage in IAC valve circuit where test light stayed on. If problem is found, go to step 11 . If no problems were found, go to step 10 .
Turn ignition off. Remove IAC valve. Check for carbon deposits on valve and throttle body passages. If problem is found, go to step 12 . If no problems were found, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Check for poor connection at VCM. If problem is found, go to next step. If no problems were found, go to step 14 .
Repair as necessary. After repairs, go to step 15 .
Clean IAC valve and passages. After repairs, go to step 15 .
Replace IAC valve. Perform IAC reset procedure if IAC valve is replaced. See appropriate ON-VEHICLE ADJUSTMENTS article. After replacing IAC valve, go to step 15 .
Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTCs are displayed, go to applicable DTC test.

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 P1510: THROTTLE CONTROL SYSTEM-IN LIMITATION (3.0L "V" BODY)

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

This DTC will run when battery voltage is greater than 7 volts and DTC learn procedure is not active. DTC will set when Pulse Width Modulation (PWM) is greater than 80 percent for greater than 6 seconds.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check electronic throttle control system of any electromagnetic interference or nearby high voltage source. If a problem is found, go to step 4 If no problems were found, go to next step.
Replace ECM. Program replacement ECM using required equipment. Ensure theft deterrent system interfaces with replacement ECM. Program new ECM with frequency code of theft deterrent module. After replacing ECM, go to step 5 .
Reroute wires or harnesses as necessary. After rerouting wires or harnesses, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

DTC P1511: THROTTLE CONTROL SYSTEM - BACK-UP SYSTEM PERFORMANCE (3.0L "V" BODY)

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

This DTC will run when vehicle is not moving, engine speed is less than 250 RPM, ECT is less than 5°C, battery voltage greater than 10 volts and accelerator pedal position is less than 15 percent. DTC will set when TP sensor is less than 3.7 percent or greater than 9.8 percent.

This DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles if no failures is reported by this diagnostic or any other emission related diagnostics. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Diagnose and repair any electronic throttle control related DTCs first. If no other DTCs are set, go to next step.
Inspect throttle body and ensure throttle valve is in closed position. If throttle valve is closed, go to next step. If throttle valve is not closed, go to step 7 .
Using scan tool, monitor TP sensors No. 1 and 2. If voltage reading is.16-.80 volt, go to step 8 . If voltage reading is not.16-.80 volt, go to next step.
Check TP sensors No. 1 and 2 circuit for open or short to ground. If circuit is faulty, go to next step. If circuit is okay, go to step 8 .
Repair as necessary. After repairs, go to step 9 .
Repair sticking or binding throttle valve. After repairs, go to step 9 .
Replace ECM. Program replacement ECM using required equipment and program new ECM with frequency code of the theft deterrent module that is currently on vehicle. After replacing ECM, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

DTC P1514: TAC SYSTEM MAF PERFORMANCE (3.8L "F" BODY & 5.7L "Y" BODY)

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

PCM uses Throttle Position (TP) sensor, Barometric Pressure (BARO) sensor, Intake Air Temperature (IAT) sensor and engine RPM inputs to calculate and expected Mass Airflow (MAF) value. PCM compares this value to MAF value and a speed density calculation to verify proper throttle operation.

Conditions for setting DTC are: PCM detects that the difference between actual airflow (MAF) and speed density calculated airflow is greater than expected and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If DTC P0101, P0102, P0103, P0107, P0108, P0112, P0113, P1111 or P1112 is also set, diagnose affected DTC(s) first. If DTC(s) is not set, go to next step.
Inspect throttle for loose or damaged TP sensor, loose or damage throttle blade, broken throttle shaft or drive mechanism damage. If any of these conditions exist, replace throttle body and go to next step. If none of these conditions exist, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.

Inspect throttle blade for being broken, bent or missing. Inspect TP sensor for proper installation (a misaligned sensor will set this DTC)

DTC P1515: PREDICTED VS ACTUAL TP PERFORMANCE (3.8L "F" BODY)

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

Commanded throttle position (based on accelerator pedal position and possibly other limiting factors) is compared to actual throttle position. Both values should be within calibrated range. Commanded and actual throttle position are monitored redundantly by both PCM and TAC modules.

Conditions for setting DTC are: PCM detects that commanded and actual throttle positions are not within a calibrated range of each other and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If DTC P1120, P1220 or P1221 is also set, diagnose these affected DTCs first. If these DTCs are not set, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool, monitor TP sensors No. 1 and 2 angles in TAC data list. Slowly depress accelerator pedal to wide open throttle. Slowly return to closed throttle. If TP angles increase as throttle blade is opened and decrease as throttle is closed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If TP angles does not increase, go to next step.
Turn ignition off. Disconnect Throttle Actuator (TAC) module harness connector. Turn ignition on. Check voltage across TAC motor HI and LO circuits at TAC harness connector. If voltage reading is 7.5-8.5 volts, go to step 15 . If voltage reading is not 7.5-8.5 volts, go to next step.
Turn ignition on. Check voltage between ground and on each TAC circuit (motor HI and LO circuits) at TAC harness connector. If any voltage is present, go to step 9 . If no voltage is present, go to next step.
Check continuity on each TAC circuit (motor HI and LO circuits) between TAC harness connector and TAC module harness connector. If continuity exists on both circuits, go to next step. If continuity does not exist on both circuits, go to step 10 .
Check for short to ground on each TAC circuit (motor HI and LO circuits). If circuit is faulty, go to step 11 . If circuit is not faulty, go to next step.
Check continuity between each TAC circuit (motor HI and LO circuits) and all other circuits in the TAC module connector. If continuity exists, go to step 12 . If continuity does not exist, go to step 13 .
Repair short to voltage on affected TAC circuit. After repairs, go to step 17 .
Repair open or high resistance on affected TAC circuit. After repairs, go to step 17 .
Repair short to ground on affected TAC circuit. After repairs, go to step 17 .
Repair circuits that are shorted together. After repairs, go to step 17 .
Check for poor connections at TAC module connectors. If a problem is found, go to step 17 . If no problems were found, go to next step.
Replace TAC module. After replacing module, go to step 17 .
Check for poor connections at TAC harness connector. If problem is found, go to step 17 . If no problems were found, go to next step.
Replace throttle body/TAC assembly. After replacing throttle body assembly, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

If no problem is found, check for temperature related mechanical problems or binding. Components may not move freely in extreme heat or cold (ice) conditions.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1515: COMMANDED VS ACTUAL TP PERFORMANCE-PCM (5.7L "Y" BODY)

