Engine Control System - System Testing & Engine Component Tests: Diagnosis Saturn SL II

Diagnostic Aids

If boost control system check has been performed and no electrical or vacuum related fault is noted, check for misadjusted or sticking by-pass valve actuator, or binding by-pass valve or linkage. An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside insulation. Inspect PCM harness connector for backed-out terminals, improper mating, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness. To check for intermittent, disconnect PCM and install DVOM to monitor voltage between boost control solenoid control circuit at PCM connector and ground. With ignition on, observe voltage while manipulating related connectors and wiring harness. If failure is induced, voltage display will change. This may indicate location of fault.

MULTI-RAM SYSTEM DIAGNOSIS (3.0L)

Note. Powertrain Control Module (PCM) may also be referred to as Engine Control Module (ECM).

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Connect scan tool to Data Link connector (DLC). Retrieve DTCs. If DTCs P1112 or P1113 are not set, go to next step. If DTC P1112 or P1113 is set, perform appropriate diagnostic test. See appropriate SELF-DIAGNOSTICS article.
3. Visually inspect system. Check for disconnected or damaged vacuum hoses and/or components. Check linkage between vacuum actuators and valves for binding or interference with hoses. Ensure wiring is routed properly and not damaged. If problem does not exist, go to next step. If problem exists, repair as necessary and go to step 14 .
4. Start engine and observe vacuum actuator linkages for switchover valves. Using scan tool, command each valve ON and OFF. If both valves operate, go to next step. If either valve does not operate, go to step 6 .
5. Turn ignition off. Remove duct from between intake resonance switchover valve and throttle body. Hold throttle plates open to view moveable divider in back of intake manifold. Move actuator linkage by hand and ensure divider moves with linkage. Look down passages in intake resonance switchover valve to view moveable divider between 2 sides of valve. Move actuator linkage by hand to ensure divider moves with linkage. If both valves operate properly, system is okay. If either valve does not operate, go to step 13 .
6. Using scan tool, exit device control. Disconnect manifold vacuum supply hose at solenoid valve while observing actuator linkage. If actuator does not move when vacuum is disconnected, go to next step. If actuator moves when vacuum is disconnected, go to step 10 .
7. Check for vacuum at manifold vacuum supply hose. If vacuum exists, go to next step. If vacuum does not exist, go to step 11 .
8. Disconnect other hose from solenoid valve and connect hoses together using suitable vacuum connector. If actuator linkage does not operate, go to next step. If actuator linkage operates, go to step 10 .
9. Disconnect vacuum hose from actuator. If vacuum exists, go to step 13 . If vacuum does not exist, go to step 12 .
10. Replace solenoid valve. After repairs, go to step 14 .
11. Repair vacuum supply hose or plugged vacuum source. After repairs, go to step 14 .
12. Repair vacuum hose to actuator. After repairs, go to step 14 .
13. Replace valve/actuator assembly. After repairs, go to next step.
14. Start engine. Observe vacuum actuator linkages for switchover valves. Using scan tool, command each valve ON and OFF. If both valves operate, system is okay. If either valve does not operate, go to step 2 .

PCM OUTPUT DIAGNOSIS (2.2L & 2.4L)

1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
2. Turn ignition on, with engine off. Connect scan tool to Data Link connector (DLC). If a No. 1 is displayed below any of the number output drivers, go to next step. If a No. 1 is not displayed below any of the number output drivers, go to step 4 .
3. Disconnect electrical connector from component related to malfunctioning circuit. If a No. 1 is still displayed below corresponding output driver, go to step 6 . If a No. 1 is not displayed below any of the number output drivers, go to step 9 .
4. Using scan tool, command output being checked while watching corresponding position for that circuit. If that circuits position does not change to a No. 1, go to next step. If that circuits position changes to a No. 1, go to step 7 .
5. If component or function does not operate when commanded, go to step 9 . If component or function operates when commanded, go to step 11 .
6. Turn ignition off. Check for an open, short to voltage or short to ground in any corresponding circuit that indicated a No. 1 below output driver. Repair component or component circuit as necessary and go to step 11 . If circuits are okay, go to step 10 .
7. Disconnect electrical connector from component related to malfunctioning circuit. Using scan tool, command output being checked while watching corresponding position for that circuit. If a No. 1 is still displayed below corresponding output driver, go to next step. If a No. 1 is not displayed below any of the number output drivers, go to step 9 .
8. Turn ignition off. Check for an open, short to voltage or short to ground in any corresponding circuit that indicated a No. 1 below output driver. Repair component or component circuit as necessary and go to step 11 . If circuits are okay, go to step 10 .
9. Diagnose and repair any component that malfunctioned when commanded with scan tool. After repairs, go to step 11 .
10. Replace PCM. Program replacement PCM using required equipment. After repairs, go to next step.
11. Start engine and operate vehicle under condition under which original symptom was noted. If system does not operate properly, go to step 2 . If system operates properly, go to «DIAGNOSTIC AIDS»(ref-180-S04214453932000030800000) .

