Engine Controls - System & Component Testing: Diagnosis Pontiac Aztek I

Circuit Description

The ignition relay is normally an open relay. The relay armature is held in the open position by spring tension. When the ignition switch is turned to the RUN or START position, current will flow through the relay coil. A wire connected to the other end of the relay coil completes the path to ground. The electromagnetic field created by the relay coil overcomes the spring tension and moves the armature, allowing the relay contacts to close.

The closed relay contacts allow current to flow from the battery to the ENG CONTROLS fuse, Fuel INJ fuse, ELEC ENG fuse, O2 Sensors fuse, TRANS SOL fuse, ABS fuse and AWD fuse. Fuses are located in underhood fuse/relay block. (Scheme 5)

When the ignition switch is turned off, the electromagnetic field collapses. This action allows the spring tension to move the armature away from the relay contacts, which interrupts current flow to the fuses.

If ignition relay fails to close, the engine will crank but will not run. The class 2 communications will be available with the use of a scan tool.

Scheme 5

Diagnostic Procedures

1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing diagnostic system check, go to next step.
2. Turn ignition on, with engine off. Remove the underhood junction block cover. Probe the following fuses with a test light that is connected to a good ground; ENG CONTROLS fuse, FUEL INJ fuse, ELEC ENG fuse, O2 SENSORS fuse, TRANS SOL fuse, ABS fuse and AWD fuse. (Scheme 5) Does the test light illuminate on at least one test point of each fuse? If yes, go to next step. If no, go to step 11.
3. Turn ignition off. Probe both test points of the FUEL INJ fuse with a test light that is connected to a good ground. Does the test light illuminate on either test point of the fuse? If yes, go to next step. If no, go to step 43.
4. Turn ignition off. Remove ignition relay from the underhood junction block. Probe both test points of the 10-amp IGN 1 fuse in the underhood junction block with a test light connected to a good ground. Does the test light illuminate on any of the fuse test points? If yes, go to step 7. If no, go to next step.
5. Test the ignition relay load circuit bus bar of the underhood junction block between the ignition relay and the fuses to the circuit components for a short to battery positive voltage. Did you find and correct the condition? If yes, go to step 42. If no, go to next step.
6. Turn ignition off. Remove the following fuses from the underhood junction block: ENG CONTROLS fuse, FUEL INJ fuse, ELEC ENG fuse, O2 SENSORS fuse, TRANS SOL fuse, ABS fuse and AWD fuse. Probe all these fuse terminals in the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate at any of the fuse terminals? If yes, diagnose engine electrical system. If no, go to step 39.
7. Turn ignition off. Disconnect the ignition switch electrical connector. Connect a 20-amp fused jumper wire from the battery positive voltage wire terminal at the ignition switch harness connector to the battery positive voltage terminal at the ignition switch. Probe the ignition 1 voltage terminal of the ignition switch with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 40. If no, go to next step.
8. Turn ignition off. Disconnect negative battery cable at the battery. Disconnect the console junction block electrical connector that contains the ignition 1 voltage circuit from the ignition switch. Connect the negative battery cable to the battery. Probe the ignition 1 voltage circuit between the ignition switch and the console junction block at the console junction block electrical connector with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 35. If no, go to next step.
9. Turn ignition off. Disconnect negative battery cable at the battery. Disconnect the underhood junction block electrical connector that contains the ignition 1 voltage circuit for the ignition relay. Connect the negative battery cable to the battery. Probe the ignition 1 voltage circuit of the ignition relay at the underhood junction block electrical connector with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 38. If no, go to next step.
10. Test the ignition 1 voltage bus bar circuit for the ignition relay in the console junction block for a short to battery positive voltage. Did you find a condition? If yes, go to step 41. If no, go to step 42.
11. Turn ignition off. Probe both test points of the 20-amp IGN 3 fuse in the underhood junction block with a test light that is connected to a good ground. (Scheme 5) Does the test light illuminate on both test points of the fuse? If yes, go to step 19. If no, go to next step.
12. Does the test light illuminate on one test point of the 20-amp IGN 3 fuse? If yes, go to next step. If no, go to step 28.
13. Test the battery positive voltage circuit between the underhood junction block and the ignition switch for a short to ground. Did you find and correct the condition? If yes, go to step 43. If no, go to next step.
14. Test the ignition 1 voltage circuit between the ignition switch and the console junction block for a short to ground. Did you find and correct the condition? If yes, go to step 43. If no, go to next step.
15. Test the ignition 1 voltage circuit between the console junction block and the underhood junction block for a short to ground. Did you find and correct the condition? If yes, go to step 43. If no, go to next step.
16. Test the ignition 1 voltage bus bar circuit of the console junction block between the ignition switch and the underhood junction block for a short to ground. Did you find a condition? If yes, go to step 41. If no, go to next step.
17. Test the ignition 1 voltage bus bar circuit of the underhood junction block up to the 10-amp IGN 1 fuse for a short to ground. Did you find a condition? If yes, go to step 42. If no, go to next step.
