Engine Control System - System & Component Testing: Diagnosis Pontiac Vibe I

Auxiliary Intake Air Control Solenoid Inspection With Scan Tool

The auxiliary intake air control solenoid is operated by the Powertrain Control Module (PCM). PCM supplies a ground path to the solenoid control circuit using an internal solid state device called a driver. When PCM commands the solenoid ON, voltage on the control circuit should be near zero or low. When PCM commands the solenoid OFF, voltage on the control circuit should be near battery voltage or high. When the solenoid is energized, manifold vacuum is applied to the vacuum motor and the auxiliary inlet air duct door is closed.

Diagnostic Procedures

1. Turn ignition switch to OFF position. Disconnect auxiliary intake air control solenoid harness connector. Measure resistance of the solenoid using a DMM. (Scheme 60) Is the resistance 37-44 ohms at 68°F (20°C)? If yes, go to next step. If no, go to step 10.
2. Disconnect the two vacuum hoses from the intake air control solenoid. Connect Hand Vacuum Pump (J 23738-A), or equivalent, to the inboard port of the intake air control solenoid. Plug outboard port of the intake air control solenoid. Observe the vacuum pump gauge while attempting to apply 15 in. Hg of vacuum. Did the vacuum indicated by the vacuum pump remain at zero? If yes, go to next step. If no, go to step 10.
3. Connect scan tool. Connect the solenoid harness connector. Turn ignition switch to RUN position, engine OFF. Command the intake air control solenoid ON with the scan tool. See «SCAN TOOL OUTPUT CONTROLS - ENGINE CONTROLS»(ref-152429-S16892465302003031500000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article. Observe the vacuum pump gauge while attempting to apply 15 in. Hg of vacuum. Did the vacuum indicated by the vacuum pump reach 15 in. Hg? If yes, go to next step. If no, go to step 5.
4. Command the intake air control solenoid OFF using the scan tool. Did vacuum indicated by the vacuum pump drop to zero? If yes, system is okay at this time. If no, go to step 9.
5. Disconnect the auxiliary intake air control solenoid harness connector. Turn ignition switch to RUN position, engine OFF. Using a test light connected to ground, probe the ignition positive voltage circuit at the solenoid harness connector. Does the test light illuminate? If yes, go to next step. If no, go to step 8.
6. Connect test light across the terminals of the solenoid harness connector. Using the scan tool, command the solenoid ON. Does the test light illuminate? If yes, go to step 10. If no, go to next step.
7. Test for an open or a short to voltage in the solenoid control circuit. Repair as necessary. Did you find and correct a condition? If yes, go to step 3.
8. Repair the open in the ignition positive voltage circuit. After repair, go to step 3.
9. Test for a short to ground in the solenoid control circuit. Repair as necessary. Did you find and correct a condition? If yes, go to step 3. If no, go to step 11.
10. Replace the auxiliary intake air control solenoid. See «AUXILIARY INTAKE AIR CONTROL SOLENOID»(ref-153233-S26812230032003032600000) under MOTORS, RELAYS & SOLENOIDS in REMOVAL & INSTALLATION - VIBE article. After repair, go to step 2.
11. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to step 3.

Auxiliary Intake Air Control Solenoid Inspection W/O Scan Tool

The auxiliary intake air control solenoid is operated by the Powertrain Control Module (PCM). The PCM supplies a ground path to the solenoid control circuit using an internal solid state device called a driver. When the PCM commands the solenoid ON, voltage on the control circuit should be near zero or low. When PCM commands the solenoid OFF, voltage on the control circuit should be near battery voltage or high. When the solenoid is energized, manifold vacuum is applied to the vacuum motor and the auxiliary inlet air duct door is closed.

1. Disconnect the intake air control solenoid harness connector.
2. Using DMM, measure the solenoid resistance value. (Scheme 60) Resistance should be 37-44 ohms at 68°F (20°C).
3. Replace the solenoid if the resistance is not as specified.
4. Using DMM, check for continuity between each solenoid terminal and the solenoid housing. (Scheme 61) The DMM should read infinite (OL).
5. Replace the intake air control solenoid if the resistance is not within specification. A shorted solenoid may cause damage to the PCM.
6. Blow air through the inboard port of the intake air control solenoid. (Scheme 62) Air has to flow freely through the vent port and NOT out of the outboard port.
7. Replace the solenoid if air flows from the inboard port out through the outboard port or air does not flow from the inboard port out through the vent port.
8. Apply battery voltage across the solenoid terminals. (Scheme 63)
9. Blow air through the inboard port of the solenoid. Air should flow through the solenoid and out of the outboard port. (Scheme 63)
10. Replace the solenoid if the solenoid fails any of the tests.
11. Connect the harness connector of the intake air control solenoid.
12. Start the engine.
13. Verify the intake air control solenoid is ON.
14. If the solenoid is not energized, disconnect the solenoid harness connector and connect a test light across the terminals of the solenoid circuit.
15. If the test light illuminated, replace the solenoid.
16. If the test light did not illuminate, check for an open in the ignition positive voltage supply to the solenoid, or an open or a short to voltage in the solenoid control circuit.
17. Repair any electrical circuit conditions as necessary.
18. If you did not find and repair an electrical condition, replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article.

Scheme 60

Scheme 61

Scheme 62

Scheme 63

Vacuum Check Valve Inspection

Note. Numbers in parenthesis in the test steps correspond to those in figure. (Scheme 64)

1. Remove the vacuum check valve (1) from the auxiliary intake air system. (Scheme 64)
2. Connect Hand Vacuum Pump (J 23738-A), or equivalent, to the intake manifold side of the vacuum check valve. (Scheme 65)
3. Attempt to apply a vacuum of 10 in. Hg to the vacuum check valve.
4. The check valve should NOT hold vacuum pressure.
5. Disconnect the vacuum pump from the check valve.
6. Connect the hand vacuum pump to the other side of the check valve.
7. Apply a vacuum of 10 in. Hg to the vacuum check valve.
8. The check valve SHOULD hold vacuum pressure.
9. Replace the vacuum check valve if the valve failed either of the previous tests.
10. Install the vacuum check valve (1).
11. Ensure check valve (1) is installed with the side that holds vacuum toward the intake air control solenoid (4). (Scheme 64)

Scheme 64

Scheme 65

Auxiliary Intake Air Door Inspection

1. To view the operation of the auxiliary intake air door, remove the air cleaner cover and air cleaner element.
2. Verify auxiliary intake air door is OPEN.
3. If the intake air door is closed test for a faulty intake air control solenoid.
4. Disconnect the vacuum hose to the auxiliary intake air door motor.
5. Check if auxiliary intake air door is OPEN.
6. Replace the air cleaner assembly if the intake air door is closed.
7. Connect the Hand Vacuum Pump (J 23738-A), or equivalent, to the intake air door motor.
8. Apply a vacuum of 10 in. Hg to the intake air door motor.
9. The intake air door motor should CLOSE and HOLD vacuum.
10. Replace the air cleaner assembly if the intake air door fails the previous test.
11. Connect the hand vacuum pump to the vacuum storage chamber on the air cleaner upper assembly.
12. Apply a vacuum of 10 in. Hg to the storage chamber.
13. The vacuum chamber should HOLD the vacuum pressure.
14. Replace the air cleaner assembly if the vacuum storage chamber looses pressure.