Scan tool has the ability to command certain components and functions ON and OFF. If a component or function does not have this capability, operate vehicle during normal function criteria to check for an open or shorted circuit. An open or short to ground will appear in the open positions of the scan tool only when it is not commanded by the PCM or scan tool. A short to voltage will appear in the short positions on the scan tool only while the component is being commanded by the PCM or scan tool.

Fuel Injector Circuit Diagnosis (5.7L)

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Start engine and let idle. Increase engine speed to 750 RPM. Using scan tool, monitor MISFIRE CUR. COUNTERS on MISFIRE DATA LIST (total of 8 counters, one per cylinder). If any MISFIRE CUR. COUNTERS are increasing, go to step 4 . If no MISFIRE CUR. COUNTERS are increasing, go to next step.
3. Monitor MISFIRE HIST. COUNTERS on MISFIRE DATA LIST. If any MISFIRE HIST. COUNTERS indicate a number other than zero, go to step 18 . If all MISFIRE HIST. COUNTERS indicate zero, check for intermittent. An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside insulation. Inspect PCM harness connector for backed-out terminals, improper mating, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness. When injector driver is disabled, an engine misfire will be apparent and a misfire DTC will set. Freeze frame and/or failure records data may also assist in locating an intermittent condition.
4. Check fuel injector ignition feed fuses. If all injector fuses are okay, go to next step. If any fuel injector fuse(s) is blown, go to step 8 .
5. Turn ignition off. Disconnect fuel injector harness connector that MISFIRE CUR COUNTER is increasing. Turn ignition on, leaving engine off. Using a test light connected to ground, probe ignition feed circuit (Pink wire) at appropriate fuel injector harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 10 .
6. Turn ignition off. Connect fuel injector test light to fuel injector harness connector. Start engine. If test light blinks, go to next step. If test light does not blink, go to step 11 .
7. Check for poor connection at fuel injector harness terminals. If a problem exists, repair as necessary and go to step 19 . If a problem does not exist, go to step 15 .
8. Turn ignition off. Disconnect the 4 fuel injector harness connectors related to fuse that was blown. Using a test light connected to battery voltage, probe one fuel injector ignition feed circuit (Pink wire). If test light does not illuminate, go to next step. If test light illuminates, go to step 13 .
9. Using DVOM, measure resistance of each fuel injector that is powered by blown fuse. If resistance is greater than 11.4 ohms at any fuel injector, go to step 14 . If resistance is 11.4 or less ohms at any fuel injector, go to step 15 .
10. Repair open in appropriate fuel injector ignition feed circuit (Pink wire). After repairs, go to step 19 .
11. Turn ignition off. Disconnect PCM harness connector C1. Check for an open or short to ground in fuel injector control circuits between PCM and fuel injector harness connectors. If problem exists, go to next step. If problem does not exist, go to step 16 .
12. Repair open or short to ground in fuel injector control circuit. After repairs, go to step 19 .
13. Repair short to ground in appropriate fuel injector ignition feed circuit. After repairs, go to step 19
14. Repair intermittent short to ground in appropriate fuel injector ignition feed circuit. After repairs, go to step 19
15. Replace faulty injector(s) as necessary. After repairs, go to step 19
16. Check for poor connections at PCM. If problem exists, repair as necessary and go to step 19 . If problem does not exist, go to next step.
17. Replace PCM. After repairs, go to step 19 .
18. Inspect appropriate injector circuit for poor connection at injector and PCM, intermittent short to ground, and intermittent opens. If problem exist, repair as necessary and go to step 19 . If problem does not exist, repair by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.
19. Using scan tool, clear DTCs. Start engine and let idle. Using scan tool, select DIAGNOSTIC TROUBLE CODE (DTC) option, and then SPECIFIC DTC option. Enter DTC and operate vehicle within conditions for running the DTC. If scan tool indicates DTC ran and passed, go to next step. If scan tool does not indicate DTC ran and passed, go to step 2 .
20. Using scan tool, select CAPTURE INFO option, and then REVIEW INFO option. If no DTCs are set, system is okay. If any DTCs are set, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article.