18. Test the battery positive voltage bus bar circuit of the underhood junction block from the 20-amp IGN 3 fuse for a short to ground. Did you find a condition? If yes, go to step 42. If no, go to step 40.
19. Turn ignition on, with engine off. Probe both test points of the 10-amp IGN 1 fuse in the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate on both test points of the fuse? If yes, go to step 29. If no, go to next step.
20. Does the test light illuminate on one test point of the 10-amp IGN 1 fuse? If yes, go to step 27. If no, go to next step.
21. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit at the ignition switch electrical connector with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 24. If no, go to next step.
22. Test the battery positive voltage circuit between the underhood junction block and the ignition switch for a high resistance or an open. Did you find and correct a condition? If yes, go to step 43. If no, go to next step.
23. Turn ignition off. Probe the mounting stud for the battery positive terminal at the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 40. If no, diagnose engine electrical system.
24. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit for the ignition relay at the console junction block electrical connector that leads from the ignition switch with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 36.
25. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit for the ignition relay at the console junction block electrical connector that leads to the underhood junction block with a test light that is connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step 41.
26. Turn ignition off. Disconnect the negative battery cable at the battery. Disconnect the underhood junction block electrical connector that contains the ignition 1 voltage circuit for the ignition relay. Connect the negative battery cable at the battery. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit at the underhood junction block electrical connector with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 42. If no, go to step 37.
27. Test the ignition 1 voltage bus bar circuit of the underhood junction block between the 10-amp IGN 1 fuse and the ignition relay for a short to ground. Did you find a condition? If yes, go to step 42. If no, go to step 39.
28. Turn ignition off. Probe the mounting stud for the battery positive cable at the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to step 42. If no, diagnose engine electrical system.
29. Turn ignition off. Remove the ignition relay with the J 43244 from the underhood junction block. Probe the battery positive voltage circuit of the ignition relay at the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 42.
30. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit of the ignition relay at the underhood junction block with a test light that is connected to a good ground. Does the test light illuminate? Is yes, go to next step. If no, go to step 42.
31. Turn ignition on, with engine off. Probe the coil ground circuit of the ignition relay at the underhood junction block with a test light that is connected to battery voltage. Does the test light illuminate? If yes, go to step 33. If no, go to next step.
32. Turn ignition off. Disconnect the negative battery cable at the battery. Disconnect the underhood junction block electrical connectors. Test the coil ground circuit wire of the ignition relay at the underhood junction block electrical connector for a high resistance or an open. Did you find and correct the condition? If yes, go to step 43. If no, go to step 42.
33. Turn ignition off. Jumper the ignition relay battery positive voltage circuit and the ignition relay load circuit together at the underhood junction block with a 20-amp fused jumper wire. Probe the following fuses with a test light that is connected to a good ground: ENG CONTROLS fuse, FUEL INJ fuse, O2 SENSORS fuse, TRANS SOL fuse, ABS fuse and AWD fuse. Does the test light illuminate on at least one test point of each fuse? If yes, go to next step. If no, go to step 42.
34. Test for an intermittent and for a poor connection at the underhood junction block, ignition relay connector location. Did you find a condition? If yes, go to step 42. If no, go to step 39.
35. Repair the short to battery positive voltage in the ignition 1 voltage circuit between the ignition switch and the console junction block. After repairs, go to step 43.
36. Repair the high resistance or an open in the ignition 1 voltage circuit between the console junction block and the ignition switch. After repairs, go to step 43.
37. Repair the high resistance or an open in the ignition 1 voltage circuit between the console junction block and the underhood junction block. After repairs, go to step 43.
38. Repair the short to battery positive voltage in the ignition 1 voltage circuit between the console junction block and the underhood junction block electrical connector. After repairs, go to step 43.
39. Replace ignition relay. After replacing relay, go to step 43.
40. Replace ignition switch. After replacing ignition switch, go to step 43.
41. Replace console junction block. After replacing junction block, go to step 43.
42. Replace the underhood junction center. After replacing junction center, go to next step.
43. Replace any open fuses. Turn ignition off for 30 seconds. Attempt to start the engine. Does the engine start and run? If yes, go to next step. If no, go to «NO-START - ENGINE CRANKS OKAY»(ref-152619-S06368399132003021700000) under NO-START in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
44. Using scan tool, clear DTCs. Operate the vehicle for 5 minutes. Does a DTC set during this ignition cycle? If yes, diagnose affected DTC(s). See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-155075-S27919636112003060600000) in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. If no DTCs are set, system is okay.

