Engine Control System - 2.4L - Troubleshooting: Diagnosis Pontiac G6 I

Important Preliminary Inspections Before Starting

Before using the Symptom tables, perform the following

1. Perform «Diagnostic System Check - Vehicle»(ref-242980-S19231637582006082100000) and verify all of the following items: Ensure that the engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly. Ensure that there are no diagnostic trouble codes (DTCs) that are stored. Scan tool data is within a normal operating range. Refer to «Scan Tool Data List»(ref-243058-S21797621402006082100000) .
2. Verify the customer concern.
3. Perform the Visual/Physical Inspection in this article. The visual/physical inspection is extremely important and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.
4. Locate the correct symptom. Perform the tests and inspections associated with the symptom.

Symptoms

Use the following symptoms in order to isolate possible systems that are associated with the condition

Symptoms

Symptoms - Fuel System

Fuel System

Symptoms - Ignition System

Ignition System

Symptoms - Sensors/Systems

Sensor/System

Diagnostic Fault Information

Scan Tool Reference

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

Circuit/System Testing

1. Turn OFF the ignition.
2. Disconnect the ECM.
3. Turn ON the ignition with the engine OFF. If the MIL is still ON, test the MIL control circuit for a short to ground. If the MIL control circuit tested OK and the MIL stayed ON, replace the instrument panel cluster (IPC). If the MIL control circuit tested OK and the MIL went out when the ECM was disconnected, replace the ECM.
4. Measure for 12 volts from the MIL ignition voltage circuit in the IPC harness connector to a ground. If there is less than 12 volts, test the MIL ignition voltage circuit for an open or a short to ground and an open fuse.
5. Remove the fuse that supplies voltage to the MIL.
6. Measure for less than one volt from the MIL control circuit in the ECM harness connector to a good ground. If there is more than one volt, test the MIL control circuit for a short to voltage.
7. Install the fuse that supplies voltage to the MIL.
8. The MIL should illuminate with a 3-amp fused jumper wire connected between the MIL control circuit in the ECM harness connector and a good ground. If the MIL does not illuminate, test the MIL control circuit for an open or high resistance. If the MIL control circuit tests OK, replace the IPC. If the MIL does illuminate, but does not when commanded ON with a scan tool, replace the ECM.

Scan Tool Data List

1. Crank the engine for up to 30 seconds.
2. Observe the Engine DTC information with a scan tool. If any of the following DTCs are set refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(ref-242980-S20451683192006082100000) to diagnose those DTCs: P0201-P0206, P0335, P0336, P0351-P0353, P0601, P0602, P0603, P0604, P0606, P0607, P060E, P062F, P0685, P0689, P0690, P1516, P2610.
3. Observe the engine speed parameter while cranking the engine. If engine RPM is not indicated, refer to «Electronic Ignition (EI) System Diagnosis»(ref-243024-S04142705972006082100000) .
4. Install a spark tester.
5. Crank the engine for 15 seconds. Spark should be observed from the Spark Tester. If spark is not observed refer to «Electronic Ignition (EI) System Diagnosis»(ref-243024-S04142705972006082100000) .
6. With the ignition ON and the engine OFF, test the fuses that are supplied by the powertrain relay for voltage. The test lamp should illuminate at each fuse test point. Emission Fuse Ignition 1 Fuse If the test lamp does not illuminate on at least one side of each fuse refer to «DTC P0685, P0689 or P0690»(ref-243046-S19740573312006082100000) .
7. Command the fuel pump ON and OFF. Fuel pump should energize when commanded ON and De-energize when commanded OFF If the fuel pump does not respond refer to «Fuel Pump Electrical Circuit Diagnosis»(ref-243024-S03838306852006082100000) .
8. Turn OFF the ignition.
9. Install the J 34730-1A Fuel Pressure Gage. See «Special Tools»(ref-243018-S23371870782006082100000) . Turn ON the ignition and command the fuel pump ON while observing the J 34730-1A . See «Special Tools»(ref-243018-S23371870782006082100000) . The fuel pressure should be between 345-414 kPa (50-60 psi). If the fuel pressure is not within 345-414 kPa (50-60 psi) refer to «Fuel System Diagnosis»(ref-243024-S36811191122006082100000) .
10. Inspect for the following conditions: Compare the actual engine coolant temperature to the ECT parameter. Air filter and air intake system for restrictions and obstructions Test the fuel for contamination. Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(ref-243024-S18668824392006082100000) . Inspect the spark plug and spark plug wires. Refer to «Spark Plug Inspection»(ref-243018-S31525763092006082100000) . Test the exhaust system for restrictions. Refer to «Restricted Exhaust»(ref-243054-S19494961302006082100000) .