Fuel Injector Balance Test

Note. Allow engine to cool down to avoid irregular readings due to "hot soak" fuel boiling. To prevent flooding, the fuel injector balance test should not be performed more than once without starting and running engine.

Note. If injectors are dirty, they should be cleaned using approved injector cleaning procedure before performing fuel injector balance test.

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. If fuel injector coil test has been performed, go to next step. If fuel injector coil test has not been performed, perform fuel injector coil test. See «INJECTOR COIL TEST - ECT BETWEEN 50-95°F»(ref-180-S28923332322000030800000) .
3. If engine coolant temperature is less than 201°F (94°C), go to step 5 . If engine coolant temperature is greater than 201°F (94°C), go to next step.
4. Allow engine to cool until coolant temperature is less than 201°F (94°C), then go to next step.
5. Install fuel pressure gauge. Turn ignition on, and then off. Bleed air from fuel pressure gauge. Using scan tool, energize fuel pump. Observe fuel pressure gauge reading. See «FUEL PUMP PRESSURE»(ref-180-S12863776872000030800000) table. If fuel pressure reading is within specification, go to next step. If fuel pressure reading is not within specification, perform fuel system diagnosis. See appropriate BASIC DIAGNOSTIC PROCEDURES article.
6. Turn fuel pump off. Observe fuel pressure gauge. If fuel pressure remains constant, go to next step. If fuel system does not remain constant, perform fuel system diagnosis. See appropriate BASIC DIAGNOSTIC PROCEDURES article.
7. Disconnect fuel injectors harness connector. Using appropriate fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Balance Test 2.5-amp position. Turn ignition on, and then off. Record fuel pressure reading (first reading). Energize injector by depressing PUSH TO START TEST button on injector tester and hold until fuel pressure gauge stabilizes. Record fuel pressure reading (second reading). Subtract first reading from second reading (this result is pressure drop value). Add pressure drop value for each injector together and divide total by total number of injectors. If any injector's drop value is greater or less than average drop value by 1.5 psi, replace faulty injector(s) as necessary. If no injector's drop value is greater or less than average drop value by 1.5 psi, repair by symptom. See appropriate TROUBLE SHOOTING - NO CODES article.

FUEL PUMP PRESSURE

Injector Coil Test - ECT Between 50-95°F

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Using scan tool, check engine coolant temperature. If scan tool displays 50-95°F (10-35°C), go to next step. If scan tool does not display 50-95°F (10-35°C), perform injector coil test. See «INJECTOR COIL TEST - ECT NOT BETWEEN 50-95°F»(ref-180-S00637535942000030800000) .
3. Turn ignition off. Relieve fuel pressure. Disconnect fuel injector harness connectors. Using appropriate fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Coil Test 0.5-amp position. Connect DVOM to fuel injector tester. Depress PUSH TO START TEST button on injector tester. Record lowest voltage reading within first second of test. If any injector has erratic voltage reading or reading not 5.7-6.6 volts (4.7-5.8 volts on 2.2L and 2.4L with EGR engines, or 8.0-8.5 volts on 3.0L engine), go to next step. If no injector has erratic voltage reading or reading not 5.7-6.6 volts (4.7-5.8 volts on 2.2L and 2.4L with EGR engines, or 8.0-8.5 volts on 3.0L engine), perform fuel injector balance test. See «FUEL INJECTOR BALANCE TEST»(ref-180-S24651399782000030800000) .
4. Replace faulty injector(s) and perform fuel injector balance test. See «FUEL INJECTOR BALANCE TEST»(ref-180-S24651399782000030800000) .