Diagnostic Procedure

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Perform «FUEL INJECTOR COIL TEST»(ref-153136-S02728456852003031900000). After performing Fuel Injector Coil Test, go to next step.
3. Observe ECT parameter with scan tool. Does scan tool indicate ECT parameter is less than 201°F (94°C)? If yes, go to next step. If no, allow engine to cool before proceeding.
4. Turn ignition off. Turn off all accessories. Install fuel pressure gauge. Turn ignition on, with engine off. Command fuel pump ON with scan tool. Observe fuel pressure gauge, with fuel pump commanded ON. Is fuel pressure within 52-59 psi (358-405 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM PRESSURE TEST»(ref-152619-S29857367862003021700000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
5. Monitor fuel pressure gauge for one minute. Does fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to «FUEL SYSTEM PRESSURE TEST»(ref-152619-S29857367862003021700000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article. If no, go to next step.
6. Connect Fuel Injector Coil/Balance Tester (J-39021), Injector Test Adapter Box (J-39021-210), and Fuel Injector Test Harness (J-39021-410) to fuel injector multi-way connector. Set amperage supply selector switch on fuel injector tester to Balance Test.5-2.5-amp position. Command fuel pump ON and then OFF with scan tool. Record fuel pressure indicated by fuel pressure gauge after fuel pressure stabilizes. This is first pressure reading. Energize fuel injector by depressing "Push to Start Test" button on fuel injector tester. Record fuel pressure indicated by fuel pressure gauge after fuel injector has stopped pulsing. This is second pressure reading. Repeat this step for each fuel injector. Subtract second pressure reading from first pressure reading for one fuel injector. Result is pressure drop value. see scheme 19 Obtain a pressure drop value for each fuel injector. Add all individual pressure drop values. This is total pressure drop. Divide total pressure drop by number of fuel injectors. This is average pressure drop. Does any fuel injector have a pressure drop value more than average pressure drop or less than average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOMS»(ref-152915-S31711482542003030500000) in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
7. Replace affected fuel injectors. After repairs, go to next step.
8. Operate system in order to verify repair. Does a driveability condition still exist? If yes, go to «SYMPTOMS»(ref-152915-S31711482542003030500000) in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, system is okay.