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Fuel Pump Electrical Circuit Diagnosis

Diagnostic Aids

The following conditions may cause the fuel pump fuse to open

1. The fuse is faulty.
2. There is an intermittent short to ground in the supply voltage circuit of the fuel pump.
3. The fuel pump has an intermittent internal condition.

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Data Definitions»(ref-243058-S42715658802006082100000)
3. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

1. With the ignition OFF, remove the fuel pump relay from the rear electrical center.
2. With the ignition ON, engine OFF, probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF with each command. If the test lamp does not turn ON and OFF, test for an open, high resistance or a short to ground in the fuel pump relay control circuit, an intermittent or a poor connection at the engine control module (ECM) or a faulty ECM. If the test lamp remains illuminated with each command, test for a short to voltage in the control circuit of the fuel pump relay, an intermittent or a poor connection at the ECM or a faulty ECM.
3. Connect a test lamp between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. Command the fuel pump relay ON and OFF with a scan tool. If the test lamp does not turn ON and OFF, repair the open or the high resistance in the ground circuit of the fuel pump relay. If the test lamp does turn ON and OFF, test for an intermittent and for a poor connection at the fuel pump relay or a faulty fuel pump relay.
4. Inspect the fuel pump fuse. If the fuel pump fuse is open, test for a short to ground in the supply voltage circuit of the fuel pump or a faulty fuel sender.
5. With the ignition ON, engine OFF, probe the battery positive voltage circuit of the fuel pump relay with a test lamp that is connected to a good ground. If the test lamp does not illuminate, repair the open in the battery positive voltage circuit.
6. Connect a 15-amp fused jumper wire between the battery positive voltage circuit of the fuel pump relay and the supply voltage circuit of the fuel pump. If the fuel pump operates, test for an intermittent or poor connection at the fuel pump relay or a faulty fuel pump relay. If the fuel pump does not operate, test for an open or high resistance in the supply voltage circuit of the fuel pump, an open or high resistance in the ground circuit of the fuel pump, an intermittent or poor connection at the fuel sender cover or a faulty fuel sender.

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Data Definitions»(ref-243058-S42715658802006082100000)
3. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

1. Turn OFF the ignition.
2. Relieve the fuel pressure. Refer to «Fuel Pressure Relief Procedure»(ref-243018-S31153521452006082100000) .
3. Disconnect the chassis fuel hose from the engine compartment fuel pipe. Refer to «Quick Connect Fitting(s) Service (Metal Collar)»(ref-243018-S29713473812006082100000) .
4. Install the J 37287 between the chassis fuel hose and the engine compartment fuel pipe. See «Special Tools»(ref-243018-S23371870782006082100000) .
5. Open the valve on the J 37287 . See «Special Tools»(ref-243018-S23371870782006082100000) .
6. Turn ON the ignition, with the engine OFF.
7. Command the fuel pump relay ON with a scan tool.
8. Bleed the air from the J 34730-1A . See «Special Tools»(ref-243018-S23371870782006082100000) .
9. Command the fuel pump relay ON and then OFF with a scan tool.
10. Close the fuel feed pipe shut-off valve.
11. Monitor the J 34730-1A for one minute. See «Special Tools»(ref-243018-S23371870782006082100000) . If the fuel pressure remains constant, replace the fuel sender assembly. If the fuel pressure does not remain constant, locate and replace the leaking fuel injectors.