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

Conditions for setting DTC are: PCM detects that commanded and actual throttle positions are not within a calibrated range of each other and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If DTC P1120, P1220 and P1221 are also set, diagnose these affected DTCs first. If these DTCs are not set, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool in TAC DATA LIST option, monitor TP sensors No. 1 and No. 2 angles. Slowly depress accelerator pedal to wide open throttle. Slowly return to closed throttle. If TP angles increase (about 100 percent) as throttle blade is opened and decrease as throttle is closed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If TP angles does not increase, go to next step.
Turn ignition off. Disconnect Throttle Actuator Control (TAC) harness connector. Turn ignition on, with engine off. Check voltage between TAC motor high and low circuits at TAC harness connector terminals. If voltage reading is 7.5-8.5 volts, go to step 15 . If voltage reading is not 7.5-8.5 volts, go to next step.
Check voltage between ground and TAC motor high and low circuits at TAC harness connector. If any voltage is present, go to step 9 . If no voltage is present, go to next step.
Check continuity on each TAC motor high and low circuits between TAC harness connector and TAC module harness connector. If continuity exists, go to next step. If continuity does not exist, go to step 10 .
Check for short to ground on each TAC motor high and low circuits. If circuit is shorted, go to step 11 . If circuit is okay, go to next step.
Check for continuity between each TAC motor high and low circuits and all other circuits in the TAC module connector. If continuity exists, go to step 12 . If continuity does not exist, go to step 13 .
Repair short to voltage on affected circuit. After repairs, go to step 17 .
Repair open or high resistance on affected circuit. After repairs, go to step 17 .
Repair short to ground on affected circuit. After repairs, go to step 17 .
Repair circuits that are shorted together. After repairs, go to step 17 .
Check for poor connections at TAC module connectors. Repair as necessary. After repairs, go to step 17 . If connections are okay, go to next step.
Replace TAC module. After replacing module, go to step 17 .
Check for poor connections at TAC connectors. Repair as necessary. After repairs, go to step 17 . If connections are okay, go to next step.
Replace throttle body assembly. After replacing throttle body, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

If no problem is found, check for temperature related mechanical problems or binding. Components may not move freely in extreme heat or cold (ice) conditions.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1516: COMMANDED VS ACTUAL TP PERFORMANCE (3.0L "V" BODY)

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

This DTC will run when the Electronic Throttle Control (ETC) learn procedure is not active. DTC will set when difference between the calculated and actual throttle position is greater than what is known. ECM will illuminate MIL and records the operating conditions in the Freeze Frame data on the second consecutive drive trip that the diagnostic runs and fails. DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles in which no failures are reported of this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose affected DTCs. If not other DTCs are set, go to next step.
Visually inspect throttle body. Ensure throttle valve is closed. If throttle valve is closed, go to next step. If throttle valve is not closed, go to step 7 .
Using scan tool, monitor TP sensors No. 1 and 2 voltages. If voltage reading is.16-.80 volt, go to step 8 . If voltage reading is not.16-.80 volt, go to next step.
Check for open or short to ground in TP sensors No. 1 and 2 circuit. If circuit is faulty, go to next step. If circuit is okay, go to step 8 .
Repair as necessary. After repairs, go to step 9 .
Repair sicking or binding throttle valve. After repairs, go to step 9 .
Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1516: COMMANDED VS ACTUAL TP PERFORMANCE (3.8L "F" BODY)

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

Conditions for setting DTC are: TAC module detects that commanded and actual throttle positions are not within a calibrated range of each other or PCM and TAC cannot determine throttle position or both sensors are invalid and these conditions are present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If DTC P1120, P1220 or P1221 is set, diagnose affected DTC(s) first. If DTC P1120, P1220 or P1221 is not set, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool on TAC DATA LIST option, monitor TP sensors No. 1 and No. 2 angles. Slowly depress accelerator pedal to wide open throttle. Slowly return pedal to closed throttle. If TP angles (about 100 percent) increase as throttle blade is open and decrease as throttle is closed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If angles does not increase, go to next step.
Turn ignition off. Disconnect TAC motor harness connector. Turn ignition on. Check voltage across TAC motor high and low circuit at harness connector. If voltage reading is 7.5-8.5 volts, go to step 15 . If voltage reading is not 7.5-8.5 volts, go to next step.
Check voltage between ground and each TAC motor high and low circuits at harness connector. If any voltage is present, go to step 9 . If no voltage is present, go to next step.
Check continuity of each TAC motor high and low circuits between TAC connector and TAC module connector. If continuity exists, go to next step. If continuity does not exist, go to step 10 .
Check for short to ground on each TAC motor high and low circuits. If circuit is shorted, go to step 11 . If circuit is okay, go to next step.
Check for continuity between each TAC motor high and low circuits and all other circuits at TAC module connector. If continuity exists, go to step 12 . If continuity does not exist, go to step 13 .
Repair short to voltage on affected throttle actuator circuit(s). After repairs, go to step 17 .
Repair open or high resistance on affected throttle actuator circuit(s). After repairs, go to step 17 .
Repair short to ground on affected throttle actuator circuit(s). After repairs, go to step 17 .
Repair circuits that are shorted together. After repairs, go to step 17 .
Check for poor connections at TAC module connector. Repair as necessary. After repairs, go to step 17 . If connections are okay, go to next step.
Replace TAC module. After replacing module, go to step 17 .
Check for poor connections at TAC connector. Repair as necessary. After repairs, go to step 17 . If connections are okay, go to next step.
Replace throttle body/TAC assembly. After replacing throttle body, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1516: COMMANDED VS ACTUAL TP PERFORMANCE-TAC (5.7L "Y" BODY)