Scan tool first energizes fuel pump and then injectors for a precise amount of time allowing a measured amount of fuel into manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Perform «FUEL INJECTOR COIL TEST»(ref-153136-S02728456852003031900000) . After performing Fuel Injector Coil Test, go to next step.
3. Observe ECT parameter with scan tool. Does scan tool indicate ECT parameter is less than 201°F (94°C)? If yes, go to next step. If no, allow engine to cool before proceeding.
4. Turn ignition off. Turn off all accessories. Install fuel pressure gauge. Turn ignition on, with engine off. Command fuel pump ON with scan tool. Observe fuel pressure gauge, with fuel pump commanded ON. Is fuel pressure within 52-59 psi (358-405 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM PRESSURE TEST»(ref-152619-S29857367862003021700000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.
5. Monitor fuel pressure gauge for one minute. Does fuel pressure decrease by more than 5 psi (34 kPa)? If yes, go to «FUEL SYSTEM PRESSURE TEST»(ref-152619-S29857367862003021700000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article. If no, go to next step.
6. With scan tool, select Fuel Injector Balance Test function, within Special Functions menu. Select an injector to be tested. Press Enter. This will prime fuel system. Record fuel pressure indicated by fuel pressure gauge after fuel pressure stabilizes. This is first pressure reading. Energize fuel injector by depressing Pulse Injector button on scan tool. This will energize injector and decrease fuel pressure. Record fuel pressure indicated by fuel pressure gauge after fuel injector has stopped pulsing. This is second pressure reading. Press Enter again to bring you back to Select Injector screen. Repeat this step for each fuel injector. Subtract second pressure reading from first pressure reading for one fuel injector. Result is pressure drop value. Obtain a pressure drop value for each fuel injector. Add all individual pressure drop values. This is total pressure drop. Divide total pressure drop by number of fuel injectors. This is average pressure drop. Does any fuel injector have a pressure drop value that is more than average pressure drop or less than average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOMS»(ref-152915-S31711482542003030500000) in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
7. Replace affected fuel injectors. After repairs, go to next step.
8. Operate system in order to verify repair. Does a driveability condition still exist? If yes, go to «SYMPTOMS»(ref-152915-S31711482542003030500000) in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, system is okay.

The PCM enables appropriate fuel injector on intake stroke for each cylinder. A voltage is supplied directly to fuel injectors. PCM controls each fuel injector by grounding Control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low, will affect engine driveability. A Fuel Injector Control circuit DTC may not set, but a misfire may be apparent. Fuel injector coil windings are affected by temperature. Resistance of fuel injector coil windings will increase as temperature of fuel injector increases.

Diagnostic Aids

1. Monitoring misfire current counters or misfire graph, may help isolate fuel injector that is causing condition.
2. Operating vehicle over a wide temperature range may help isolate fuel injector that is causing condition.
3. Perform fuel injector coil test within conditions of customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
4. If fuel injector coil test does not isolate condition, perform fuel injector balance test. See «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-153136-S12403684012003031900000) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-153136-S19505379522003031900000) .

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Observe Engine Coolant Temperature (ECT) parameter with scan tool. Is ECT value within 50-90°F (10-32°C)? If yes, go to next step. If no, go to step 4 .
3. Disconnect fuel injector multi-way harness connector. With DVOM, measure resistance of each fuel injector between Ignition Feed circuit and Fuel Injector Control circuit, at multi-way connector. See «WIRING DIAGRAMS»(ref-153136-S10222369522003112400000) . Do any fuel injectors display a resistance outside 11-14 ohms? If yes, go to step 5 . If no, go to «DIAGNOSTIC AIDS»(ref-153136-S40229467792003031900000) .
4. Disconnect fuel injector multi-way harness connector. With DVOM, measure resistance of each fuel injector between Ignition Feed circuit and Fuel Injector Control circuit, at multi-way connector. Record each fuel injector value. Subtract lowest resistance value from highest resistance value. Is difference 3 ohms or less? If yes, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-153136-S12403684012003031900000) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-153136-S19505379522003031900000) . If no, go to step 8 .
5. Remove upper intake manifold. After removing upper intake manifold, go to next step.
6. Using a DVOM, measure resistance of the ignition 1 voltage circuit between the multi-way connector and affected fuel injector connector. Is resistance more than 5 ohms? If yes, go to next step. If no, go to step 9 .
7. Repair open or high resistance in the ignition 1 voltage circuit. After repairs, go to step 11 .
8. Add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest and the highest individual fuel injector resistance values from the average resistance value. Replace fuel injector that displays the greatest resistance difference, above or below the average. After replacing injector(s), go to step 11 .
9. Test for an intermittent and for a poor connection at the affected fuel injector. Did you find and correct the condition? If yes, go to step 11 . If no, go to next step.
10. Replace any fuel injectors that are out of the specified range of 11-14 ohms. After replacing injector(s), go to next step.
11. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2 .