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

1. Monitoring the misfire current counters or misfire graph, may help to isolate the fuel injector that is causing the condition.
2. Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
3. Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature or under certain conditions.

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Data Definitions»(ref-243058-S42715658802006082100000)
3. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

Fuel Injector Coil Test

1. Observe the ECT Sensor parameter with a scan tool. The ECT sensor should be 10-32°C (50-90°F). If the ECT Sensor parameter is not within 10-32°C (50-90°F), go to step 3.
2. Measure the resistance of each fuel injector with a DMM. The resistance of each fuel injector should be 11-14 ohms. If the resistance of any fuel injector is not 11-14 ohms, replace the fuel injector.
3. Measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohms. If the difference is equal to or less than 3 ohms, perform the Fuel Injector Balance Test-Fuel Pressure Test. If the difference is more than 3 ohms, continue with the Fuel Injector Coil Test.
4. 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 individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the fuel injector that displays the greatest resistance difference above or below the average.
5. Perform the Fuel Injector Balance Test-Fuel Pressure Test.

Fuel Injector Balance Test-Fuel Pressure Test

1. Install a fuel pressure gage. Refer to «Fuel Pressure Gage Installation and Removal»(ref-243018-S08410414972006082100000) .
2. Turn ON the ignition, with the engine OFF.
3. Command the fuel pump relay ON with a scan tool.
4. Observe the fuel pressure gage with the fuel pump commanded ON. The fuel pressure should be 345-414 kPa (50-60 psi). If the fuel pressure is not 345-414 kPa (50-60 psi), refer to «Fuel System Diagnosis»(ref-243024-S36811191122006082100000) .
5. Monitor the fuel pressure gage for one minute. The fuel pressure should not decrease more than 34 kPa (5 psi). If the fuel pressure decreases more than 34 kPa (5 psi), refer to «Fuel System Diagnosis»(ref-243024-S36811191122006082100000) .
6. Perform the Fuel Injector Balance Test with Special Tool or the Fuel Injector Balance Test with Tech 2.

Fuel Injector Balance Test with Special Tool

1. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
2. Connect the J 39021 to a fuel injector with a J 44602 . See «Special Tools»(ref-243018-S23371870782006082100000) .
3. Command the fuel pump relay ON and then OFF with a scan tool.
4. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the first pressure reading.
5. Energize the fuel injector by depressing the Push to Start Test button on the fuel injector tester.
6. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the second pressure reading.
7. Repeat steps 2-6 for each fuel injector.
8. Perform the Pressure Drop Calculation.

Fuel Injector Balance Test with Tech 2

1. With a scan tool, select the Fuel Injector Balance Test function within the Special Functions menu.
2. Select an injector to be tested.
3. Press Enter to prime the fuel system.
4. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the first pressure reading.
5. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure.
6. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the second pressure reading.
7. Press Enter again to bring you back to the Select Injector screen.
8. Repeat steps 2-7 for each fuel injector.
9. Perform the Pressure Drop Calculation.

Fuel Injector Circuit Diagnosis

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Data Definitions»(ref-243058-S42715658802006082100000)
3. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