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

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Using scan tool, monitor TP sensors No. 1 and No. 2 angles. Slowly depress accelerator pedal to wide open throttle. Slowly return pedal to closed throttle. If TP angles increase as throttle blade is open and decrease as throttle is closed, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If angles does not increase, go to next step.
Remove duct from throttle body assembly. Disconnect throttle actuator motor connector. Manually rotate throttle blade to wide open throttle and then close throttle blade while monitoring scan tool. If TP angles increase as throttle blade is open and decrease as throttle is closed, go to next step. If TP angles does not increase, go to step 10 .
Turn ignition off. Connect a test light across throttle actuator motor connector. Turn ignition on briefly. If test light illuminates, go to step 9 . If test light does not illuminate, go to next step.
Turn ignition off. Leave throttle actuator motor disconnected. Disconnect Throttle Actuator Control (TAC) module connector containing throttle actuator circuits. Turn ignition on, with engine off. Using DVOM, check voltage between battery ground and both throttle actuator circuits. If any voltage is present, go to step 11 . If no voltage is present, go to next step.
Using DVOM, check continuity of both throttle actuator circuits between throttle actuator and TAC module. If continuity exists on both circuits, go to next step. If continuity is not as specified, go to step 12 .
Check continuity between battery ground and both throttle actuator circuits. If continuity exists on both circuits, go to step 14 . If continuity is not as specified, go to next step.
Check continuity between both throttle actuator circuits and all other circuits in both TAC module connector. If continuity exists between any circuit(s), go to step 14 . If continuity does not exist between any circuit, go to step 16 .
Check for poor terminal connections at throttle actuator harness connector. Repair or replace terminals. After repairs, go to step 18 . If terminals are okay, go to next step.
Replace throttle body assembly. After replacing throttle body, go to step 18 .
Repair short to voltage in affected throttle actuator circuit(s). After repairs, go to step 18 .
Repair open in affected throttle actuator circuit(s). After repairs, go to step 18 .
Repair short to ground in affected throttle actuator circuit(s). After repairs, go to step 18 .
Repair circuits shorted together. After repairs, go to step 18 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 18 .
Check for poor terminal connections at TAC module harness connector. Repair or replace terminals. After repairs, go to step 18 . If terminals are okay, go to next step.
Replace TAC module. After replacing module, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1517: TAC MODULE PROCESSOR (3.8L "F" BODY & 5.7L "Y" BODY)

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

Throttle Actuator Control (TAC) module contains data which is essential for proper TAC system operation. TAC module continuously check integrity of this data.

When TAC module is unable to write or read data to and from RAM or TAC module is unable to correctly read data from flash memory or an internal TAC module processor fault is detected, DTC will set.

DTC will set when TAC module determines that an internal data test did not pass and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Replace TAC module. After replacing module, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1518: PCM TO TAC MODULE SERIAL DATA CIRCUIT (3.8L "F" BODY)

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

PCM and Throttle Actuator Control (TAC) module communicate through a dedicated serial data circuit. This diagnostic monitors accuracy of serial data transmission between PCM and TAC module. If a loss of data or invalid data is detected, this DTC will set.

Conditions for setting this DTC are, invalid or missing serial data messages are detected for a predetermined amount of time and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, review and record FAILURE RECORDS data and note parameters. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC until this DTC runs. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicates that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect Throttle Actuator Control (TAC) module harness connector. Check voltage between ground and TAC module ignition feed circuit. If voltage reading is zero volts, go to next step If voltage reading is not zero volts, go to step 10 .
Turn ignition on. Check voltage between ground and TAC module ignition feed circuit. If battery voltage is present, go to next step. If battery voltage is not present, go to step 12 .
Using a test light connected to battery voltage, probe TAC module ground circuit. If test light illuminates, go to next step. If test light does not illuminate, go to step 13 .
Check voltage between ground and both TAC module serial data circuits. If voltage reading is 2-5 volts, go to step 14 . If voltage reading is not 2-5 volts, go to next step.
If voltage is greater than 2-5 volts, go to step 11 . If voltage is not greater than 2-5 volts, go to next step.
If voltage is less than 2-5 volts, go to next step.
Check for open/short to ground in serial data circuit. Repair as necessary. After repairs, go to step 18 . If circuit is okay, go to step 16 .
Repair short to voltage in ignition feed circuit. After repairs, go to step 18 .
Repair short to voltage on TAC module serial data circuit. After repairs, go to step 18 .
Repair open/short to ground in ignition feed circuit. After repairs, go to step 18 .
Repair open in TAC module ground circuit. After repairs, go to step 18 .
Check for poor serial data connections at TAC module. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to next step.
Replace TAC module. After replacing module, go to step 18 .
Check for poor connections at PCM. Repair as necessary. After repairs, go to step 18 . If connections are okay, go to next step.
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

Check TAC module power and ground circuits and PCM/TAC module serial data circuits for intermittent connections. An intermittent problem can be caused by misrouted harness, rubbed-through wire insulation or broken wire inside insulation.

DTC P1518: PCM TO TAC MODULE SERIAL DATA CIRCUIT (5.7L "Y" BODY)

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

Conditions for setting this DTC are, invalid or missing serial data messages are detected for a predetermined amount of time and condition is present for less than one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, engine off. Using test light connected to ground, probe both ends of THROT CONT fuse (located in underhood fuse block). If test light illuminates on at least one side of fuse, go to next step. If test light does not illuminate on either end of fuse, check ignition relay.
Turn ignition off. Using test light probe both ends of THROT CONT fuse. If test light illuminates, go to step 31 . If test light does not illuminate, go to next step.
Using scan tool, verify if DTC P0606 is also set. If DTC P0606 is set, diagnose DTC P0606 first. If DTC P0606 is not set, go to next step.
Operate engine at idle then increase engine speed to 3000 RPM, if possible. Using scan tool, monitor DTC option. If this DTC fails this ignition cycle, go to next step. If this DTC does not fail this ignition cycle, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Turn ignition off. Disconnect throttle actuator harness connector. Turn ignition on, with engine off. Check voltage at both circuits of throttle actuator motor harness connector. If both circuits read greater than 8 volts, go to step 12 . If both circuits do not read greater than 8 volts, go to next step.
Turn ignition off. Check resistance on both throttle actuator motor harness connector circuits. If resistance is 0-5 ohms, go to step 10 . If resistance is not 0-5 ohms, go to next step.
Turn ignition off. Remove THROT CONT fuse. Check continuity from TAC side of fuse terminal to battery ground. If continuity exists, go to next step. If continuity does not exist, go to step 11 .
Disconnect TAC module harness connector. Check continuity from TAC side of fuse terminal to battery ground. If continuity exists, go to step 22 . If continuity does not exist, go to step 32 .
Disconnect TAC module harness connector. Check continuity from throttle actuator motor harness connector to battery ground. If continuity exists, go to step 23 . If continuity does not exist, go to step 32 .
Turn ignition off. Disconnect TAC harness connector. Check continuity between TAC side of fuse terminal to ignition feed circuit of TAC at harness connector. If continuity exists, go to step 32 . If continuity does not exist, go to step 24 .
Turn ignition off. Disconnect TAC module harness connector. Turn ignition on, with engine off. Check voltage at both circuits of throttle actuator motor harness connector. If both circuits read zero volts, go to next step. If both circuits do not read zero volts, go to step 25 .
Turn ignition off. Disconnect TAC module harness connector. Check continuity of both throttle actuator motor circuit to all other TAC module terminals. If continuity exists, go to step 30 . If continuity does not exist, go to next step.
Check continuity from TAC module ground circuit to battery ground. If continuity exists, go to next step. If continuity does not exist, go to step 26 .
Check voltage at serial data circuits in TAC module harness connector. If both serial data circuits read 0-4.5 volts, go to next step. If both serial data circuits do not read 0-4.5 volts, go to step 18 .
Turn ignition off. Check resistance from serial data circuits at TAC module harness connector to battery ground. If DVOM reads OL for both circuits, go to step 20 . If DVOM does not read OL for both circuits, go to next step.
Disconnect PCM harness connector. Check resistance from serial data circuits at TAC module harness connector to battery ground. If resistance is 0-5 ohms, go to step 27 . If resistance is not 0-5 ohms, go to next step.
Disconnect PCM harness connector. Check continuity of each serial data circuit between TAC module harness connector to PCM harness connector. If continuity is exists on either circuit, go to step 30 . If continuity does not exist on either circuit, go to next step.
Check voltage on both serial data circuits at TAC module harness connector. If voltage is indicated on either circuit, go to step 28 . If voltage is not indicated on either circuit, go to step 33 .
Disconnect PCM harness connector. Check continuity of each serial data circuit between TAC module harness connector and PCM harness connector. If continuity is indicated on both circuits, go to next step. If continuity is not indicated on both circuit, go to step 29 .
Reconnect PCM. Turn ignition on, with engine off. Check voltage at serial data circuit at TAC module harness connector. If voltage reading is zero volts, go to step 33 . If voltage reading is not zero volts, go to step 32 .
Repair TAC module ignition feed circuit for short to ground. After repairs, go to step 34 .
Repair throttle actuator motor circuit for short to ground. After repairs, go to step 34 .
Repair TAC module ignition feed circuit for an open in circuit. After repairs, go to step 34 .
Repair throttle actuator motor circuits for short to voltage. After repairs, go to step 34 .
Repair TAC module ground for open. After repairs, go to step 34 .
Repair serial data circuit for short to ground. After repairs, go to step 34 .
Repair serial data circuit for short to voltage. After repairs, go to step 34 .
Repair serial data circuit for an open in affected circuit. After repairs, go to step 34 .
Repair circuits that shows continuity. After repairs, go to step 34 .
Repair ignition feed circuit for short to voltage. After repairs, go to step 34 .
Replace TAC module. After replacing module, go to step 34 .
Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1519: TAC MODULE INTERNAL CIRCUIT (3.0L "V" BODY)