Circuit Description

The EFI relay provides ignition positive voltage to the control module and other engine control components anytime the ignition switch is in RUN position. One side of the coil of the EFI relay is always grounded. The other side of the coil receives 12 volts from the Powertrain Control Module (PCM). When the coil is energized, a magnetic field closes the switch side of the relay, supplying power to the following engine components

1. The fuel pump relay, also called the circuit opening relay.
2. The Heated Oxygen Sensors (HO2S).
3. The Mass Air Flow (MAF) sensor.
4. The Evaporative Emission (EVAP) control system solenoids.
5. The Idle Air Control (IAC) valve.
6. PCM.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Test for an open EFI fuse. Was an open fuse found? If yes, go to step 10. If no, go to next step.
3. Turn ignition switch to RUN position, engine OFF. Remove and reinstall the EFI relay several times while listening for a clicking sound from the relay. Did the EFI relay click when being reinstalled into the fuse block? If yes, go to next step. If no, go to step 5.
4. Turn ignition switch to OFF position. Remove EFI relay from the underhood fuse block. Turn ignition switch to RUN position, engine OFF. Probe the fuse block side of terminal No. 5 using a test light connected to ground. (Scheme 66) Does the test light illuminate? If yes, go to step 11. If no, go to step 7.
5. Probe EFI relay terminal No. 1 on the fuse block side using a test light connected to ground. (Scheme 66) Does the test light illuminate? If yes, go to next step. If no, go to step 8.
6. Turn ignition switch to OFF position. Probe EFI relay terminal No. 2 of on the fuse block side using a test light connected to battery voltage. Does the test light illuminate? If yes, go to step 12. If no, go to step 9.
7. Repair the open or poor connection in the ignition positive voltage circuit between the EFI fuse and the EFI relay. After repair, go to step 14.
8. Check for an open, a poor connection, or a short to ground in the EFI relay control circuit between the EFI relay and the PCM. Repair as necessary. Did you find and correct the condition? If yes, go to step 14. If no, go to step 13.
9. Repair the open in the ground circuit between the EFI relay and ground point G103. After repair, go to step 14.
10. Repair the short to ground in the EFI fuse circuit. After repair, go to step 14.
11. Check EFI relay circuit for an open or a poor connection, from terminal No. 3 to the component or system that is not receiving voltage. Repair as necessary. Did you find and correct a wiring fault? If yes, go to step 14. If no, go to next step.
12. Replace the EFI relay. After repair, go to step 14.
13. Replace PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to next step.
14. Operate the vehicle within the conditions under which the original concern was noted. Does the system operate properly with no DTCs? If yes, system is okay at this time. If no, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-152429-S35671638322003020400000) in SELF-DIAGNOSTICS - VIBE article.

Diagnostic Aids

Check for any of the following conditions

1. Check the resistance of the EFI relay. There is continuity across terminals No. 1 and 2. The resistance across terminals No. 5 and 3 is infinite.
2. The EFI relay electrical contacts may be pitted or sticking. Replace the EFI relay if tapping gently on the relay or wiggling the relay causes a change in the relay's operation.
3. The performance of the EFI relay may be affected by temperature. Check the EFI relay after sitting outside overnight and after running the engine 30 minutes.
4. If the EFI fuse opens during cranking, check for a shorted fuel pump/circuit. The EFI relay supplies current to the circuit opening relay that supplies power the fuel pump. The circuit opening relay is energized during cranking and when reference pulses are detected by the PCM.

An intermittent malfunction may be caused by a fault in the EFI relay electrical circuit. Inspect the wiring harness and components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. For terminal identification (Scheme 66)

Scheme 66

The circuit opening relay provides ignition positive voltage to the fuel pump. The circuit opening relay is controlled by the Powertrain Control Module (PCM) and receives ignition positive voltage from the EFI relay. PCM monitors the crank signal circuit for voltage when the ignition switch is in the START (engine cranking) position. When the crank signal circuit indicates the engine is cranking the PCM energizes the circuit opening relay. PCM also energizes the circuit opening relay whenever reference pulses from the Crankcase Position (CKP) sensor circuit are detected. If the crank signal circuit does NOT indicate the engine is cranking the PCM will energize the circuit opening relay based only upon reference pulses.

Diagnostic Procedure

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Connect scan tool. Remove the bottom cushion of rear seat to gain access to the fuel sender assembly access panel. Place a listening device against the fuel sender assembly access panel. Turn ignition switch to RUN position, engine OFF. Command the fuel pump ON and OFF using the scan tool. Listen for audible fuel pump operation. Does the fuel pump operate as commanded? If yes, go to next step. If no, go to step 4.
3. The fuel pump electrical circuit is OK. Do you want to inspect the fuel system for the correct operating pressure? If yes, go to «FUEL SYSTEM DIAGNOSIS»(ref-152779-S03797432242003031100000)
4. Is the fuel pump operating continuously when the ignition is in RUN position with engine OFF? If yes, go to step 15. If no, go to next step.
5. Turn the fuel pump ON and OFF while listening carefully for the operation of the circuit opening relay near the instrument panel fuse block. Did you hear the circuit opening relay click when commanded ON and OFF using the scan tool? If yes, go to step 10. If no, go to next step.
6. Turn ignition switch to OFF position. Remove the circuit opening relay. Turn ignition switch to RUN position, engine OFF. Probe the circuit opening relay cavity No. 1 and cavity No. 2 using a test light connected to ground. (Scheme 66) Did the test light illuminate at both cavities? If yes, go to next step. If no, go to step 9.
7. Using a test light connected to battery voltage, probe the circuit opening relay control circuit cavity No. 3. Command the fuel pump ON using the scan tool. Does the test light illuminate? If yes, go to step 19. If no, go to next step.
8. Check for an open in the circuit opening relay control circuit. Repair as necessary. Was a wiring fault found and repaired? If yes, go to step 22. If no, go to step 21.
9. Check for the cause of no ignition positive voltage to the circuit opening relay. Repair as necessary. After repair, go to step 22.
10. Remove the fuel sender assembly access panel. Disconnect fuel sender assembly harness connector. Probe the fuel pump ignition positive voltage circuit, terminal No. 4, using a test light connected to ground. Command the fuel pump ON using the scan tool. Does the test light illuminate? If yes, go to next step. If no, go to step 13.
11. Connect the test light between the fuel pump ground circuit and battery voltage. Does the test light illuminate? If yes, go to step 14. If no, go to next step.
12. Repair the open fuel pump ground circuit. After repair, go to step 22.
13. Repair open fuel pump power circuit between the circuit opening relay and fuel sender assembly. After repair, go to step 22.
14. Inspect the fuel sender assembly for an open or high resistance in the fuel pump positive voltage circuit and the fuel pump ground circuit. Repair or replace the fuel sender assembly as necessary. Was a repair or replacement necessary? If yes, go to step 22. If no, go to step 20.
15. Remove the circuit opening relay. Is the fuel pump still operating? If yes, go to next step. If no, go to step 17.
16. Repair the short to voltage in the fuel pump supply circuit. After repair, go to step 22.
17. Turn ignition switch to OFF position. Probe the control circuit, relay socket cavity No. 3, using a test light connected to battery voltage. (Scheme 66) Command the circuit opening relay ON and OFF with the scan tool. Did the test light stay illuminated even when the relay was commanded OFF? If yes, go to next step. If no, go to step 19.
18. Inspect for a short to ground in the circuit opening relay control circuit between the relay and PCM. Repair the wiring as necessary. Did you find and repair a wiring short? If yes, go to step 22. If no, go to step 21.
19. Replace the circuit opening relay. After repair, go to step 22.
20. Replace the fuel pump. See «FUEL PUMP»(ref-153233-S23248500372003032600000) under FUEL SYSTEMS in REMOVAL & INSTALLATION - 1.8L VIBE article. After repair, go to step 22.
21. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - 1.8L VIBE article. After repair, go to step 22.
22. Operate vehicle within the conditions under which the original symptom was noted. Does the system operate correctly now? If yes, system is okay at this time. If no, go to «DIAGNOSTIC AIDS»(ref-152779-S31253650712003031900000).