1. Inspect the INJ fuse. If the fuse is open, repair the short to ground in the ignition 1 voltage circuit of the fuel injectors.
2. Remove the air cleaner outlet resonator. Refer to «Air Cleaner Outlet Resonator Replacement»(ref-243018-S31958997662006082100000) .
3. Disconnect a fuel injector.
4. With the ignition ON, engine OFF, probe the ignition 1 voltage circuit of the fuel injector with a test lamp that is connected to a good ground. The test lamp should illuminate. If the test lamp does not illuminate, repair the open in the ignition 1 voltage circuit between the fuse and the splice.
5. Remove the INJ fuse.
6. Measure the resistance between the INJ fuse to the ignition 1 voltage circuit terminal of a fuel injector with a DMM. All wire circuit resistance should measure less than 2 ohms. If the resistance is more than 2 ohms, repair the high resistance in the ignition 1 voltage circuit.
7. Connect the J 44603 into each fuel injector connector one at a time. See «Special Tools»(ref-243018-S23371870782006082100000) . Crank the engine. If the test lamp flashes for each injector, perform the Fuel Injector Diagnosis. Refer to «Fuel Injector Diagnosis»(ref-243024-S10696391132006082100000) . If the test lamp does not flash for each injector, test for an open or a short to voltage in the control circuit of the fuel injector, an intermittent or poor connection at the engine control module (ECM) or a faulty ECM. If the test lamp remains illuminated at all times for any injector circuit, test for a short to ground in the control circuit of the fuel injector or a faulty ECM.

Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

1. Operate the vehicle under the condition of the customer concern. Under high temperature conditions fuel vapors may increase to the point of EVAP canister vapor saturation. Fuel vapors would then be released into the atmosphere. Once the engine is running and the EVAP purge is enabled, all fuel vapor release would be eliminated.
2. Movement of the EVAP pipes or the fuel pipes may help find an intermittent condition.
3. If the fuel level is low, a liquid fuel leak may not be evident.

System Testing

1. Turn OFF the ignition. Install the J 41413-200 and the GE-41415-50 . See «Special Tools»(ref-243018-S23371870782006082100000) . Test for a fuel leak while the system is under pressure referring to the J 41413-210 Operation Manual.
2. Using the J 41413-200 and the J 41413-210 Operation Manual, introduce smoke into the evaporative emission (EVAP) system. See «Special Tools»(ref-243018-S23371870782006082100000) . Inspect for leaks in any of the following locations: The fuel tank, the fill limiter vent valve, the pressure relief valve and the grade vent valves The fuel sender housing, the fuel sender seal, the fuel pipe and the EVAP pipes The fuel tank pressure (FTP) sensor seal The fuel fill pipe and hose

Alcohol in Fuel Testing with Special Tool

1. Test the fuel composition using J 44175 and Instruction Manual. See «Special Tools»(ref-243018-S23371870782006082100000) .
2. If water appears in the fuel sample, clean the fuel system.
3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
4. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
5. Test the fuel composition.
6. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle.

Alcohol in Fuel Testing without Special Tool

1. Using a 100 ml (3.38 oz.) specified cylinder with 1 ml (0.034 oz.) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz.) mark.
2. Add 10 ml (0.34 oz.) of water in order to bring the total fluid volume to 100 ml (3.38 oz.) and install a stopper.
3. Shake the cylinder vigorously for 10-15 seconds.
4. Carefully loosen the stopper in order to release the pressure.
5. Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
6. Put the cylinder on a level surface for approximately 5 minutes in order to allow adequate liquid separation. If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 10 ml (0.34 oz.). For example, if the volume of the lower layer is increased to 15 ml (0.51 oz.), this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

1. Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel.
2. Place the container on a level surface for approximately 5 minutes in order to allow settling of the particulate contamination. Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a white or light brown crystals. Rubber will appear as black and irregular particles.
3. Observe the fuel sample. If any physical contaminants or water are present, clean the fuel system.