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

This DTC will run when Electronic Throttle Control (ETC) learn procedure is not active and duty cycle range switch is greater than 80 percent. DTC will set when ECM determines that it has an internal open or short to ground. ECM turns on MIL and records the operating conditions in the Freeze Frame data on the second consecutive drive trip that the diagnostic runs and fails. DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles in which there is no failure reported by this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1519: TAC MODULE INTERNAL CIRCUIT (3.8L "F" BODY)

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

TP sensor No. 1 signal is fed into a multiplexer (5X) to produce a high resolution calculated TP sensor voltage. This higher resolution TP sensor voltage is used for actuator control in low throttle angle conditions.

DTC will set when high resolution TP sensor is out of range for one second.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, review and record FAILURE RECORDS data and note parameters. Operate vehicle within FAILURE RECORDS conditions. Monitor SPECIFIC DTC INFO for this DTC. If scan tool indicates that this DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .
Replace TAC module. After replacing module, go to next step.
Using scan tool, select DTC option and clear DTCs. Warm engine to normal operating temperature. Using scan tool, select DTC and SPECIFIC DTC option, 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 .
Using scan tool, select CAPTURE INFO and REVIEW INFO options. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1520: PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT (4.0L "G" BODY)

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

The Park/Neutral Position (PNP) switch circuit is switched to ground in Park and Neutral. This test monitors the PNP switch for a false output. DTC will set if the switch is indicating Park or Neutral while driving conditions present indicate that transmission is in gear.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, observe Park/Neutral position parameter PNP, with vehicle in Park. If scan tool display reads P/N, go to next step. If scan tool display does not read P/N, go to step 7 .
Move shifter from Park through all the ranges and back to Park while observing the Park/Neutral position parameter. If scan tool display reads P/N all the time, go to step 5 . If scan tool display does not read P/N all the time, go to next step.
If scan tool display matches range selected, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool display does not match all the ranges selected, go to step 7 .
Disconnect PNP switch harness connector. If scan tool display reads P/N, go to next step. If scan tool display does not read P/N, go to step 9 .
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Using DVOM, check resistance between ground and PNP switch input circuit at harness connector terminal. If resistance is less than 10,000 ohms, go to step 8 . If resistance is not less than specified, go to step 10 .
Adjust PNP switch and shift lever.
Repair short to ground in PNP switch position input circuit.
Replace PNP switch.
Replace PCM. Program replacement PCM using required equipment.

Manipulate related wiring and connectors while observing transmission range switch input. If an intermittent is induced, the parameter display will change.

Attempt to crank engine while moving the shift lever. Since both the neutral safety and park/neutral switch contacts are housed together, an out of adjustment switch could cause an intermittent no-crank conditions.

Vehicle uses an electronic gear indicator display. The PCM uses the combination of the switch patterns to determine the gear selected by the vehicle operator. This information is then sent by serial data to the IPC for gear indicator display.

