MIL Operation
The MIL is located on the instrument panel cluster (IPC).
MIL Function
- The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
- The MIL illuminates during a bulb test and a system test.
- A DTC will be stored if a MIL is requested by the PCM.
MIL Illumination
- The MIL will illuminate with ignition switch ON and the engine not running.
- The MIL will turn OFF when the engine is started.
- The MIL will remain ON if the self-diagnostic system has detected a malfunction.
- The MIL may turn OFF if the malfunction is not present.
- If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
- If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.
Test Description
The number below refers to the step number on the diagnostic table.
- 4: This step tests for a short to voltage on the MIL control circuit. With the fuse removed there should be no voltage on the MIL control circuit.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | Command the malfunction indicator lamp (MIL) ON and OFF with a scan tool. Does the MIL turn ON and OFF when commanded with a scan tool? | Go to Intermittent Conditions | Go to Step 3 | |
| 3 | Inspect the fuse that supplies ignition voltage to the cluster. Is the fuse open? | Go to Step 10 | Go to Step 4 | |
| 4 | Turn OFF the ignition. Remove the fuse that supplies voltage to the cluster. Disconnect the powertrain control module (PCM). Turn ON the ignition with the engine OFF. Measure the voltage from the MIL control circuit in the PCM harness connector to a good ground. Is the voltage less than the specified value? | 0.3 V | Go to Step 5 | Go to Step 11 |
| 5 | Turn OFF the ignition. Install the fuse that supplies voltage to the cluster. Turn ON the ignition with the engine OFF. Connect a 3-amp fused jumper wire between the MIL control circuit in the PCM harness connector and a good ground. Is the MIL illuminated? | Go to Step 9 | Go to Step 6 | |
| 6 | Turn OFF the ignition. Remove the instrument panel cluster (IPC). Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Probe the ignition voltage circuit of the IPC harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 7 | Go to Step 12 | |
| 7 | Test the MIL control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 15 | Go to Step 8 | |
| 8 | Test for an intermittent and for a poor connection at the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 13 | |
| 9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 14 | |
| 10 | Repair the short to ground in the ignition voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 15 | ||
| 11 | Repair the short to voltage in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 15 | ||
| 12 | Repair the open in the ignition voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 15 | ||
| 13 | Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | Go to Step 15 | ||
| 14 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 15 | ||
| 15 | Turn OFF the ignition for 30 seconds. Does the vehicle operate correctly, without any MIL illumination and without any stored DTCs? | System OK | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | |
Malfunction Indicator Lamp (MIL) Inoperative
The MIL is located on the instrument panel (IPC).
MIL Function
- The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
- The MIL illuminates during a bulb test and a system test.
- A DTC will be stored if a MIL is requested by the diagnostic.
MIL Illumination
- The MIL will illuminate with ignition switch ON and the engine not running.
- The MIL will turn OFF when the engine is started.
- The MIL will remain ON if the self-diagnostic system has detected a malfunction.
- The MIL may turn OFF if the malfunction is not present.
- If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated so long as the ignition switch is ON.
- If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.
The number below refers to the step number on the diagnostic table.
- 2: This step determines if the condition is with the MIL control circuit or the PCM.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Turn OFF the ignition. Disconnect the powertrain control module (PCM). Turn ON the ignition, with the engine OFF. Observe the malfunction indicator lamp (MIL). Is the MIL illuminated? | Go to Step 3 | Go to Step 5 |
| 3 | Remove the instrument panel cluster (IPC). Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Test the MIL control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 4 |
| 4 | Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | Go to Step 6 | |
| 5 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | |
| 6 | Turn the ignition OFF for 30 seconds. Start the engine. Does the vehicle operate correctly without any MIL illumination, and without any stored DTCs? | System OK | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information |
Malfunction Indicator Lamp (MIL) Always On
Description
The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine not to start. The Engine Cranks but Does Not Run diagnostic table directs the service technician to the appropriate system diagnosis.
The Engine Cranks but Does Not Run diagnostic table assumes the following
- The battery is completely charged. Refer to «Battery Inspection/Test (Non-HP2)»(ref-200375-S31674730592005102000000) in Engine Electrical.
- The cranking speed is acceptable. Refer to «Engine Cranks Slowly»(ref-200375-S21396983362005102000000) in Engine Electrical.
- There is adequate fuel in the fuel tank.
The number below refers to the step number on the diagnostic table.