Scheme 6

When ignition is turned on, the control module enables the fuel pump relay to turn on. The fuel pump remains on as long as engine is cranking or running and control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump off within 2 seconds after ignition was turned on or if engine stops.

Listen for an audible hiss from fuel pump when fuel pump relay is commanded on. A vibration in the fuel feed line when fuel pump relay is commanded on indicates that the fuel pump is operating.

1. Perform diagnostic system check. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing diagnostic system check, go to next step.
2. Turn ignition on, with engine off. Using scan tool, command the fuel pump relay ON and OFF. Does the fuel pump turn ON and OFF? If yes, problem is intermittent. If yes, go to next step.
3. Using scan tool, command fuel pump relay ON and OFF. Do you hear a click when you command the fuel pump relay ON and OFF? If yes, go to step 9. If no, go to next step.
4. Turn ignition off. Disconnect fuel pump relay, located in underhood fuse/relay block. Turn ignition on, with engine off. Probe control circuit of the fuel pump relay with a test light that is connected to a good ground. (Scheme 6) With scan tool, command the fuel pump ON and OFF. Does the test light turn ON and OFF? If yes, go to next step. If no, go to step 6.
5. Connect the test light between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. With a scan tool, command the fuel pump ON and OFF. Does test light turn ON and OFF? If yes, go to step 21. If no, go to step 24.
6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step 8.
7. Test the control circuit of the fuel pump relay for a short to voltage. Did you find and correct the condition? If yes, go to step 29. If no, go to step 28.
8. Test control circuit of the fuel pump relay for a short to ground or an open. Did you find and correct the condition? If yes, go to step 29. If no, go to step 22.
9. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step 11.
10. Turn ignition off. Disconnect fuel pump relay, located in underhood fuse/relay block. Turn ignition on, with engine off. Does the fuel pump operate continuously? If yes, go to step 23. If no, go to step 27.
11. Is the fuel pump fuse open? If yes, go to next step. If no, go to step 14.
12. Disconnect the fuel pump harness in-line connector, located near fuel tank. Test the fuel pump supply voltage circuit for a short to ground. (Scheme 6) Replace fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step 29. If no, go to next step.
13. Lower fuel tank, if necessary. Test or inspect the fuel tank electrical harness for damage or grounded circuit. Replace the fuel pump fuse, if necessary. Did you find and correct the condition? If yes, go to step 29. If no, go to step 20.
14. Turn ignition off. Disconnect fuel pump relay. Turn ignition on, with engine off. Probe the battery positive voltage circuit of the fuel pump relay with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step 25.
15. Connect a 10-amp fused jumper wire between the battery positive voltage circuit and fuel pump supply voltage circuit in the fuel pump cavity. Does the fuel pump operate? If yes, go to step 21. If no, go to next step.
16. Disconnect the fuel pump harness in-line connector located near the fuel tank. Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the in-line connector. Did you find and correct the condition? If yes, go to step 29. If no, go to next step.
17. Test the ground circuit of the fuel pump for an open or high resistance between the body pass-through connector and the ground. Did you find and correct the condition? If yes, go to step 29. If no, go to next step.
18. Inspect for poor connections at the fuel pump in-line connector to the body pass-through connector. Did you find and correct the condition? If yes, go to step 29. If no, go to next step.
19. Lower fuel tank. Test or inspect the fuel tank electrical harness for damage or open circuit. Did you find and correct the condition? If yes, go to step 29. If no, go to step 26.
20. Connect all disconnected components. Install a new fuel pump fuse. With a scan tool, command the fuel pump ON. Is the fuel pump fuse open? If yes, go to step 26. If no, problem is intermittent.
21. Inspect for poor connections at the fuel pump relay. Did you find and correct the condition? If yes, go to step 29. If no, go to step 27.
22. Inspect for poor connections at PCM harness. Did you find and correct the condition? If yes, go to step 29. If no, go to step 28.
23. Repair fuel pump supply voltage circuit for a short to voltage. After repairs, go to step 29.
24. Repair fuel pump relay ground circuit for an open ground. After repairs, go to step 29.
25. Repair battery positive voltage circuit of the fuel pump relay for an open. After repairs, go to step 29.
26. Replace fuel pump. After replacing fuel pump, go to step 29.
27. Replace fuel pump relay. After replacing relay, go to step 29.
28. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM programing. After replacing PCM, go to next step.
29. Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 2.