This test monitors the transaxle range switch for false inputs. DTC will set if the transaxle range switch is indicating a gear that the PCM does not recognize or the transaxle range switch input does not match the input of the transaxle pressure switch.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Ensure Park/Neutral switch and shift cable/lever are properly adjusted. Block drive wheels and apply parking brakes. Start engine. Move shift lever through each range and observe TRANS. RANGE and SEL. LEVER SW. in ENGINE 3 mode on scan tool. If scan tool displays match each other for the range selected, fault is not present. See «DIAGNOSTICS AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool display does not match the range selected, go to next step.
If only TRANS. RANGE display matches each range selected, go to next step. If range selected does not match TRANS. RANGE display, diagnose using transmission DTC P1810. See appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.
Turn ignition on, with engine off. Using scan tool in ENGINE 3 mode, observe SEL. LEVER SW A/B/C/P display. If all modes displays ON, go to step 13 . If not all of the modes displays ON, go to next step.
If any of the modes (A/B/C/P) stays on or off all of the time, regardless of selector position, go to next step. If only some of the modes stays on or off all the time regardless of selector position, go to step 15 .
If the mode(s) that did not change always display ON, go to step 9 . If it displays OFF, go to next step.
Store fluid life index as indicated on scan tool. Turn ignition to LOCK position and wait 30 seconds, then disconnect PCM harness connector C1 and transaxle range switch. Using DVOM, check resistance between ground and the circuit that were always off. Resistance should be 5 ohms. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, go to step 11 .
Repair short to ground on the affected circuits with low or no resistance.
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1 and transaxle range switch. Using DVOM, check resistance between the transaxle switch connector and PCM harness connector C1 terminals on the circuit(s) that were always on. Resistance should be 5 ohms. If resistance is greater than 5 ohms, go to next step. If resistance is not greater than 5 ohms, go to step 12 .
Repair open in the circuit(s) that have high or infinite resistance.
Reconnect PCM harness connector C1. Turn ignition on. Note SEL. LEVER SW A/B/C/P display on scan tool. If all the modes indicate ON, go to step 16 . If not all modes indicate ON, go to step 17 .
Reconnect PCM harness connector C1. Turn ignition on. Note SEL. LEVER SW A/B/C/P display on scan tool. Connect jumper wire between ground and the transaxle range switch harness connector terminal circuits that were always on. If scan tool display changes from ON to OFF when circuit is jumpered, go to step 15 . If scan tool display does not indicate a change from ON to OFF when circuit is jumpered, go to step 17 .
Turn ignition off. Disconnect transaxle range switch ground connector. Using DVOM, check resistance of ground connector to chassis ground. If resistance is 5 ohms or less, go to step 15 . If resistance is not 5 ohms or less, go to next step.
Repair open or high resistance in ground circuit to transaxle range switch.
Check terminal contact at transaxle range switch. Repair as necessary. If terminal contact is okay, go to next step.
Replace transaxle range switch.
Check terminal contact at PCM. Repair as necessary. If terminal is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

Check shifter for normal freedom of movement. The gear select indicator (PRNDL) in the IPC will flash on and off if an invalid or suspect gear position is received by the PCM. This will normally occur if the gear selector is not fully in a gear position. When a valid gear position is attained, the gear select display will immediately display the correct position. If the PRNDL on the IPC is flashing, this may be an indication that the shift cable and/or the transaxle range switch is out of adjustment.

On the scan tool, when checking the modes (circuits), OFF indicates that the circuit is low (switched/shorted to ground) and ON indicates that the circuit is high (open). The snapshot data provides valuable information in diagnosing an intermittent DTC P1520. If all digits of the transaxle range input are on, then check for an intermittent loss of ground to transaxle range switch. If an intermittent DTC P1520 occurs when the transaxle shift lever is moved, DTC is most likely caused by a misadjustment of the shift linkage or range switch, causing range switch to end up in the position between gears.

If DTC sets and PRNDL in the IPC is flashing while driving or when drive gear selector is not being moved, record the transaxle lever position and compare the values from the chart. (Scheme 11) This will determine if circuit is open, shorted or intermittent.

Scheme 11

Scheme 11: Diagnostic Aids

DTC P1523: TAC RETURN PERFORMANCE (3.0L "V" BODY)

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

This DTC will run when vehicle is not moving, engine speed is less than 250 RPM, ECT is 41-212°F (5-100°C) and IAT is greater than 41°F (5°C). DTC will set when ECM determines that the throttle valve is not in closed position. ECM will illuminate MIL and records the operating conditions in the Freeze Frame data on the second consecutive drive trip that the diagnostic runs and fails. DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles in which no failures are reported of this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Visually inspect throttle body. Ensure throttle valve is not binding or sticking. Depress and release throttle pedal several times while watching throttle valve. If throttle valve immediately returns to closed position when pedal is released, go to next step. If throttle valve does not immediately return to closed position when pedal is released, go to step 6 .
Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Using a test light connected to TP sensor 5-volt reference circuit, probe test light to TP sensor harness connector terminals No. 1, 3, 4, 5 and 6. If test light illuminates on any of these terminals, go to step 7 . If test light does not illuminate on any of these circuits, go to next step.
Turn ignition off. Using a DVOM, check resistance between TP sensor harness connector terminals No. 1, 2, 3, 4, 5 and 6. If resistance is infinite on any of the circuits, go to step 8 . If resistance is not infinite on any of the circuits, go to next step.
Replace throttle body assembly. After replacing throttle body, go to step 9 .
Repair sticking or binding throttle valve. After repairs, go to step 9 .
Repair short to ground in circuit that caused test light to illuminate. After repairs, go to step 9 .
Repair open circuit that had infinite resistance. After repairs, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1523: TAC RETURN PERFORMANCE (3.8L "F" BODY)

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

During battery saver mode, the Throttle Actuator Control (TAC) module determines if throttle plate is returning to correct de-energized position. If this fault is detected, the TAC module sends a message to the PCM through the serial data and this DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Check if any other DTCs are set. If other DTCs are set, diagnose affected DTC(s) first. If no other DTCs are set, go to next step.
Turn ignition off for 15 seconds. Turn ignition on, with engine off. Allow accelerator pedal to rest at idle stop for 20 seconds. Using scan tool, monitor INDICATED THROTTLE POSITION. If throttle position is 10.8-23.2 percent, go to step 6 . If throttle position is not 10.8-23.2 percent, go to next step.
Remove throttle body/TAC from intake. Check for obstructions preventing throttle blade to return to default position. If obstruction is present, go to next step. If no obstruction is present, go to step 6 .
Remove obstruction. After repairs, go to step 7 .
Replace throttle body/TAC assembly. After replacing throttle body, go to next step.
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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.

The Throttle Position (TP) sensor is self-adjusting. When ignition is turned off, PCM executes a TP sensor learn routine. If the same correction factor occurs on 2 consecutive key off cycles, TP sensor is corrected to zero degrees, using the correction factor learned. If the value needs correction by 6.8 degrees or greater, DTC will be stored in PCM memory at the next key on cycle.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on. Using scan tool, check if DTC P0121, P0122 or P0123 is present. If any of these DTC(s) are present, diagnose affected DTC(s) first. If these DTC(s) are not present, go to next step.
Select ENGINE 2 mode. Ensure foot is off accelerator pedal. Observe TP SENSOR display. If TP sensor reads 6.5 degrees or greater, go to step 5 . If TP sensor does not read 6.5 degrees or greater, go to next step.
If TP sensor reads less than -6.5 degrees, go to step 8 . If TP sensor does not read less than -6.5 degrees, go to next step.
Check for binding throttle and cruise control cables. Repair as necessary. After repairs, go to step 9 . If throttle and cruise control cables are okay, go to next step.
Check for deposits on throttle body bore and blades. Clean as necessary. After cleaning throttle body, go to step 9 . If throttle body did not need cleaning, go to next step.
Turn ignition on. Using scan tool, select ENGINE 2. Ensure foot is off accelerator pedal. Observe TP SENSOR display. If reading outside of a range of -6.5 to 6.5 degrees, go to next step. If reading is as specified, go to step 9 .
Replace throttle body. After replacing throttle body, go to next step.
Perform "TP Learn Procedure" as follows: turn ignition switch to LOCK position. Ensure throttle blade is fully closed and unobstructed. Turn ignition on. Wait 30 seconds. Turn ignition switch to LOCK position. After 30 seconds, repeat this step.