Check for any of the following conditions

1. The resistance of the circuit opening relay, the resistance across terminals No. 2 and 3 is 85-95 ohms at 68°F (20°C). The resistance across terminals No. 1 and 4 is infinite.
2. The circuit opening relays electrical contacts may be pitted or sticking. Replace the relay if tapping gently on the relay or wiggling the relay causes a change in the relays operation.
3. The performance of the circuit opening relay may be affected by temperature. Check the relay after sitting outside overnight and after running the engine 30 minutes.

An intermittent malfunction may be caused by a fault in the fuel pump electrical circuit. See

INTERMITTENTS

in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. See

(Scheme 66)

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Turn ignition switch to OFF position. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-152779-S28904540322003022500000) procedure. Install a fuel pressure gauge. See «FUEL GAUGE»(ref-153233-S05610451762003032700000) under FUEL SYSTEMS in REMOVAL & INSTALLATION - 1.8L VIBE article. Connect scan tool. Turn ignition switch to RUN position, engine OFF. Select FUEL PUMP in ENGINE OUTPUT CONTROLS menu of the scan tool. Using the scan tool, turn the fuel pump ON. Observe the fuel pressure indicated by the fuel pressure gauge with the fuel pump running. Is any fuel pressure indicated? If yes, go to next step. If no, go to step 5 .
3. Using the scan tool, turn the fuel pump ON. Observe fuel pressure indicated by the fuel pressure gauge with the fuel pump running. Is fuel pressure 44-50 psi (301-347 kPa)? If yes, go to step 12 . If no, go to next step.
4. Is the fuel pressure more than 50 psi (347 kPa)? If yes, go to step 22 . If no, go to next step.
5. Was the circuit opening relay diagnostic performed? If yes, go to step 24 . If no, go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(ref-152779-S09783568912003031800000) .
6. Remove the bottom cushion of the rear seat to gain access to the fuel sender assembly access panel. Turn ignition switch to RUN position, engine OFF. Place a listening device against the access panel. Command the fuel pump ON, using the scan tool. Listen for audible fuel pump operation. The fuel pump should have a smooth and steady low humming sound. Is the fuel pump operating as described? If yes, go to next step. If no, go to step 24 .
7. Measure the resistance of the fuel pump, with a DMM. Is the fuel pump resistance 0.2-3.0 ohms at 68°F (20°C)? If yes, go to next step. If no, go to step 24 .
8. Visually and physically check the fuel feed pipe for kinks, cracks, incorrect routing or restrictions. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no, go to next step.
9. Remove the fuel sender assembly. Visually and physically check the fuel pump strainer for plugging or restriction. Was the fuel pump strainer found to be plugged? If yes, go to step 23 . If no, go to next step.
10. Visually and physically inspect the seals and the "O" rings between the fuel pump, the fuel filter, and the fuel pressure regulator for cracks, splits, deformation or missing components. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no, go to next step.
11. Check the fuel filter for a restriction. Replace the fuel filter, if necessary. Was the fuel filter replaced? If yes, go to step 25 . If no, go to step 22 .
12. Using the scan tool, turn the fuel pump ON. Wait for the fuel pressure to stabilize. Turn the fuel pump OFF. Monitor the fuel pressure on the fuel gauge. Does the fuel pressure remain equal to or more than 21 psi (147 kPa) for 5 minutes after the fuel pump is turned OFF? If yes, go to next step. If no, go to step 17 .
13. Does the fuel pressure decrease during acceleration, cruise, or hard cornering? If yes, go to next step. If no, go to «INTERMITTENTS»(ref-153013-S39990244982003031100000) in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
14. Visually and physically inspect the fuel filter and fuel feed pipe for restrictions. Was a restriction found? If yes, go to next step. If no, go to step 16 .
15. Repair the restriction as necessary. After repair, go to step 25 .
16. Visually and physically inspect for any of the following conditions: A restricted fuel pump strainer. An incorrectly positioned fuel pump pick-up. The incorrect fuel pump. A loose or missing fuel pump or tank baffle. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no, go to step 24 .
17. Turn the fuel pump ON using the scan tool. Pinch off the fuel pressure gauge adapter hose on the fuel tank side, while monitoring the fuel gauge. Turn the fuel pump OFF. Does the fuel pressure remain equal to or more than 21 psi (147 kPa) for 5 minutes after the fuel pump is turned OFF? If yes, go to step 19 . If no, go to next step.
18. Check for a fuel leak at the base of the fuel injectors, at the fuel injectors and at the fuel rail. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no, go to step 20 .
19. Check the fuel feed pipe for leaks. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no go to next step.
20. Remove the fuel sender assembly. Visually and physically check the seals and "O" rings between the fuel pump, the fuel filter, and the fuel pressure regulator for the following conditions: Any cracks. Any splits. Any deformation. Any missing components. Inspect the entire fuel pump electrical circuit. Verify battery voltage at the fuel pump connector and less than 5.0 ohms to ground. Repair as necessary. Was a repair necessary? If yes, go to step 25 . If no, go to next step.
21. Check the fuel filter and the fuel pump for cracks or a leaking seam. Replace as necessary. Was a component replacement necessary? If yes, go to step 25 . If no, go to next step.
22. Replace the fuel pressure regulator. See «FUEL PRESSURE REGULATOR»(ref-153233-S16337396582003032600000) under FUEL SYSTEMS in REMOVAL & INSTALLATION - VIBE article. Attempt to start and run the engine. Monitor the fuel pressure gauge while the engine is running. Is the fuel pressure 44-50 psi (301-347 kPa)? If yes, go to step 25 . If no, go to next step.
23. Replace the fuel pump strainer. Inspect the fuel system for the cause of the plugged fuel pump strainer. Repair as necessary. After repair, go to next step.
24. Replace the fuel pump. See «FUEL PUMP»(ref-153233-S23248500372003032600000) under FUEL SYSTEMS in REMOVAL & INSTALLATION - VIBE article. After repair, go to next step.
25. Attempt to start and run the engine. Monitor the fuel pressure gauge while the engine is running. Is the fuel pressure 44-50 psi (301-347 kPa)? If yes, system is okay at this time. If no, go to step 2 .

ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS

The concentration of alcohol-in-fuel can be detrimental to the fuel system. Higher than recommended alcohol-in-fuel concentrations may cause driveability problems such as hesitation, lack of power, stall, no start, etc. High concentrations may also cause corrosion of the fuel system components and subsequent fuel filter plugging as well as deterioration of the rubber and the plastic components. Commercial automotive fuel can contain alcohol in various types and levels of concentration. Some forms of alcohol are more detrimental to the fuel system components than others. If an excessive amount of alcohol-in-fuel is suspected as the cause of a driveability problem, the following procedure can be used to detect its presence. This procedure uses water to extract the alcohol from the fuel. The specific type of alcohol contamination cannot be determined from this test.

Testing Procedure

The fuel sample should be drawn from the bottom of the fuel tank, because any water present in the tank will be concentrated there. The fuel sample should be bright and clear. If the sample appears to be cloudy or contaminated with the water as indicated by a water layer at the bottom of the sample, this procedure should not be used. The fuel system should be cleaned.

1. Using a 100 ml cylinder with 1 ml graduation marks, fill with the fuel sample to the 90 ml mark.
2. Add 10 ml of the water to bring the total fluid volume to 100 ml and install a stopper.
3. Shake vigorously for 10-15 seconds. Carefully loosen the stopper to release the pressure.
4. Close the stopper and shake the cylinder vigorously again for 10-15 seconds.
5. Put the graduated cylinder on a level surface for approximately 5 minutes to allow adequate time for the liquid to separate.

If there is alcohol present in the fuel, the volume of the lower layer, which will now contain both alcohol and water, will be more than 10 ml. For example, if the volume of the lower layer is increased to 15 ml, this will indicate that there is at least 5 percent alcohol in the fuel. The actual amount of the alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

The Sequential Multiport Fuel Injection (SFI) system is controlled by the Powertrain Control Module (PCM). PCM energizes the solenoid coil of each fuel injector individually by completing the electrical circuit to ground. When energized the fuel injector solenoid operates the solenoid plunger, allowing pressurized fuel to be injected into the intake port of the cylinder. The fuel pump will pressurize the fuel rail and the fuel injectors as long as the engine is cranking and the PCM is receiving the ignition system reference pulses.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Turn ignition switch to OFF position. Disconnect all 4 fuel injector harness connectors. Install a fuel injector test light into each fuel injector harness connector. Observe the injector test light for each injector while cranking the engine. Does the injector test light flash for each injector circuit while cranking the engine? If yes, go to «FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C)»(ref-152779-S06830036892003022500000) . If no, go to next step.
3. Did the fuel injector test light flash for at least one fuel injector circuit while cranking the engine? If yes, go to step 5 . If no, go to next step.
4. Check for an open in the fuel injector power circuit between the ignition switch and splice S114 and/or an open in the PCM ground circuits. Repair as necessary. After repair, go to step 12 .
5. Was the injector test light illuminated steady for any fuel injector circuit? If yes, go to next step. If no, go to step 8 .
6. Turn ignition switch to OFF position. Install the fuel injector test lead in any fuel injector circuit that stays ON. Disconnect PCM 34-pin harness connector C1. Turn ignition switch to RUN position, engine OFF. Does the fuel injector test light illuminate? If yes, go to next step. If no, go to step 11 .
7. Repair the short to ground in the faulty fuel injector control circuit between the PCM and the fuel injector. After repair, go to step 12 .
8. Remove the injector test light from the fuel injector harness connector. Connect a test light from ground to the ignition positive voltage side of the fuel injector harness connector that did not flash. Turn ignition switch to RUN position, engine OFF. Does the test light illuminate? If yes, go to step 10 . If no, go to next step.
9. Repair the open in the ignition feed circuit between the fuel injector and splice S114. After repair, go to step 12 .
10. Check for an open in the faulty fuel injector control circuit. Repair as necessary. Repeat steps 5 - 10 until the injector test light flashes in all 4 fuel injector circuits. Was a repair necessary? If yes, go to step 12 . If no, go to next step.
11. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to next step.
12. Use scan tool to clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate vehicle within the conditions that caused the concern. Does the fuel system now operate properly? If yes, go to next step. If no, go to «DIAGNOSTIC AIDS»(ref-152779-S24161704072003031900000) .
13. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-152429-S35671638322003020400000) in SELF-DIAGNOSTICS - 1.8L VIBE article. If no, system is okay at this time.

Check for any of the following conditions

1. Water, contaminated fuel, or inferior quality fuel can cause a no start or hard start condition even though the fuel injectors and circuitry are okay.
2. Check for a faulty spray pattern from the fuel injector nozzle if both the fuel injector solenoid and the fuel injector circuit are okay.
3. There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If the fuel injectors and the injectors' circuit are okay, and fuel spray is detected, some fuel injector nozzles may be partly blocked or restricted. If PCM receives incorrect inputs from the various information sensors, the fuel delivered by the fuel injectors may be inadequate to start the engine. Check all engine data parameters with a scan tool and compare the values indicated with expected values or values on a known good vehicle.
4. The normal fuel injector resistance is 13.4-14.4 ohms at 68°F (20°C).
5. If you were sent here by DTC P0300 and all the injectors checked okay, the MISFIRE CURRENT CYLINDER or MISFIRE GRAPHIC information on a scan tool can be used to determine which injector circuit should be examined more closely.

An intermittent malfunction may be caused by a fault in the fuel injector electrical circuit. Inspect the wiring harness and the components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Connect scan tool. Check engine coolant temperature. Is the engine coolant temperature 50-95°F (10-35°C)? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE OUTSIDE 50-95°F (10-35°C)»(ref-152779-S00127225072003031100000).
3. Turn ignition switch to OFF position. Relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-152779-S28904540322003022500000). Connect the Fuel Injector Tester (J 39021), or equivalent, to battery voltage and ground. Set the amperage supply selector switch on the fuel injector tester to the COIL TEST 0.5 AMP position. Connect leads from a DMM to the fuel injector tester. see scheme 27 Set DMM to the tenths scale (0.0). Disconnect fuel injector harness connector. Using 2 jumper wires from the Connector Test Adapter Kit (J 35616-A), or equivalent, connect the fuel injector to the J 39021 tester leads. Check the engine coolant temperature again to ensure that the correct chart is being used. Press the PUSH TO START TEST button on the fuel injector tester. Observe the voltage reading on the DMM. The voltage reading may rise during the test. Record the lowest voltage observed after the first second of the test. Repeat procedure for each fuel injector. Did any fuel injector have an erratic voltage reading or a voltage reading outside of 6.7-7.7 volts? If yes, go to next step. If no, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-152779-S08897027942003022500000).
4. Replace the faulty fuel injectors. After repair, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-152779-S08897027942003022500000).

FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE OUTSIDE 50-95°F (10-35°C)

The numbers below refer to the step numbers on the diagnostic procedures.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Connect scan tool. Check engine coolant temperature. Is the engine coolant temperature outside 50-95°F (10-35°C)? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C)»(ref-152779-S06830036892003022500000).
3. Turn ignition switch to OFF position. To prevent flooding of a single cylinder and possible engine damage, relieve fuel pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-152779-S28904540322003022500000). Connect the Fuel Injector Tester (J 39021), or equivalent, to battery voltage and ground. Set the amperage supply selector switch on the fuel injector tester to the COIL TEST 0.5 AMP position. Connect leads from a DMM to the fuel injector tester. see scheme 27 Set DMM to the tenths scale (0.0). Disconnect fuel injector harness connector. Use 2 jumper wires from the Connector Test Adapter Kit (J 35616-A), or equivalent, connect the fuel injector to the J 39021 tester leads. Check the engine coolant temperature again to ensure that the correct chart is being used. Press the PUSH TO START TEST button on the fuel injector tester. Observe the voltage reading on the DMM. The voltage reading may rise during the test. Record the lowest voltage observed after the first second of the test. Repeat procedure for each fuel injector. Identify the highest voltage reading recorded other than those more than 9.5 volts. Subtract any other voltage reading recorded from the highest voltage reading recorded. Repeat for all remaining injectors. Is any value that resulted from the subtraction more than one volt? If yes, go to next step. If no, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-152779-S08897027942003022500000).
4. Replace any fuel injector that had a subtracted value exceeding 0.6 volt, an initial reading of more than 9.5 volts or an erratic reading. After repair, go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(ref-152779-S08897027942003022500000).

Injector Balance Test Example (Typical)

For injector balance test results example, see INJECTOR BALANCE TEST EXAMPLE table and (Scheme 67).

INJECTOR BALANCE TEST EXAMPLE

Scheme 67

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Was the Fuel Injector Coil Test Procedure performed? If yes, go to next step. If no, go to «FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C)»(ref-152779-S06830036892003022500000) .
3. Is the engine coolant temperature more than 201°F (94°C)? If yes, go to next step. If no, go to step 5 .
4. Allow the engine to cool to less than the specified value. Is the engine coolant temperature less than 201°F (94°C)? If yes, go to next step.
5. Install a fuel pressure gauge. See «FUEL GAUGE»(ref-153233-S05610451762003032700000) under FUEL SYSTEMS in REMOVAL & INSTALLATION - VIBE article. Energize the fuel pump using the scan tool. Place the bleed hose of the fuel pressure gauge into an approved gasoline container. Bleed the air out of the fuel pressure gauge. Observe the reading on fuel pressure gauge. Is the fuel pressure 44-50 psi (301-347 kPa)? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(ref-152779-S03797432242003031100000) .
6. Turn the fuel pump OFF. Does the fuel pressure remain constant? If yes, go to next step. If no, go to «FUEL SYSTEM DIAGNOSIS»(ref-152779-S03797432242003031100000) .
7. Use 2 jumper wires from the Connector Test Adapter Kit (J 35616-A), or equivalent, to connect the fuel injector to the Fuel Injector Tester test leads (J 39021). Connect test leads to battery voltage and ground. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position. Energize fuel pump using the scan tool. Record fuel pressure indicated by the fuel pressure gauge after the fuel pressure stabilizes. This is the 1st pressure reading. Energize the fuel injector by depressing the PUSH TO START TEST button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gauge after the fuel pressure gauge needle has stopped moving. This is the 2nd pressure reading. Repeat procedure for each fuel injector. Subtract the 2nd pressure reading from the 1st pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Does any fuel injector have a pressure drop value that is higher or lower than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOMS - ENGINE CONTROLS»(ref-153013-S31152167912003031100000) under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
8. Re-test any fuel injector that does not meet 1.5 psi (10 kPa). Refer to the procedure in step 7) . Does any fuel injector still have a pressure drop value that is either higher or lower than the average pressure drop by 1.5 psi (10 kPa)? If yes, go to next step. If no, go to «SYMPTOMS - ENGINE CONTROLS»(ref-153013-S31152167912003031100000) under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
9. Replace the fuel injector(s). After repair, go to next step.
10. Does an engine performance concern still exist? If yes, go to «SYMPTOMS - ENGINE CONTROLS»(ref-153013-S31152167912003031100000) under SYMPTOMS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. If no, system is okay at this time.

FUEL TANK LEAK TEST

1. Drain the fuel tank.
2. Remove the fuel tank.
3. Plug the fuel feed hose, the fuel limiter vent valve hose, and the fuel tank vent valve hose on the fuel tank.
4. Plug the fuel filler neck opening.
5. Connect a piece of the hose to the breather hose nipple on the fuel tank and secure the hose with one clamp.
6. Submerge the fuel tank in water or apply a soapy solution to the outside of the tank.
7. Apply 7-15 kPa (1-2 psi) air pressure to the breather hose.
8. Air bubbles appearing from the fuel tank indicate a leak.
9. Replace the fuel tank if the tank is leaking.