FUEL SYSTEM PRESSURE TEST

Note. For fuel system pressure testing, see FUEL SYSTEM PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.4L AZTEK & RENDEZVOUS article.

1. Operate vehicle under condition of customer's concern. Under high temperature conditions fuel vapors may increase to a point of EVAP canister vapor saturation. Fuel vapors would then be released into atmosphere. Once engine is running and EVAP purge is enabled, all fuel vapor release would be eliminated.
2. Test for fuel leaking in fuel tank, rear tank if equipped, and fuel feed and return pipes.
3. Test for fuel vapor leaks in fuel tank, fill limiter vent valve and rollover valves, fuel fill pipe, hose and fuel fill cap, fuel sender housing and seal, Fuel Tank Pressure (FTP) sensor seal and EVAP vapor pipe.
4. Movement of EVAP pipes or fuel pipes may help find an intermittent condition.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article.
2. Raise vehicle. Inspect fuel tank and fuel pipes for damage or external leaks. Did you find fuel leaking from fuel tank? If yes, go to step 7 . If no, go to next step.
3. Turn ignition on, with engine off. Using scan tool, command fuel pump ON. Inspect for fuel leaking from fuel pipes. Did fuel leak from fuel pipes? If yes, go to step 8 . If no, go to next step.
4. Install Fuel Tank Cap Adapter (J-41415-40). Connect EVAP Pressure/Purge Diagnostic Station (J-41413) to fuel tank cap adapter. With scan tool, seal EVAP system. DO NOT exceed 15 in. H2O. With EVAP pressure/purge diagnostic station, pressurize fuel tank. Did fuel leak from fuel tank? If yes, go to step 7 . If no, go to next step.
5. With EVAP pressure/purge diagnostic station, maintain pressure in fuel tank. With Ultrasonic Leak Detector (J-41416), test for leaks above fuel level in following locations: Fuel tank, fill limiter vent valve, pressure relief valve and rollover valves. Fuel sender housing and fuel sender seal. Fuel Tank Pressure (FTP) sensor seal. EVAP vapor pipes. Fuel fill pipe and hose. Did you locate a fuel leak? If yes, go to next step. If no, see «DIAGNOSTIC AIDS»(ref-153136-S18485585442003031900000) .
6. Repair system as necessary. After repairs, system is okay.
7. Replace fuel tank. After repairs, system is okay.
8. Replace leaking fuel pipe. After repairs, system is okay.

Inspect for the following conditions

1. High resistance in an IAC valve control circuit.
2. The correct PCV valve, properly installed and proper operation of the PCV valve.
3. Proper operation and installation of all air intake components.
4. Proper installation and operation of the MAF sensor.
5. A tampered with or damaged throttle stop screw.
6. A tampered with or damaged throttle plate, throttle shaft, throttle linkage, or cruise control linkage, if equipped.
7. A skewed high TP sensor.
8. Excessive deposits in IAC passage or on IAC pintle.
9. Excessive deposits in the throttle bore or on the throttle plate.
10. Vacuum leaks.
11. A high or unstable idle condition could be caused by a non-IAC system problem that cannot be overcome by the IAC valve.
12. An intermittent condition.