ECM will illuminate MIL and records the operating conditions in the Freeze Frame data on the second consecutive drive trip that the diagnostic runs and fails. DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles in which no failures are reported of this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
If any other DTCs are set, diagnose affected DTC(s). If no other DTCs are set, go to next step.
Visually inspect throttle body. Ensure throttle valve is in closed position. If throttle is closed, go to next step. If throttle valve is not closed, go to step 7 .
Using scan tool, monitor TP sensors No. 1 and No. 2 voltages. TP sensor No. 1 voltage should be.16-.80 volt. TP sensor No. 2 voltage should be 4.0-5.0 volts. If voltages are as specified, go to step 8 . If voltages are not as specified, go to next step.
Check TP sensors No. 1 and No. 2 circuit for open or short to ground. If circuit is faulty, go to next step. If circuit is okay, go to step 8 .
Repair as necessary. After repairs, go to step 9 .
Repair sticking or binding throttle valve. After repairs, go to step 9 .
Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing module, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

Ensure throttle motor is functioning properly.

DTC P1527: TRANSAXLE RANGE-TO-PRESSURE SWITCH COMPARISON (4.6L "E" & "K" BODIES)

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

An electronic gear indicator display is used. There are 4 inputs which are switches to ground, that each have a unique switch pattern. All 4 of these inputs are housed and operate together in the transaxle range switch. PCM uses the combination of the switch patterns to determine the gear selected by the driver. This information is then sent by serial data to the IPC for gear indicator display. This test compares the gear indicated by the transaxle range switch to the gear selected from the transmission fluid pressure manual valve position switch. If gear indicated is not the same for both, DTC will set.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Ensure P/N position switch and shift cable/lever are adjusted properly. Set parking brake and block drive wheels. Start engine. Move shift lever through each range and observe TFP switch (pressure) and transmission range on scan tool. If scan tool display matches each other for the range that is selected, fault is not present. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) . If scan tool display does not match each other for the range selected, go to next step.
If TFP switch matches each range selected, go to next step. If TFP switch does not match each range selected, go to step 17 .
Turn ignition on. Using scan tool, observe Trans Range A/B/C/P display. If all the modes display ON (high), go to step 13 . If modes does not display ON (high), go to next step.
If any of the modes (A/B/C/P) stay ON (high) or OFF (low) all the time regardless of selector position, go to next step. If modes does not stay ON or OFF all the time, go to step 15 .
If the mode(s) that did not change would always display ON (high), go to step 9 . If not, go to next step.
Store fluid life data. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector. Disconnect transaxle range switch. Using DVOM, check resistance between ground on the following circuit(s) that were always OFF (low): Mode "A" is circuit No. 771. Mode "B" is circuit No. 772. Mode "C" is circuit No. 773. Mode "P" is circuit No. 776. If resistance on tested circuit(s) is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, go to step 11 .
Repair short to ground in circuit(s) that have low or no resistance to ground.
Store fluid life data. Turn ignition off. Wait 30 seconds, then disconnect PCM harness connector. Disconnect transaxle range switch. Using DVOM, check resistance between transaxle range switch connector and PCM harness connector C1 terminals on the following circuit(s) that were always ON (high): Mode "A" is circuit No. 771. Mode "B" is circuit No. 772. Mode "C" is circuit No. 773. Mode "P" is circuit No. 776. If resistance on tested circuit(s) is greater than 5 ohms, go to next step. If resistance is not greater than 5 ohms, go to step 12 .
Repair open in circuit(s) that have high or infinite resistance.
Reconnect PCM harness connector (leave transaxle range switch disconnected). Turn ignition on. Check Trans Range A/B/C/P display. If all modes indicate ON (high), go to step 16 . If all modes does not indicate ON (high), go to step 23 .
Reconnect PCM harness connector (leave transaxle range switch disconnected). Turn ignition on. Check Trans Range A/B/C/P display. Using jumper wire, jumper transaxle range switch connector circuit that was always ON (high) to ground. If display changes from ON to OFF when circuit is jumpered, go to step 15 . If display does not change from ON to OFF when circuit is jumpered, go to step 23 .
Turn ignition off. Disconnect transaxle range switch ground connector. Check resistance to ground in circuit No. 451. If resistance is 5 ohms or less, go to step 15 . If resistance is not 5 ohms or less, go to next step.
Repair open or high resistance in circuit No. 451.
Check for 2 or more mode circuits shorted together. Repair as necessary. If circuit is okay, check terminal contact at transaxle range switch. If terminal contact is okay, go to next step.
Replace transaxle range switch.
If DTC P1810 is also present, diagnose using DTC P1810 test. If DTC P1810 is not present, go to next step.
Start engine. Check if Trans Range (pressure) match in P, R, N and D4, but not in D1, D2 and D3. If pressure matches, go to step 20 . If pressure does not match, go to next step.
Replace transmission fluid pressure manual valve position switch assembly.
Disconnect transaxle 20-pin harness connector. Shift through all gear ranges. If scan tool display ALWAYS indicate P/N, go to next step. If scan tool does not indicate P/N, go to step 22 .
Check transaxle range B input circuit between transaxle 20-pin harness connector and PCM for short to ground. Repair as necessary. If circuit is okay, go to step 23 .
Check for short to ground between transaxle 20-pin connector and transmission fluid pressure manual valve position switch or for a faulty fluid pressure manual valve position switch. Repair or replace as necessary.
Check terminal contact at PCM. Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

The modes (circuits) are displayed in the order of A/B/C/P. OFF indicates the circuit is low (switched/shorted to ground). ON indicates the circuit is high (open).

Manipulate related wiring and connectors while observing the transaxle range switch input. If an intermittent is induced, the digit corresponding the circuit will change. Use the Failure Records to help determine which switch was reading incorrectly. If the DTC set and the pressure switch indicated D1 and the select lever switch indicated P/N and the engine sensors (MAP, TP, MAF, etc.) appear to indicate that the vehicle was in Park or Neutral, then check the pressure switch/circuits for an intermittent fault.

The ECM will illuminate MIL and records the operating conditions in the Freeze Frame data on the second consecutive drive trip that the diagnostic runs and fails. DTC will clear when ECM turns off MIL after 3 consecutive drive trips that the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles in which no failures are reported of this diagnostic or any other emission related diagnostic. DTC will also clear when battery is disconnected or cleared by scan tool.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. After replacing ECM, go to next step.
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 that 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 .
Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, diagnose affected DTCs.