Injector Coil Test - ECT Not Between 50-95°F

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Using scan tool, check engine coolant temperature. If scan tool does not displays 50-95°F (10-35°C), go to next step. If scan tool displays 50-95°F (10-35°C), perform injector coil test. See «INJECTOR COIL TEST - ECT BETWEEN 50-95°F»(ref-180-S28923332322000030800000) .
3. Turn ignition off. Relieve fuel pressure. Disconnect fuel injector harness connectors. Using fuel injector adapter, connect Fuel Injector Tester (J-39021) to fuel injector. Connect fuel injector tester power leads to appropriate battery terminals. Set amperage supply selector switch on fuel injector tester to Coil Test 0.5-amp position. Connect DVOM to injector tester. Depress PUSH TO START TEST button on injector tester. Record highest voltage reading other than those greater than 9.5 volts. Subtract any other voltage reading observed from highest voltage reading. If difference is greater than 0.6 volt (0.7 volt on 2.2L and 2.4L), go to next step. If difference is not greater than 0.6 volt (0.7 volt on 2.2L and 2.4L), perform fuel injector balance test. See «FUEL INJECTOR BALANCE TEST»(ref-180-S24651399782000030800000) .
4. Replace any injector(s) that had any of the following results: initial reading greater than 9.5 volts, erratic reading or difference is greater than 0.6 volt (0.7 volt on 2.2L and 2.4L). After repairs, perform fuel injector balance test. See «FUEL INJECTOR BALANCE TEST»(ref-180-S24651399782000030800000) .

Injector Leak Test (1.9L)

1. Disconnect negative battery terminal. Remove air intake tube and resonator. Install Fuel Gauge Bar Kit (SA9127E) to fuel pressure test port. Bleed system pressure through bleed hose.
2. Disconnect fuel pressure regulator vacuum hose. Remove fuel lines from bracket, leaving fuel supply lines attached to fuel rail assembly and connectors. Disconnect and plug fuel return line from fuel rail.
3. Remove fuel rail assembly retaining bolts. Pull fuel rail back far enough that injector nozzles are visible but still in intake ports. Secure fuel rail to intake manifold with wire.
4. Wipe off any fuel or debris from fuel injector tips. Place a clean, White towel directly under fuel injectors, with towel lightly touching each fuel injector tip to easily spot a leaky injector.
5. Reconnect negative battery terminal. Ensure battery is fully charged. Cycle ignition on and off several times. DO NOT start engine. Observe fuel injector tips for 5 minutes. Fuel rail pressure should be about 46 psi (3.23 kg/cm 2 ) with fuel rail return line plugged. Run test at least twice. Replace any leaky fuel injector.
6. Bleed fuel pressure through bleed hose and remove fuel pressure gauge. Reinstall fuel rail, fuel return line and pressure regulator vacuum hose. Lubricate injector "O" rings and male end of steel line with clean engine oil prior to installation. Start engine and check for fuel leaks.

EVAP Control System Diagnosis (2.2L & 2.4L)

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Install scan tool. Turn ignition on, with engine off. Retrieve DTCs. If no DTCs are set, go to next step. If any DTCs are set, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article.
3. Using scan tool, command EVAP canister purge valve and EVAP canister vent solenoid on and off. If both purge valve and vent solenoid click when toggled on and off, go to next step. If either purge valve or vent solenoid do not click when toggled on and off, perform PCM output diagnosis. See «PCM OUTPUT DIAGNOSIS (2.2L & 2.4L)»(ref-180-S01476860542000030800000) under COMPUTERIZED ENGINE CONTROLS.
4. Turn ignition off. Disconnect vapor line from fuel tank at EVAP canister. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure. If scan tool displays -1.28-1.28 in. H 2 O, go to next step. If scan tool does not display -1.28-1.28 in. H 2 O, perform DTC P0452 or DTC P0453 test. See appropriate SELF-DIAGNOSTICS article.
5. Reconnect vapor line from fuel tank to EVAP canister. Install EVAP Pressure/Purge Diagnostic Station (J-41413) to EVAP service port and zero gauges. Using scan tool, command EVAP vent solenoid on. Using diagnostic station, pressurize EVAP system to 5 in. H 2 O. Using scan tool, observe fuel tank pressure. If scan tool displays 3.85-8.99 in. H 2 O, go to next step. If scan tool does not display 3.85-8.99 in. H 2 O, perform DTC P0452 or DTC P0453 test. See appropriate SELF-DIAGNOSTICS article.
6. Observe EVAP system pressure on diagnostic station. Using scan tool, command EVAP canister vent solenoid off. If EVAP system pressure decreases to zero in. H 2 O within 5 seconds, go to next step. If EVAP system pressure does not decrease to zero in. H 2 O within 5 seconds, perform DTC P0446 test. See appropriate SELF-DIAGNOSTICS article.
7. Disconnect vapor line from fuel tank at EVAP canister. Start engine. Using scan tool output test function, select SEAL SYSTEM and seal EVAP system. Reconnect vapor line from fuel tank to EVAP canister. Increase engine speed to 1500 RPM. Using scan tool, observe fuel tank pressure. If fuel tank pressure does not decrease, go to next step. If fuel tank pressure is decreasing, perform DTC P1441 test. See appropriate SELF-DIAGNOSTICS article.
8. Using scan tool, command EVAP canister vent solenoid and EVAP canister purge valve on. Increase engine speed to 1500 RPM. Using scan tool, observe fuel tank pressure. If fuel tank pressure is decreasing, system is okay. If fuel tank pressure does not decrease, perform DTC P0440 test. See appropriate SELF-DIAGNOSTICS article.