The Powertrain Control Module (PCM) controls the Idle Air Control (IAC) valve to regulate air flow through the idle air bypass passage. The amount of air flowing through the idle air bypass passage determines idle speed. PCM directs IAC valve according to changes in engine load. A stalling or poor idle concern could be caused by an IAC valve that is not operating properly.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Is there a DTC P0505 set? If yes, go to «DTC P0505: IDLE CONTROL SYSTEM»(ref-152429-S07525211862003020400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 1.8L VIBE article. If no, go to next step.
3. Start engine. Run engine until a normal operating temperature of at least 174°F (80°C) is achieved. Allow engine to idle for at least 15 minutes after reaching operating temperatures. Operate engine at 2500 RPM for 90 seconds. Release throttle and wait 30 seconds while engine idle stabilizes. Observe ENGINE SPEED and IAC MOTOR COMMAND parameters on the scan tool with transmission in Park or Neutral. Are ENGINE SPEED and IAC MOTOR COMMAND within 750-850 RPM (M/T) or 700-800 RPM (A/T) 27-47% IAC Motor Command? If yes, go to step 5 . If no, go to next step.
4. Operate engine at a normal operating temperature. Select RPM CONTROL, under IAC SYSTEM, in the SPECIAL FUNCTIONS menu of the scan tool. Command IAC valve to increase and decrease engine speed using the scan tool. Did engine speed increase and decrease as commanded by the scan tool? If yes, go to next step. If no, go to step 8 .
5. Start the engine. Place transmission in Park or Neutral. Operate the following accessories, one at a time, while observing Engine Speed and IAC Motor Command parameters on the scan tool: Turn ON the headlights. Turn ON the rear window defogger, if equipped. Did IAC Motor Command increase 1-3%? If yes, go to next step. If no, go to «ELECTRICAL/ACCESSORY LOAD IDLE-UP SIGNAL DIAGNOSIS»(ref-152779-S14872662232003031200000) .
6. Turn the HVAC blower motor and the air conditioning ON, if equipped. Did the IAC Motor Command increase 4-14%? If yes, go to next step. If no, go to «ELECTRICAL/ACCESSORY LOAD IDLE-UP SIGNAL DIAGNOSIS»(ref-152779-S14872662232003031200000) .
7. Turn OFF all accessories. Turn steering wheel fully to the right and fully to the left. Return steering wheel to center, straight ahead position. Did IAC Motor Command increase 2-10%, when the steering wheel was turned all the way in either direction? If yes, go to step 16 . If no, go to «ELECTRICAL/ACCESSORY LOAD IDLE-UP SIGNAL DIAGNOSIS»(ref-152779-S14872662232003031200000) .
8. Turn ignition switch to OFF position. Disconnect IAC valve harness connector. Turn ignition switch to RUN position, engine OFF. Using a test light connected to ground, probe IAC valve harness connector terminal No. 2. Does the test light illuminate? If yes, go to next step. If no, go to step 12 .
9. Using a test light connected to battery voltage, probe IAC valve harness connector terminal No. 3. Does the test light illuminate? If yes, go to next step. If no, go to step 13 .
10. Turn ignition switch to OFF position. Using a fused jumper wire, jump IAC valve harness connector terminal No. 2 to terminal No. 2 of the IAC valve. Using a second fused jumper wire, jump IAC valve connector terminal No. 3 to terminal No. 3 of the IAC valve. Connect a fused jumper wire to IAC valve terminal No. 1. Insulate the terminal No. 1 jumper from contact to ground. Start and idle engine. With engine idling, repeatedly touch terminal No. 1 jumper to battery ground with a rapid ON-OFF motion. Does engine speed increase as the terminal No. 1 jumper is rapidly grounded ON and OFF? If yes, go to next step. If no, go to step 14 .
11. Turn ignition switch to OFF position. Remove all jumpers. Disconnect PCM harness 34-pin harness connector (containing the IAC valve open control circuit). Check terminal No. 1 of the IAC valve open control circuit for a grounded, open, or shorted to voltage circuit. Repair circuit as necessary. Was a circuit repair made? If yes, go to step 17 . If no, go to step 15 .
12. Locate the cause of no power to the IAC valve connector. See «TEST DESCRIPTION»(ref-152779-S34750983992003031500000) . Repair as necessary. After repair, go to step 17 .
13. Repair the open IAC valve ground circuit. After repair, go to step 17 .
14. Replace the IAC valve. After repair, go to step 17 .
15. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to step 17 .
16. Turn OFF all accessories. Ensure engine is operating at a normal temperature. Observe ENGINE SPEED and the IAC MOTOR COMMAND parameters on the scan tool with the transmission in Park or Neutral. Are ENGINE SPEED and IAC MOTOR COMMAND within 750-850 RPM (M/T) or 700-800 RPM (A/T), 27-47% IAC Motor Command? If yes, system is okay at this time. If no, go to «ROUGH, UNSTABLE, OR INCORRECT IDLE AND STALLING»(ref-153013-S30729456532003031100000) under SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
17. Use scan tool to clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate vehicle within the Conditions for Running the DTC as specified in the supporting text. Are any DTCs displayed on the scan tool? If yes, go to next step. If no, system is okay at this time.
18. Operate vehicle within the conditions in which the customer concern was first noticed. Is the concern still present? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-152429-S35671638322003020400000) in SELF-DIAGNOSTICS - 1.8L VIBE article.

Any condition that can affect engine performance at idle, can affect performance of the IAC system. A careful visual and/or physical inspection of the engine is necessary when the scan tool indicates engine speed or IAC Motor Command readings are out of range. An intermittent IAC system concern may be caused by poor electrical connections in the IAC valve circuits. Thoroughly check any circuitry that is suspected of causing an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.

The Powertrain Control Module (PCM) receives an idle-up signal when certain engine electrical loads or engine accessory loads are present. The PCM increases the flow of air through the idle (bypass) air passage of the Idle Air Control (IAC) valve when receiving an idle-up signal. The additional air flowing through the idle air passage causes an increase in the idle speed. The idle speed is increased to accommodate the increased engine electrical or engine accessory load. The PCM monitors the following systems for idle-up signals

1. The electric rear window defogger.
2. The exterior lighting system.
3. The A/C system. When A/C is selected from the HVAC control unit, the PCM receives a 12 volt signal. Once the PCM is aware of the request for A/C, the PCM determines whether engagement of the A/C compressor clutch is OK. To enable compressor clutch engagement the PCM provides a ground for the control circuit of the A/C compressor clutch relay. The PCM also increases engine idle speed to prevent a rough idle or a stalling condition when the A/C compressor is engaged.
4. The power steering system. The Power Steering Pressure (PSP) switch is normally open to ground. Turning the steering wheel increases the power steering oil pressure. Increased power steering oil pressure puts an additional load on the engine that may be noticeable at idle. The PSP switch closes when the power steering system oil pressure is high enough to cause an undesirable idle condition. The voltage signal from the PSP switch to the PCM indicates less than one volt when the PSP switch is closed. The voltage signal is near battery voltage when the PSP switch is open.