DTC P1533: A/C LOW SIDE TEMPERATURE SENSOR CIRCUIT (4.0L "G" BODY)

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

The A/C low side temperature sensor uses a thermistor to control the signal voltage to PCM. PCM applies 5 volts to A/C low temperature sensor circuit. When sensor is cold, sensor resistance is high and PCM will see a high signal voltage. As the sensor warms up, its resistance drops and signal voltage is pulled low through the ground circuit. This test detects a shorted to ground or open A/C low side temperature sensor circuit by setting DTC if the PCM monitors a signal voltage (temperature) that is too high or low.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool in ENGINE 3 mode, note A/C LOW SIDE TMP. display. If scan tool display reads -35 to 210°F (-37 to 99°C), fault is not present. Diagnose A/C-heater system. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. If scan tool display reads less than -35°F (-37°C) or greater than 210°F (99°C), go to next step.
If temperature displayed is less than -35°F (-37°C), go to next step. If temperature displayed is greater than -35°F (-37°C), go to step 7 .
Turn ignition off. Disconnect sensor harness connector. Using jumper wire, jumper A/C low temperature sensor harness connector terminals. Turn ignition on. If temperature reading is greater than 210°F (99°C), go to step 12 . If temperature reading is less than 210°F (99°C), go to next step.
Remove jumper wire from sensor harness connector. Jumper sensor harness connector terminal "A" to ground. If temperature reading is greater than 210°F (99°C), go to step 9 . If temperature reading is not greater than 210°F (99°C), go to next step.
Remove jumper wire from sensor connector. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Using DVOM, check resistance of A/C low temperature sensor signal circuit between PCM and sensor harness connector terminals. If resistance is greater than 5 ohms, go to step 10 . If resistance is not greater than 5 ohms, go to step 14 .
Disconnect sensor harness connector. If temperature displayed is less than -35°F (-37°C), go to step 12 . If temperature displayed is not less than -35°F (-37°C), go to next step.
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Using DVOM, check resistance between ground and A/C low temperature sensor circuit at PCM harness connector C1 terminal. If resistance is greater than 10,000 ohms, go to step 14 . If resistance is not greater than 10,000 ohms, go to next step.
Repair open in A/C low temperature sensor ground circuit.
Repair open in A/C low temperature sensor circuit.
Repair short to ground in A/C low temperature sensor circuit.
Check terminal contact at sensor harness connector. Repair as necessary. If terminal contact is okay, go to next step.
Replace A/C low temperature sensor.
Check terminal contact at PCM harness connector C1. Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

With engine not running and at ambient temperature, the A/C temperature sensor should be near ambient temperature. If A/C temperature sensor is not near ambient temperature, check for a sensor or circuit with resistance that is too high or too low. A sensor temperature reading that is too high would indicate a shorted or low resistance sensor or circuit. A sensor temperature that is too low would indicate an open or high resistance sensor or circuit.

DTC P1535: A/C HIGH SIDE TEMPERATURE SENSOR CIRCUIT (4.0L "G" BODY)

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

The A/C high side temperature sensor uses a thermistor to control the signal voltage to PCM. PCM applies 5 volts to A/C high temperature sensor circuit. When sensor is cold, sensor resistance is high and PCM will see a high signal voltage. As the sensor warms up, its resistance drops and signal voltage is pulled low through the ground circuit. This test detects a shorted to ground or open A/C high side temperature sensor circuit by setting DTC if the PCM monitors a signal voltage (temperature) that is too high or low.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Turn ignition on, with engine off. Using scan tool in ENGINE 3 mode, note A/C HI SIDE TMP. display. If scan tool reads 10-410°F (-12 to 210°C), fault is not present. Diagnose A/C-heater system. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. If scan tool display reads less than 10°F (-12°C) or greater than 410°F (210°C), go to next step.
If temperature displayed is greater than 410°F (210°C), go to step 7 . If temperature displayed is not greater than specified, go to next step.
Turn ignition off. Disconnect sensor harness connector. Using jumper wire, jumper A/C high temperature sensor harness connector terminals. Turn ignition on. If temperature reading is greater than 410°F (210°C), go to step 12 . If temperature reading is not greater than specified, go to next step.
Remove jumper wire from sensor harness connector. Jumper sensor harness connector terminal "A" to ground. If temperature reading is greater than 410°F (210°C), go to step 9 . If temperature reading is not greater than specified, go to next step.
Remove jumper wire from sensor connector. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Using DVOM, check resistance of A/C low temperature sensor signal circuit between PCM and sensor harness connector terminals. If resistance is greater than 5 ohms, go to step 10 . If resistance is not greater than 5 ohms, go to step 14 .
Disconnect sensor harness connector. If temperature displayed is less than 10°F (-12°C), go to step 12 . If temperature displayed is not less than 10°F (-12°C), go to next step.
Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C1. Using DVOM, check resistance between ground and A/C high temperature sensor circuit at PCM harness connector C1 terminal. If resistance is greater than 10,000 ohms, go to step 14 . If resistance is not greater than 10,000 ohms, go to next step.
Repair open in A/C high temperature sensor ground circuit.
Repair open in A/C high temperature sensor circuit.
Repair short to ground in A/C high temperature sensor circuit.
Check terminal contact at sensor harness connector. Repair as necessary. If terminal contact is okay, go to next step.
Replace A/C high temperature sensor.
Check terminal contact at PCM harness connector C1. Repair as necessary. If terminal contact is okay, go to next step.
Replace PCM. Program replacement PCM using required equipment.

DTC P1536: A/C SYSTEM ECT OVER-TEMPERATURE (4.0L "G" BODY)

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

This test monitors the ECT sensor for high engine temperature condition. If a high engine temperature condition exists, it will either disable the A/C compressor (if engaged) or will not allow compressor operation if requested. After the diagnostic test fails and is set current, it uses a lower temperature cut-off point to ensure that the A/C system will not be a load on the cooling system during conditions of high engine temperature.

Perform On-Board Diagnostic (OBD) system check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-introduction__on-board-diagnostic-obd-system-check) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
Using scan tool, check if DTC(s) P0116, P0117 or P1114 is also present. If any of these DTC(s) is present, diagnose affected DTC(s). If DTC(s) are not present, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/testing-diagnostics/#engine-control-system-tests-wcodes-dtc-p1273-p1536) .

This DTC is associated with an overheating/low coolant level condition. Diagnose cooling system.