- 8: The crankshaft position (CKP) sensor can fail in such a way that will cause the engine to crank but will not run. The engine will be able to run by using the cam sensor when the CKP sensor is disconnected.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | Turn ON the ignition, with the engine OFF. With a scan tool, observe the DTC information. Does the scan tool display DTCs P0068, P0107, P0601, P0602, P0604, P0606, P0607, P0651, P1621, P1631, P1680, P1681, or P1682? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 | |
| 3 | Does the scan tool display any body control module (BCM) vehicle theft deterrent (VTD) DTCs? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 4 | |
| 4 | Command the fuel pump ON with a scan tool. Does the fuel pump turn ON? | Go to Step 5 | Go to Fuel Pump Electrical Circuit Diagnosis | |
| 5 | Turn OFF the ignition. Remove an ignition coil. Refer to Ignition Coil(s) Replacement . Install the J 26792 Spark Tester to the coil boot. See Special Tools . Attempt to start the engine. Does the spark tester spark? | Go to Step 6 | Go to Electronic Ignition (EI) System Diagnosis | |
| 6 | Turn OFF the ignition. Disconnect the multi-way harness connector of the fuel injectors. Connect a test lamp between the ignition 1 voltage circuit of the fuel injector, fuse side, and a fuel injector control circuit, powertrain control module (PCM) side. Crank the engine. Does the test lamp flash when cranking the engine? | Go to Step 7 | Go to Fuel Injector Circuit Diagnosis | |
| 7 | Turn OFF the ignition. Install the J 34730-1A Fuel Pressure Gage. See Special Tools . Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. Is the fuel pressure within the specified range while the fuel pump is operating? | 334-375 kPa (48-54 psi) | Go to Step 8 | Go to Fuel System Diagnosis |
| 8 | Disconnect the crankshaft position (CKP) sensor. Attempt to start the engine. Does the engine start and continue to run? | Go to Step 10 | Go to Step 9 | |
| 9 | Inspect for the following conditions: A collapsed air intake duct A restricted air filter element-Refer to Air Cleaner Element Replacement . Contaminated fuel-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) . The spark plugs for being gas or coolant fouled-Refer to Spark Plug Inspection . If the spark plugs are fouled, determine what caused the condition. An engine mechanical condition (worn timing chain, gears and low compression)-Refer to Symptoms - Engine Mechanical in Engine Mechanical. A restricted exhaust system-Refer to Restricted Exhaust in Engine Exhaust. An engine coolant temperature (ECT) sensor that has shifted in value. Refer to Temperature vs Resistance . Compare MAP/BARO parameters to another vehicle. The parameters should be close in value. Refer to Altitude vs Barometric Pressure . Did you complete the action? | Go to Step 11 | ||
| 10 | Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement . Did you complete the replacement? | Go to Step 11 | Go to Step 2 | |
| 11 | Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Attempt to start the engine. Does the engine start and continue to run? | Go to Step 12 | Go to Step 2 | |
| 12 | Allow the engine to reach operating temperature. Observe the DTC information with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |
Engine Cranks but Does Not Run
System Description
The fuel system is a returnless on-demand design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.
An electric turbine style fuel pump attaches to the fuel sender assembly inside the fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pressure regulator, a part of the fuel sender assembly, maintains the correct fuel pressure to the fuel injection system. The fuel pump and sender assembly contains a reverse flow check valve. The check valve and the fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | IMPORTANT: Inspect the fuel system for damage or external leaks before proceeding with this diagnostic. Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON with a scan tool. Does the fuel pump operate? | Go to Step 3 | Go to Fuel Pump Electrical Circuit Diagnosis | |
| 3 | IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Turn OFF the ignition. Turn OFF all accessories. Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. Command the fuel pump relay ON with a scan tool. Observe the fuel pressure gage with the fuel pump commanded ON. Is the fuel pressure within the specified range? | 345-395 kPa (50-57 psi) | Go to Step 4 | Go to Step 8 |
| 4 | IMPORTANT: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute.Does the fuel pressure decrease by more than the specified value? | 34 kPa (5 psi) | Go to Step 7 | Go to Step 5 |
| 5 | Relieve the fuel pressure to the first specified value. Monitor the fuel pressure gage for 5 minutes. Does the fuel pressure decrease by more than the second specified value? | 69 kPa (10 psi) 14 kPa (2 psi) | Go to Step 12 | Go to Step 6 |
| 6 | Operate the vehicle within the conditions to reproduce the original symptoms. Monitor the O2 and the fuel trim parameters with a scan tool. Do any of the scan tool parameters indicate a lean condition? | Go to Step 9 | Go to Symptoms - Engine Controls | |
| 7 | Turn OFF the ignition. Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure . Disconnect the fuel feed hose from the fuel rail pipe. Refer to Quick Connect Fitting(s) Service (Metal Collar) . Install the J 37287 Fuel Line Shut-off Adapter between the fuel hose and the fuel rail pipe. See Special Tools . Open the valve on the fuel pipe shut-off adapter. Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON with a scan tool. Bleed the air from the fuel pressure gage. Command the fuel pump relay ON and then OFF with a scan tool. Close the fuel feed pipe shut-off valve. Monitor the fuel pressure gage for 1 minute. Does the fuel pressure remain constant? | Go to Step 12 | Go to Step 11 | |