Diagnostic Testing

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Connect scan tool. Start the engine. Run vehicle at idle with the accessories OFF, until normal operating temperature is reached. Monitor the IAC MOTOR COMMAND parameter on the scan tool while turning the rear defogger switch ON and OFF. Does the scan tool indicate IAC motor command increased 1-3 percent when the rear defogger switch was turned ON? If yes, go to next step. If no, go to step 18 .
3. Monitor the IAC MOTOR COMMAND parameter on the scan tool while turning the parking light switch ON and OFF. Does the scan tool indicate IAC motor command increased 1-3 percent when the parking light switch was turned ON? If yes, go to next step. If no, go to step 20 .
4. Monitor the IAC MOTOR COMMAND parameter on the scan tool. Turn the A/C switch ON and blower speed selector switch to any position except OFF. Does IAC motor command increase 4-14 percent when the A/C is turned ON? If yes, go to next step. If no, go to step 10 .
5. Monitor the IAC MOTOR COMMAND parameter on the scan tool. Turn the steering wheel to the right and to the left. Return steering wheel to the center, straight ahead position. Did the scan tool indicate IAC Motor Command increased 2-10 percent when the steering wheel was turned all the way in either direction? If yes, system is okay at this time. If no, go to next step.
6. Turn ignition switch to RUN position, engine OFF. Disconnect PSP switch harness connector. Measure voltage from PSP switch harness connector to ground using a DMM. Is voltage near battery voltage? If yes, go to next step. If no, go to step 8 .
7. Connect a test light to battery voltage. Probe PSP switch connector (component side) with the test light. Start the engine. Observe the test light while turning the steering wheel to the right and to the left. Does the test light illuminate when the steering wheel is turned to the right and to the left? If yes, go to step 22 . If no, go to step 9 .
8. Check for an open or a short to ground in the PSP switch signal circuit between PCM and PSP switch. Repair as necessary. Did you find and correct a condition? If yes, go to step 25 . If no, go to step 24 .
9. Check for a faulty ground connection at the power steering pump. Repair as necessary. Did you find and correct a condition? If yes, go to step 25 . If no, go to step 23 .
10. Start the engine. Turn ON the HVAC blower switch to any speed. Turn the A/C switch OFF. Is the A/C compressor clutch engaged? If yes, go to step 14 . If no, go to next step.
11. Continue to run the engine with HVAC blower ON and the A/C OFF. Backprobe the A/C clutch relay control circuit at the PCM connector using a DMM connected to ground. Measure the voltage. Does the voltage equal battery voltage? If yes, go to next step. If no, go to step 17 .
12. Turn A/C ON. Backprobe the A/C clutch relay control circuit at the PCM connector using a DMM connected to ground. Measure the voltage. Did the voltage drop to 0.0-1.0 volt when the A/C was turned ON? If yes, go to next step. If no, go to step 24
13. Did the A/C compressor engage when the A/C was turned ON? If yes, go to step 24 . If no, go to step 16 .
14. Check for a short to ground in the A/C clutch relay control circuit between PCM and A/C compressor clutch relay. Repair as necessary. Did you find and correct a condition? If yes, go to step 25 . If no, go to next step.
15. Turn ignition switch to OFF position. Disconnect PCM 35-pin harness connector C3. Start the engine. Turn ON the HVAC blower switch to any speed. Is the A/C compressor engaged? If yes, see appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
16. There is a fault in an HVAC electrical circuit or component. Inspect and repair as necessary. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. After repair, go to step 25 .
17. There is no ignition positive voltage at the A/C clutch relay control circuit. Check for an open in the A/C clutch relay control circuit between the PCM and the A/C compressor clutch relay or for a faulty A/C compressor clutch relay or repair the cause of no ignition positive voltage to the relay. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. After repair, go to step 25 .
18. Turn ignition switch to RUN position, engine OFF. Backprobe the electrical load idle-up signal defogger circuit at the PCM connector using a test light connected to ground. Turn rear defogger switch ON. Does the test light illuminate? If yes, go to step 22 . If no, go to appropriate REAR WINDOW DEFOGGERS article in ACCESSORIES & EQUIPMENT.
19. Turn ignition switch to OFF position. Check the electrical load idle-up signal defogger circuit for an open or a short. Repair as necessary. Did you find and correct a condition? If yes, go to step 25 . If no, go to step 21 .
20. Turn ignition switch to RUN position, engine OFF. Backprobe the electrical load idle-up signal taillights circuit at the PCM connector using a test light connected to ground. Turn parking lights ON. Does the test light illuminate? If yes, go to step 22 . If no, go to next step.
21. Turn ignition switch to OFF position. Test the electrical load idle-up signal taillights circuit for an open or a short. Repair as necessary. See «EXTERIOR LIGHTS»(ref-154446-S34086808792003080900000) in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If you found and corrected the condition, go to step 25 .
22. Test for a short to ground in the diagnostic request circuit from the PCM and the Data Link Connector (DLC). Repair as necessary. Did you find and correct a condition? If yes, go to step 25 . If no, go to step 24 .
23. Replace the PSP switch. After repair, go to 25 .
24. Replace the PCM. See «POWERTRAIN CONTROL MODULE»(ref-153233-S34445191712003032600000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to next step 25 .
25. Operate the vehicle within the conditions that the concern was first noticed. Does the system now operate properly? If yes, system is okay at this time. If no, go to «DIAGNOSTIC AIDS»(ref-152779-S28721471052003031200000) .

Check for any of the following conditions

1. The HIGH ELECTRICAL LOAD parameter on the scan tool can indicate if the PCM has received the rear defogger or parking lights ON signal. The scan tool should indicate Yes when the rear defogger or parking lights are turned ON and engine speed should increase slightly. Check for a malfunction in the IAC system or a short to ground in the Diagnostic Request circuit if the engine speed does not increase.
2. A malfunctioning rear defogger or parking light (taillight) circuit may cause erratic electrical load idle-up circuit performance. Check for a properly operating rear defogger or taillight system.
3. A PSP switch that does not close, or loss of ground at the PSP switch may cause the engine to stall when the power steering loads are high.
4. The scan tool will display A/C Request Signal YES when A/C is selected and the HVAC blower switch is ON at any speed. The scan tool will display A/C CLUTCH ON whenever the PCM is allowing A/C compressor engagement. Therefore the scan tool will also display A/C Clutch ON when any defrost mode is selected.

An intermittent malfunction may be caused by a fault in any one of the idle-up signal circuits. Check the wiring harness and components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.

1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(ref-152429-S10298708072003020400000) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
2. Using a scan tool, check for DTCs. Is DTC P0335 or P0340 set? If yes, go to «DTC P0335: CKP SENSOR CIRCUIT»(ref-152429-S17924903632003020400000) or «DTC P0340: CMP SENSOR CIRCUIT»(ref-152429-S25132080652003020400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 1.8L VIBE article. If no, go to next step.
3. Are DTCs P1300, P1305, P1310, or P1315 set? If yes, go to «DTC P1300, P1305, P1310, P1315: IGNITION COIL»(ref-152429-S09979277982003020400000) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 1.8L VIBE article. If no, go to next step.
4. Disconnect the harness connector of each fuel injector. Disconnect the harness connector at an ignition coil assembly. Remove the ignition coil assembly. Do not remove the spark plugs. Connect Spark Tester (J 26792), or equivalent, to the spark plug boot of the ignition coil assembly. Clip the spark tester to ground. Connect the coil assembly harness connector. Crank the engine and observe the spark tester. Repeat this test for each ignition coil assembly. Is a crisp Blue spark available at all ignition coil assemblies? If yes, go to step 7 . If no, go to next step.
5. Is a crisp Blue spark available at one or more ignition coil assemblies? If yes, go to next step. If no, go to step 9 .
6. Turn ignition switch to OFF position. Replace suspected faulty ignition coil with a known-good ignition coil. Repeat the test for spark using the Spark Tester. See step 4 . Was a crisp Blue spark present while cranking the engine? If yes, go to step 8 . If no, go to step 9 .
7. Inspect the ignition coil assembly boot and terminals for cracks, corrosion and carbon tracking Did you find any of the conditions? If yes, go to next step. If no, go to step 10 .
8. Replace the faulty ignition coil assembly or assemblies. After repair, go to step 10 .
9. Replace the PCM. After repair, go to step 10 .
10. Assemble the ignition system. Start the engine. Does the engine start and run? If yes, go to next step. If no, go to «ENGINE CRANKS BUT DOES NOT RUN»(ref-152426-S24080731382003032400000) under NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 1.8L VIBE article.
11. Check for DTCs. Are any DTCs set? If yes, go to «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-152429-S35671638322003020400000) in SELF-DIAGNOSTICS - 1.8L VIBE article.