Engine Control System - Tests W/codes - DTC p1273-p1536 Cadillac DeVille Concours I final

MODEL IDENTIFICATION

DTC P1273: APP SENSORS NO. 1 & 3 CORRELATION ERROR (3.8L "F" BODY)

Circuit Description

Diagnostic Procedures

Diagnostic Aids

DTC P1275: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (3.0L "V" BODY)

DTC P1275: APP SENSOR NO. 1 CIRCUIT (3.8L "F" BODY)

DTC P1275: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1276: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (3.8L "F" BODY)

DTC P1276: APP SENSOR NO. 1 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1280: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (3.0L "V" BODY)

DTC P1280: APP SENSOR NO. 2 CIRCUIT (3.8L "F" BODY)

DTC P1280: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1281: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (3.8L "F" BODY)

DTC P1281: APP SENSOR NO. 2 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1285: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (3.8L "F" BODY)

DTC P1285: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1286: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (3.8L "F" BODY)

DTC P1286: APP SENSOR NO. 3 CIRCUIT PERFORMANCE (5.7L "Y" BODY)

DTC P1320: IC MODULE 4X REFERENCE CIRCUIT INTERMITTENT (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1323: IC MODULE 24X REFERENCE CIRCUIT LOW FREQUENCY (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1336: CRANKSHAFT NOTCH ADAPTIVE NOT LEARNED (1.9L SATURN)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (2.2L "J" BODY, 2.2L "S" SERIES & 2.4L "J" & "N" BODIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.5L "W" BODY)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (3.8L "C", "F", "G" & "W" BODIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (4.8L, 5.3L & 6.0L "C" & "K" SERIES)

DTC P1336: CKP SYSTEM VARIATION NOT LEARNED (5.7L "F" BODY)

DTC P1345: CRANKSHAFT/CAMSHAFT POSITION SENSOR CORRELATION (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

DTC P1345: CRANKSHAFT/CAMSHAFT POSITION SENSOR CORRELATION (4.3L "C", "K", L", "M", "S" & "T" SERIES)

DTC P1350: IGNITION CONTROL (IC) SYSTEM (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1351: IGNITION CONTROL (IC) CIRCUIT OPEN (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1351: IGNITION CONTROL (IC) NO. 1 CIRCUIT OPEN (3.5L "W" BODY)

DTC P1351: IGNITION CONTROL (IC) CIRCUIT OPEN (3.8L "C", "F", "G", "H" & "W" BODIES)

DTC P1351: IGNITION CONTROL (IC) CIRCUIT HIGH VOLTAGE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

DTC P1351: IGNITION CONTROL (IC) CIRCUIT HIGH VOLTAGE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

DTC P1352: BY-PASS LINE OPEN (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1352: IGNITION CONTROL (IC) NO. 2 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

DTC P1352: BY-PASS CIRCUIT OPEN (3.8L "C", "F", "G", "H" & "W" BODIES)

DTC P1353: IGNITION CONTROL (IC) NO. 3 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

DTC P1354: IGNITION CONTROL (IC) NO. 4 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

DTC P1355: IGNITION CONTROL (IC) NO. 5 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

DTC P1356: IGNITION CONTROL (IC) NO. 6 CIRCUIT HIGH VOLTAGE (3.5L "W" BODY)

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1361: IGNITION CONTROL (IC) NO. 1 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.8L "C", "G", "H" & "W" BODIES)

DTC P1361: IGNITION CONTROL (IC) CIRCUIT NOT TOGGLING (3.8L "F" BODY)

DTC P1361: IGNITION CONTROL (IC) CIRCUIT LOW VOLTAGE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

DTC P1361: IGNITION CONTROL (IC) CIRCUIT LOW VOLTAGE (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)

DTC P1362: BY-PASS CIRCUIT SHORTED (3.1L "W" BODY & 3.4L "N" BODY & "U" SERIES)

DTC P1362: IGNITION CONTROL (IC) NO. 2 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1362: BY-PASS CIRCUIT SHORTED (3.8L "C", "F", "G", "H" & "W" BODIES)

DTC P1363: IGNITION CONTROL (IC) NO. 3 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1364: IGNITION CONTROL (IC) NO. 4 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1365: IGNITION CONTROL (IC) NO. 5 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1366: IGNITION CONTROL (IC) NO. 6 CIRCUIT LOW VOLTAGE (3.5L "W" BODY)

DTC P1370: IGNITION CONTROL (IC) MODULE 4X REFERENCE CIRCUIT TOO MANY PULSES (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1371: IGNITION CONTROL (IC) MODULE 4X REFERENCE CIRCUIT TOO FEW PULSES (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1372: IGNITION CONTROL (IC) SYSTEM OCCASIONAL RESYNC (3.5L "W" BODY)

DTC P1374: 3X REFERENCE CIRCUIT (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1374: 3X REFERENCE CIRCUIT (3.8L "C", "F", "G", "H" & "W" BODIES)

DTC P1375: IGNITION CONTROL (IC) MODULE 24X REFERENCE CIRCUIT HIGH VOLTAGE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1376: IGNITION GROUND CIRCUIT (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1377: IGNITION CONTROL (IC) MODULE CAM PULSE TO 4X REFERENCE PULSE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (2.2L & 2.4L "J" BODY & 2.2L "S" SERIES)

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1380: EBTCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.5L "W" BODY)

DTC P1380: EBTCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (3.8L "C", "F", "G", "H" & "W" BODIES)

DTC P1380: MISFIRE DETECTED - ROUGH ROAD DATA NOT AVAILABLE (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

DTC P1380: EBCM DTC DETECTED ROUGH ROAD DATA UNSTABLE (4.3L, 5.0L, 5.7L & 7.4L "C", "G" & "K" SERIES)

DTC P1381: MISFIRE DETECTED-NO EBCM/PCM SERIAL DATA (3.1L "N" & "W" BODIES & 3.4L "N" BODY & "U" SERIES)

DTC P1381: MISFIRE DETECTED-NO EBTCM/PCM SRI DATA (3.5L "W" BODY)

DTC P1381: MISFIRE DETECTED-NO EBCM/PCM SERIAL DATA (3.8L "C", "F", G", "H" & "W" BODIES)

DTC P1381: MISFIRE DETECTED-NO EBTCM/PCM SERIAL DATA (4.0L "G" BODY & 4.6L "E" & "K" BODIES)

DTC P1381: MISFIRE DETECTED-NO EBCM/VCM SERIAL DATA (4.3L "C", "K", "L", "M", "S" & "T" SERIES)

DTC P1381: MISFIRE DETECTED-NO EBCM/VCM SERIAL DATA (4.3L, 5.0L, 5.7L & 7.4L "C", "G", "K" & "P" SERIES)