1. Perform Diagnostic System Check - Engine Controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-155075-S24848794192003060600000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. After performing Diagnostic System Check - Engine Controls, go to next step.
2. Set parking brake and block drive wheels. Install scan tool. Start engine. Turn all accessories off. Using scan tool RPM control function, slowly increment engine speed to 1700 RPM, then to 600 RPM. Then to 1700 RPM. Exit RPM control function. Did the engine speed stabilize within 100 RPM less than the commanded engine speed or within 150 RPM above the commanded RPM? If yes, see «DIAGNOSTIC AIDS»(ref-153136-S38765131982003031900000) . If no, go to next step.
3. Turn ignition off. Disconnect IAC valve harness connector. See «WIRING DIAGRAMS»(ref-153136-S10222369522003112400000) . Connect IAC System Motor Analyzer (J-37027-A) to IAC valve. Start engine. Using IAC system motor analyzer, command IAC valve in until about 600 RPM is reached and then command IAC valve out until about 1700 RPM is reached. Return engine RPM to desired idle as indicated on scan tool data list. Did the engine speed steadily decrease to near 600 RPM and steadily increase to near 1700 RPM when the IAC valve was commanded in and out? If yes, go to step 5 . If no, go to next step.
4. Did you observe an excessively high idle condition that could not be controlled with the IAC motor driver during the last test? If yes, go to step 11 . If no, go to step 12 .
5. Using a test light connected to ground, probe one IAC valve circuit at IAC valve harness connector. See «WIRING DIAGRAMS»(ref-153136-S10222369522003112400000) . Start engine. Using IAC system motor analyzer, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine to idle as indicated on scan tool data list. Repeat procedure for other three IAC valve circuits. Did the test light remain ON, never flashing, while the IAC counts where incrementing at any of the IAC valve circuits during the above test? If yes, go to step 10 . If no, go to next step.
6. Did the test light remain OFF, never flashing, while the IAC counts where incrementing at any of the IAC valve circuits during the above test? If yes, go to step 9 . If no, go to next step.
7. Using Connector Test Adapter Kit (J-35616-A) connect a test light between IAC coil "A" low circuit and IAC coil "A" high circuit at IAC valve harness connector. Using IAC system motor driver, command low RPM while observing scan tool until IAC counts start to increment, then command high RPM until IAC counts start to increment. Observe test light while incrementing IAC counts. Return engine speed to desired idle as indicated on scan tool data list. Repeat procedure on IAC coil "B" low circuit and IAC coil "B" high circuit. Did the test light stay illuminated, never flashing, while the IAC counts where incrementing during the above test? If yes, go to next step. If no, go to step 17 .
8. Check for poor connection at IAC valve harness connector. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
9. Turn ignition off. Disconnect PCM harness connectors. With a DVOM, test the circuit where the test light remained off for the following: An open circuit. A short to ground. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
10. Turn ignition on. With a DVOM, test the circuit where the test light remained illuminated for the following: A short to voltage. A short to another IAC valve circuit. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 13 .
11. Visually and physically inspect for the following: Throttle body damage and tampering. Skewed TP sensor signal. Throttle lever screw tampering (if equipped). Vacuum leaks. Faulty, incorrectly installed PCV valve and hose (if equipped). Throttle shaft binding. Throttle linkage or cruise control linkage binding (if equipped). Remove IAC valve. Inspect for the following: Clogged IAC passage. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Excessive deposits on IAC valve pintle. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
12. Visually and physically inspect for the following: Throttle body damage and tampering. Throttle lever screw tampering (if equipped). Restricted air intake system. Excessive deposits on throttle plate. Excessive deposits in throttle bore. Remove IAC valve and inspect for excessive deposits on IAC valve pintle and in IAC valve passage. Repair as necessary. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 15 .
13. Check for poor PCM harness connections. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
14. Disconnect the PCM harness connectors. With a DVOM, test all IAC valve circuits for high resistance. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 17 .
15. Check for poor IAC valve harness connection. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
16. Replace IAC valve. After repairs, go to step 18 .
17. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedures. After repairs, go to next step.
18. Reconnect any disconnected components. Use the scan tool to clear any DTCs that may have set. Turn OFF the ignition for 30 seconds. Operate the vehicle within conditions to verify the repair. Did you verify the repair? If yes, go to next step. If no, go to step 2 .
19. With a scan tool, observe the stored information in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-155075-S27919636112003060600000) in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article. If no, system is okay.

Scheme 7

EVAP Control System Diagnosis

For EVAP control system diagnosis, see appropriate INSPECTION/MAINTENANCE PROCEDURES under DRIVE CYCLES in SELF-DIAGNOSTICS - 3.4L AZTEK & RENDEZVOUS article.