Check for any of the following conditions

1. Any circuit malfunction between the ignition coil assembly and the PCM should set a fail safe circuit DTC P1300, P1305, P1310, or P1315.
2. Check the Crankshaft Position (CKP) sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan tool should indicate a steady 200-300 RPM while cranking. If erratic values, such as sudden spikes in the engine speed, are displayed, the engine reference signal is not stable enough for dependable ignition system operation.
3. An ignition system that tests OK after sitting may be susceptible to moisture. Spray water on the ignition system components and wiring in order to check for an intermittent failure.

EVAPORATIVE EMISSION CONTROL SYSTEM DIAGNOSIS

Note. Numbers in parenthesis correspond to numbered items in illustrations.

EVAP Canister Inspection

1. Remove the EVAP canister.
2. Visually inspect the EVAP canister, especially at the arrows, for any cracks or damage. (Scheme 68)
3. Plug the vent port (4). The vent port will remain plugged for all tests. (Scheme 69)
4. Block the purge port (3) closed. (Scheme 69)
5. Blow air with a pressure of 0.25 psi (1.7 kPa) into the EVAP vapor port (2). (Scheme 69)
6. Verify that air flows out of drain hose (1). (Scheme 69)
7. Block the purge port (3) and the drain hose (1) closed. (Scheme 70)
8. Blow air with a pressure of 0.25 psi (1.7 kPa) into the EVAP vapor port (4).
9. Verify that air does not flow out of the air inlet port (2). (Scheme 70)
10. Block the air inlet port (2) closed. (Scheme 71)
11. Connect Hand Vacuum Pump (J 23738-A), or equivalent, to the purge port (1). (Scheme 71)
12. Apply 1.0 in. Hg of vacuum to purge port (1) with the hand vacuum pump. (Scheme 71)
13. Verify that the vacuum holds while the air inlet port (2) is closed. (Scheme 71)
14. Open the air inlet port (2) and verify that the vacuum is released. (Scheme 71)
15. Block the air inlet port (1) closed. (Scheme 72)
16. Connect the hand vacuum pump to the EVAP vapor port (3). (Scheme 72)
17. Apply 1.0 in. Hg of vacuum to the EVAP port (3) using the hand vacuum pump. (Scheme 72)
18. Verify that there is vacuum pressure at the purge port (2). (Scheme 72)
19. Replace the EVAP canister if the canister failed any of the inspections or tests.

Scheme 68

Scheme 69

Scheme 70

Scheme 71

Scheme 72

EVAP Canister Purge Valve Inspection

1. Disconnect the EVAP vent solenoid electrical connector.
2. Using DMM, measure the solenoid resistance value. The resistance should be 25-30 ohms at 68°F (20°C). (Scheme 73)
3. Replace the solenoid if the resistance is not within the specification.
4. Using DMM, check for continuity between each solenoid terminal and solenoid housing. The DMM should read infinite (OL). (Scheme 74)
5. Replace the EVAP vent solenoid valve if the resistance is not within specification. A shorted valve will cause damage to the PCM.
6. Blow air through the upper port of the EVAP vent valve. Air has to flow freely through the lower port.
7. Replace the valve if the air does not flow through the upper port.
8. Apply battery voltage across the solenoid terminals. (Scheme 75)
9. Blow air through the upper port of the solenoid. Air should NOT flow through the valve. (Scheme 75)
10. Replace the solenoid if the solenoid fails any of the tests.

Scheme 73

Scheme 74

Scheme 75

EVAP Pressure Switching Solenoid Inspection

1. Remove the EVAP pressure switching solenoid.
2. Using DMM, measure the resistance of the EVAP pressure switching solenoid. (Scheme 76) The EVAP pressure switching solenoid resistance should be 37-44 ohms at 68°F (20°C).
3. Replace the EVAP pressure switching solenoid if the resistance is not as specified. The solenoid will damage the PCM, if the resistance value is less than 27 ohms.
4. Check for continuity on each terminal to the valve body. (Scheme 77)
5. Replace the EVAP pressure switching solenoid if continuity is present.
6. Blow air into the inboard port. The air should NOT flow through the valve and out of the outboard port.
7. Apply battery voltage across the terminals of the EVAP pressure switching solenoid. (Scheme 78)
8. Blow air into the inboard port and air should flow through the valve and out of the outboard port. (Scheme 78)
9. Replace the EVAP pressure switching solenoid if the solenoid failed either test.

Scheme 76

Scheme 77

Scheme 78

EVAP Canister Vent Valve Inspection

1. Disconnect the EVAP vent solenoid harness connector.
2. Using DMM, measure the solenoid resistance value. (Scheme 79) The resistance should be between 25-30 ohms at 68°F (20°C).
3. Replace the solenoid if the resistance is not within specification.
4. Using DMM, check for continuity between each solenoid terminal and solenoid housing. (Scheme 80) The DMM should read infinite (OL).
5. Replace the EVAP vent solenoid valve if the resistance is not within specification. A shorted valve will cause damage to the PCM.
6. Blow air through the upper port of the EVAP vent valve. Air has to flow freely through the lower port. (Scheme 81)
7. Replace the valve if the air does not flow through the upper port.
8. Apply battery voltage across the solenoid terminals. (Scheme 82)
9. Blow air through the upper port of the solenoid. Air should NOT flow through the valve. (Scheme 82)
10. Replace the solenoid if the solenoid fails any of the tests.

Scheme 79

Scheme 80

Scheme 81

Scheme 82

1. Drain the fuel tank.
2. Remove the fuel tank.
3. Plug the fuel feed hose, the fuel limiter vent valve hose, and the fuel tank vent valve hose on the fuel tank.
4. Plug the fuel filler neck opening.
5. Connect a piece of the hose to the breather hose nipple on the fuel tank and secure the hose with one clamp.
6. Submerge the fuel tank in water or apply a soapy solution to the outside of the tank.
7. Apply 1-2 psi (7-15 kPa) air pressure to the breather hose.
8. Air bubbles appearing from the fuel tank indicate a leak.
9. Replace the fuel tank if the tank is leaking.

Inspection/Diagnosis

1. Blow air into the cylinder head side of the PCV valve.
2. Check that air passes through the PCV valve easily.
3. Blow air into the intake manifold side of the PCV valve.
4. Check that air passes through the PCV valve with high resistances.
5. If the PCV valve fails either test, replace the PCV valve.