1. «Scan Tool Data List»(ref-243058-S21797621402006082100000)
2. «Scan Tool Output Controls»(ref-243058-S05467689912006082100000)

1. Turn OFF the ignition.
2. Inspect the fuse that supplies voltage to the ignition coil/modules. If the fuse is open, then test the spliced circuits and the individual ignition coil/modules for a short to ground.
3. Disconnect the affected ignition coil/module.
4. Connect a test lamp between the ignition coil/module ignition 1 voltage circuit and a good ground.
5. With the test lamp still connected, measure for battery voltage between the ignition 1 voltage circuit and a good ground. If the voltage is not within 1 volt of battery voltage, repair the high resistance or the open in the ignition 1 voltage circuit.
6. Turn OFF the ignition and all electrical accessories. Allow sufficient time for all of the control modules to power down before taking a resistance measurement.
7. Measure for a proper value of less than 5 ohms of resistance between the ground circuit of the affected ignition coil/module and a good ground. If the resistance is more than 5 ohms, repair the high resistance or the open in the ground circuit.
8. Exchange the affected ignition coil/module with the ignition coil/module of a good cylinder.
9. Start the engine and observe the scan tool. If the misfire transfers with the suspect ignition coil/module, replace as needed. If the misfire does not transfer with the suspect ignition coil/module, observe the component testing procedures below and replace the spark plug if needed.

Component Testing

1. Use the Spark Plug Inspection procedure to verify the integrity of the spark plugs. Refer to «Spark Plug Inspection»(ref-243018-S31525763092006082100000) .
2. Use the J 26792 Spark Tester to verify the output of each ignition coil/module. See «Special Tools»(ref-243018-S23371870782006082100000) .

1. Observe the Engine DTC information with a scan tool. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. Refer to «Inspection/Maintenance (I/M) System DTC Table»(ref-243024-S12458620042006082100000) .
2. Review applicable service bulletins for software updates that would prevent the I/M System Status tests from completing. If a control module re-program or other repair is required, perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(ref-243024-S33143101872006082100000) .
3. Observe the I/M System Status indicators. If any I/M System Status indicators report NO, perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(ref-243024-S33143101872006082100000) .

Inspection/Maintenance (I/M) System Set Procedure

1. Ensure that the vehicle meets the conditions for a cold start listed above. If the evaporative emission (EVAP) I/M System Status indicator displays NO, perform the EVAP Service bay test if applicable. If the EVAP Service Bay Test is NOT available, it may take up to 6 drive cycles, with up to 17 hours between drive cycles, for the EVAP I/M System Status indicator to transition to YES. If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
2. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc.
3. Set the vehicle parking brake and ensure the vehicle is in park for automatic transmission or neutral for manual transmission.
4. Turn the ignition ON with the engine OFF for one minute.
5. Start and idle the engine for 2 minutes and until 65°C (149°F) is achieved.
6. Run the engine for 8 minutes within the following conditions: MAF parameter between 4-30 g/s Engine speed steady between 1,000-3,000 RPM
7. Apply and hold brake pedal and shift to Drive for automatic or apply clutch pedal for manual and operate the vehicle within the following conditions for 2 minutes: Mass air flow (MAF) signal between 15-30 g/s RPM steady between 1,200-1,500 RPM
8. Release the accelerator pedal and allow the engine to idle for 2 minutes.
9. Release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
10. Continue to drive the vehicle for at least 5.5 miles between 45 km/h-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
11. Safely stop the vehicle, apply the parking brake and shift to Park for automatic or Neutral and release clutch pedal for manual.
12. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 45 minutes.
13. Observe the I/M System Status with a scan tool. All of the I/M System Status indicators should display YES. If the EVAP I/M System Status indicator displays NO turn OFF the ignition for 17 hours, ensure that the vehicle meets the conditions for a cold start and repeat steps 10-13 six more times or until the EVAP I/M System Status indicator transitions to YES. If the indicator continues to display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(ref-243024-S12458620042006082100000) to identify the DTCs that did not run.

1. If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(ref-243024-S12458620042006082100000) for the indicator which did not display YES. The I/M System DTC Table identifies the DTCs associated with each I/M System Status Indicator.

Inspection/Maintenance (I/M) System DTC Table

Inspection/Maintenance (I/M) System DTC Table