| 8 | Is the fuel pressure more than the specified value? | 395 kPa (57 psi) | Go to Step 12 | Go to Step 9 |
| 9 | Inspect the fuel feed pipe for a restriction. Did you find and correct the condition? | Go to Step 13 | Go to Step 10 | |
| 10 | Inspect the harness connectors and the ground circuits of the fuel pump for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 | |
| 11 | Turn OFF the ignition. Raise the fuel rail with the fuel pipe connected. Refer to Fuel Rail Assembly Replacement . Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON with a scan tool. Locate and replace the leaking fuel injector. Refer to Fuel Injector Replacement . Did you complete the replacement? | Go to Step 13 | ||
| 12 | Replace the fuel sender. Refer to Fuel Sender Assembly Replacement . Did you complete the replacement? | Go to Step 13 | ||
| 13 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| Inspect the fuel system for damage or external leaks before proceeding with this diagnostic. |
| IMPORTANT |
|---|
| Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. |
| IMPORTANT |
|---|
| The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. |
| IMPORTANT |
|---|
| The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. |
Fuel System Diagnosis
The scan tool is first used to energize the fuel pump relay. The fuel injector tester is then used to pulse each injector for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
| Cylinder | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| 1st Reading | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi) |
| 2nd Reading | 280 kPa (41 psi) | 310 kPa (45 psi) | 340 kPa (49 psi) | 317 kPa (46 psi) |
| Amount of Drop | 99 kPa (14 psi) | 69 kPa (10 psi) | 39 kPa (6 psi) | 62 kPa (9 psi) |
| Average Range: 47-87 kPa (6.8-12.6 psi) | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop | Injector OK |
Fuel Injector Balance Test Example (Actual Results May Vary)
The number below refers to the step number on the diagnostic table.
- 3: The engine coolant temperature (ECT) must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | Did you perform the Fuel Injector Coil Test? | Go to Step 3 | Go to Fuel Injector Coil Test | |
| 3 | IMPORTANT: DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Observe the ECT Sensor parameter with a scan tool.Is the ECT Sensor parameter less than the specified value? | 94°C (201°F) | Go to Step 4 | |
| 4 | IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Turn OFF the ignition. Turn OFF all accessories. Install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump relay may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure. DO NOT start the engine. Command the fuel pump relay ON with a scan tool. Observe the fuel pressure gage, with the fuel pump operating. Is the fuel pressure within the specified range? | 345-395 kPa (50-57 psi) | Go to Step 5 | Go to Fuel System Diagnosis |
| 5 | IMPORTANT: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute.Does the fuel pressure decrease by more than the specified value? | 34 kPa (5 psi) | Go to Fuel System Diagnosis | Go to Step 6 |
| 6 | NOTE: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding. Disconnect the multi-way harness connector of the fuel injectors. Connect the J 39021 Fuel Injector Tester to the ignition 1 voltage circuit terminal and the appropriate fuel injector control circuit terminal using the J 35616 Connector Test Adapter Kit. Refer to Inline Harness Connector End Views in Wiring Systems. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position. Command the fuel pump relay ON and then OFF with a scan tool. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the first pressure reading. IMPORTANT: The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. 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 gage after the fuel injector has stopped pulsing. This is the second pressure reading. Repeat items 2-7 for each fuel injector. Subtract the second pressure reading from the first 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. Is the difference between any individual pressure drop and the average pressure drop more than the specified value? | 20 kPa (3 psi) | Go to Step 7 | Go to Symptoms - Engine Controls |
| 7 | Perform Fuel Injector Cleaning Procedure . Did you complete the procedure? | Go to Step 8 | ||
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Symptoms - Engine Controls |
| IMPORTANT |
|---|
| DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). |
| IMPORTANT |
|---|
| Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. |
| IMPORTANT |
|---|
| The fuel pump relay may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure. DO NOT start the engine. |
| IMPORTANT |
|---|
| The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. |
| NOTE |
|---|
| Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding. |
| IMPORTANT |
|---|
| The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. |
Fuel Injector Balance Test with Special Tool
The scan tool is first used to energize the fuel pump relay. The scan tool is then used to pulse each injector for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
| Cylinder | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| 1st Reading | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi) | 379 kPa (55 psi) |
| 2nd Reading | 280 kPa (41 psi) | 310 kPa (45 psi) | 340 kPa (49 psi) | 317 kPa (46 psi) |
| Amount of Drop | 99 kPa (14 psi) | 69 kPa (10 psi) | 39 kPa (6 psi) | 62 kPa (9 psi) |
| Average Range: 47-87 kPa (6.8-12.6 psi) | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop | Injector OK |
Fuel Injector Balance Test Example (Actual Results May Vary)
The number below refers to the step number on the diagnostic table.