EVAP Control System Diagnosis (3.1L, 3.4L & 3.8L)

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Check for disconnected vacuum or purge lines, or a loose or missing fuel filler cap. Install scan tool. Turn ignition on, with engine off. Retrieve DTCs. If no DTCs are set, go to next step. If any DTCs are set, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article.
3. Turn ignition off. Disconnect canister purge line from EVAP canister purge valve. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H 2 O, go to next step. If fuel tank pressure is not zero in. H 2 O, go to step 10 .
4. Turn ignition off. Reconnect canister purge line to EVAP canister purge valve. Install EVAP Pressure/Purge Diagnostic Station (J-41413) to EVAP service port and zero gauges. Turn ignition on, with engine off. Using scan tool, command EVAP canister vent solenoid on. Using diagnostic station, pressurize EVAP system to 5 in. H 2 O while observing fuel tank pressure on scan tool. If fuel tank pressure is 5 in. H 2 O, go to next step. If fuel tank pressure is not 5 in. H 2 O, perform DTC P0440 test. See appropriate SELF-DIAGNOSTICS article.
5. Monitor EVAP pressure gauge on diagnostic station while maintaining fuel tank pressure at 5 in. H 2 O. Using scan tool, observe fuel tank pressure. If fuel tank pressure is 5 in. H 2 O, go to next step. If fuel tank pressure is not 5 in. H 2 O, go to step 11 .
6. Monitor EVAP pressure gauge on diagnostic station while commanding EVAP canister vent solenoid off using scan tool. If EVAP pressure gauge decreases to near -5 in. H 2 O within 2 minutes, go to next step. If EVAP pressure gauge does not decrease to near -5 in. H 2 O within 2 minutes, perform DTC P0446 test. See appropriate SELF-DIAGNOSTICS article.
7. Connect the in. Hg gauge of diagnostic station to purge valve canister side. Turn ignition on, with engine off. Using scan tool output test function, select SEAL SYSTEM and seal EVAP system. Start and idle engine. Increase engine speed to 1200-1500 RPM and observe vacuum gauge on diagnostic station. If vacuum increases to greater than zero in. Hg, go to next step. If vacuum does not increase to greater than zero in. Hg, go to step 12 .
8. Using scan tool, increase purge to 100 percent. Run engine at 1200-1500 RPM while monitoring vacuum gauge on diagnostic station. If vacuum increases to greater than 15 in. Hg, go to step 14 . If vacuum does not increase to greater than 15 in. Hg, go to step 13 .
9. Turn ignition off. Disconnect EVAP canister line from fuel tank or EVAP canister. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure. If fuel tank pressure is zero in. H 2 O, go to next step. If fuel tank pressure is not zero in. H 2 O, perform DTC P0453 test. See appropriate SELF-DIAGNOSTICS article.
10. Check for kinked or restricted canister purge line between EVAP canister purge valve and EVAP canister and repair as necessary. After repairs, go to step 14 .
11. Check for restricted fuel tank vapor line or EVAP purge line. If problem exists, repair as necessary and go to step 14 . If problem does not exist, perform DTC P0452 test. See appropriate SELF-DIAGNOSTICS article.
12. Check for no source vacuum to EVAP purge valve. After repairs, go to step 14 .
13. Check for carbon release into EVAP system. Locate and repair cause of no source vacuum to EVAP purge valve. If problem exists, repair as necessary and go to step 14 . If problem does not exist, go to step 12 .
14. Reconnect all previously disconnected EVAP components. Turn ignition on, with engine off. Using scan tool output test function, select SEAL SYSTEM and seal EVAP system. Using diagnostic station, apply 15 in. H 2 O pressure to EVAP system. If EVAP pressure gauge does not decrease to 10 in. H 2 O within 2 minutes, system is okay. If EVAP pressure gauge decreases to 10 in. H 2 O within 2 minutes, perform DTC P0446 test. See appropriate SELF-DIAGNOSTICS article.