- 3: The engine coolant temperature (ECT) must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | Did you perform the Fuel Injector Coil Test? | Go to Step 3 | Go to Fuel Injector Coil Test | |
| 3 | IMPORTANT: DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Observe the ECT Sensor parameter with a scan tool.Is the ECT Sensor parameter less than the specified value? | 94°C (201°F) | Go to Step 4 | |
| 4 | IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Turn OFF the ignition. Turn OFF all accessories. Install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. Command the fuel pump relay ON with a scan tool. Observe the fuel pressure gage, with the fuel pump operating. Is the fuel pressure within the specified value? | 345-395 kPa (50-57 psi) | Go to Step 5 | Go to Fuel System Diagnosis |
| 5 | IMPORTANT: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute.Does the fuel pressure decrease by more than the specified value? | 34 kPa (5 psi) | Go to Fuel System Diagnosis | Go to Step 6 |
| 6 | With a scan tool, select the Fuel Injector Balance Test function, within the Special Functions menu. Select an injector to be tested. Press Enter. This will prime the fuel system. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the 1st pressure reading. IMPORTANT: Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. Energize the fuel injector by depressing the Pulse Injector button on the scan tool. This will energize the injector and decrease the fuel pressure. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the 2nd pressure reading. Press Enter again to bring you back to the Select Injector screen. Repeat 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. Is the difference between any individual pressure drop and the average pressure drop more than the specified value? | 20 kPa (3 psi) | Go to Step 7 | Go to Symptoms - Engine Controls |
| 7 | Perform the Fuel Injector Cleaning Procedure . Did you complete the procedure? | Go to Step 8 | ||
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Symptoms - Engine Controls |
| IMPORTANT |
|---|
| DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). |
| IMPORTANT |
|---|
| Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. |
| IMPORTANT |
|---|
| The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. DO NOT start the engine. |
| IMPORTANT |
|---|
| The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. |
| IMPORTANT |
|---|
| Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. |
Fuel Injector Balance Test with Tech 2
The fuel tank leak test is used to locate any fuel or fuel vapor escaping the fuel tank area. Fuel vapors escaping above the fuel level will be detected, if more than the calibrated amount, when the evaporative emission (EVAP) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics have failed 2 test cycles.
The numbers below refer to the step numbers on the diagnostic table.
- 4: This step tests for fuel leaks below the fuel tank fuel level.