Fuel Tank Pressure Sensor Diagnosis (3.1L & 3.8L)

1. If On-Board Diagnostic (OBD) system check has been performed, go to next step. If On-Board Diagnostic (OBD) system check has not been performed, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
2. Disconnect fuel tank pressure sensor harness connector. Using DVOM, measure voltage between reference voltage circuit (Gray wire) and ground circuit (Orange/Black wire on 3.1L; Black wire on 3.8L) at fuel tank pressure sensor harness connector. If voltage is not about 5 volts, go to next step. If voltage is about 5 volts, go to step 5 .
3. Check fuel tank pressure sensor reference voltage circuit (Gray wire) for poor connection at PCM. If problem does not exist, go to next step. If problem exists, go to step 11 .
4. Check for an open in fuel tank pressure sensor reference voltage circuit (Gray wire) between PCM and fuel tank pressure sensor harness connector. If problem does not exist, go to step 8 . If problem exists, go to step 12 .
5. Remove fuel filler cap. Connect 2 fused jumper wires between reference voltage circuit (Gray wire) and ground circuit (Orange/Black wire on 3.1L; Black wire on 3.8L) between fuel tank pressure sensor pigtail and fuel tank pressure sensor harness connector. Using DVOM, measure voltage at signal circuit (Dark Green wire) of fuel tank pressure sensor pigtail. If voltage is 1.3-1.7 volts, go to next step. If voltage is not 1.3-1.7 volts, go to step 13 .
6. Check fuel tank pressure sensor signal circuit (Dark Green wire) for poor connection at PCM. If problem does not exist, go to next step. If problem exists, go to step 11 .
7. Check fuel tank pressure sensor signal circuit (Dark Green wire) for open, short to voltage or short to ground between PCM and fuel tank pressure harness connectors. If problem exists, go to step 12 . If problem does not exist, go to step 14 .
8. Check fuel tank pressure sensor ground circuit (Orange/Black wire on 3.1L; Black wire on 3.8L) for poor connection at PCM. If problem does not exist, go to next step. If problem exists, go to step 11 .
9. Check fuel tank pressure sensor ground circuit (Orange/Black wire on 3.1L; Black wire on 3.8L) for open between PCM and fuel tank pressure harness connectors. If problem exists, go to step 12 . If problem does not exist, go to step 14 .
10. Check for poor connection at fuel tank pressure sensor. If problem exists, go to next step. If problem does not exist, go to step 13 .
11. Repair poor terminal connections as necessary. After repairs, go to step 15 .
12. Repair open or short circuit in wiring as necessary. After repairs, go to step 15 .
13. Replace fuel tank pressure sensor. After repairs, go to step 15 .
14. Replace PCM. After repairs, go to next step.
15. Turn ignition off. Remove fuel cap. Install scan tool. Turn ignition on. Using scan tool, observe fuel tank pressure. If scan tool displays zero in. H 2 O, go to next step. If scan tool does not display zero in. H 2 O, go to step 2 .
16. Replace fuel cap. Install EVAP Pressure/Purge Diagnostic Station (J-41413) to EVAP service port. Using scan tool, command EVAP canister vent solenoid on. Using diagnostic station, pressurize EVAP system to 5 in. H 2 O. Using scan tool, observe fuel tank pressure. If scan tool displays 5 in. H 2 O, system is okay. If scan tool does not display 5 in. H 2 O, go to step 2 .