- 5: This step tests for fuel vapors escaping above the fuel level in the fuel tank.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | CAUTION: Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Inspect the fuel tank and the fuel pipes for damage or external leaks. Did you find fuel leaking from the fuel tank? | Go to Step 6 | Go to Step 3 |
| 3 | Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON with a scan tool. Inspect for fuel leaking from the fuel pipes. Did fuel leak from the fuel pipes? | Go to Step 7 | Go to Step 4 |
| 4 | Turn OFF the ignition. Install J 41413-200 Evaporative Emissions System Tester (EEST) and J 41415-40 Fuel Tank Cap Adapter or GE-41415-50 Interrupted Thread Cap Adapter. See Special Tools . Test for a fuel tank leak referring to the J 41413-210 Operation Manual. IMPORTANT: If the floating indicator registers any flow after stabilizing, a leak is evident. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information. Inspect for a fuel leak while the system is under pressure. Did fuel leak from the fuel tank? | Go to Step 6 | Go to Step 5 |
| 5 | Using the J 41413-200 and the J 41413-210, introduce smoke into the evaporative emission (EVAP) system. See Special Tools . IMPORTANT: It may be necessary to partially lower the fuel tank. Refer to Fuel Tank Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Tank Replacement (TrailBlazer, Envoy, Rainier) . 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-Refer to Fuel Tank Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Tank Replacement (TrailBlazer, Envoy, Rainier) . The fuel sender housing and fuel sender seal-Refer to Fuel Sender Assembly Replacement . The fuel tank pressure (FTP) sensor seal-Refer to Fuel Tank Pressure Sensor Replacement . The EVAP pipes-Refer to Evaporative Emission (EVAP) Hoses/Pipes Replacement - Canister/Fuel Tank (TrailBlazer, Envoy, Rainier) or Evaporative Emission (EVAP) Hoses/Pipes Replacement - Canister/Fuel Tank (TrailBlazer EXT, Envoy XL, Envoy XUV) . The fuel fill pipe and hose-Refer to Fuel Tank Filler Pipe Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Tank Filler Pipe Replacement (TrailBlazer, Envoy, Rainier) . Did you find and correct the condition? | Go to Step 8 | Go to Diagnostic Aids |
| 6 | Replace the fuel tank. Refer to Fuel Tank Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Tank Replacement (TrailBlazer, Envoy, Rainier) . Did you complete the replacement? | Go to Step 8 | |
| 7 | Replace the leaking fuel pipe. Refer to Fuel Hose/Pipe Replacement - Tank (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Hose/Pipe Replacement - Tank (TrailBlazer, Envoy, Rainier) . Did you complete the replacement? | Go to Step 8 | |
| 8 | Operate the system under the condition of the customer concern in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
| CAUTION |
|---|
| Gasoline or gasoline vapors are highly flammable. A fire could occur if an ignition source is present. Never drain or store gasoline or diesel fuel in an open container, due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby. |
| IMPORTANT |
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| If the floating indicator registers any flow after stabilizing, a leak is evident. |
| IMPORTANT |
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| It may be necessary to partially lower the fuel tank. Refer to Fuel Tank Replacement (TrailBlazer EXT, Envoy XL, Envoy XUV) or Fuel Tank Replacement (TrailBlazer, Envoy, Rainier) . |
Fuel Tank Leak Test
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system, and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.
Ethanol concentrations of greater than 10 percent can cause driveability conditions and fuel system deterioration. Fuel with more than 10 percent ethanol could result in driveability conditions such as hesitation, lack of power, stalling, or no start. Excessive concentrations of ethanol used in vehicles not designed for it may cause fuel system corrosion, deterioration of rubber components, and fuel filter restriction.
Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust or deterioration.
Ethanol concentrations of greater than 10 percent can cause driveability conditions and fuel system deterioration. Fuel with more than 10 percent ethanol could result in driveability conditions such as hesitation, lack of power, stalling, or no start. Excessive concentrations of ethanol used in vehicles not designed for it may cause fuel system corrosion, deterioration of rubber components, and fuel filter restriction.
The number below refers to the step number on the diagnostic table.
- 5: A few sparks, then nothing is considered no spark.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | |
| 2 | Are DTCs P0335 or P0336 set? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 | |
| 3 | Attempt to start the engine. Does the engine start and run? | Go to Step 4 | Go to Step 15 | |
| 4 | Observe the Misfire Current Counters parameter with a scan tool. Does the scan tool display any Misfire Current Counters incrementing? | Go to Step 5 | Go to Diagnostic Aids | |
| 5 | Remove the ignition coil for the affected cylinder. Refer to Ignition Coil(s) Replacement . Install J 26792 Spark Tester to the spark plug boot. See Special Tools . Attach the clamp end of J 26792 to a good engine ground. See Special Tools . Observe J 26792 . See Special Tools . Crank the engine. Does spark jump the tester gap? | Go to Step 11 | Go to Step 6 | |
| 6 | Turn OFF the ignition. Disconnect the ignition coil for the misfiring cylinder. Turn ON the ignition, with the engine OFF. Measure the battery voltage with a DMM. Connect a test lamp between the ignition 1 voltage circuit at the harness connector of the affected ignition coil and a good ground. Refer to Probing Electrical Connectors in Wiring Systems. Measure the voltage from the ignition 1 voltage circuit to a good ground with a DMM. Refer to Measuring Voltage Drop in Wiring Systems. Is the voltage within 0.50 volts of the specified value? | B+ | Go to Step 7 | Go to Step 15 |
| 7 | Probe the ignition 1 voltage circuit of the affected ignition coil with a test lamp connected to the ignition coil ground circuit. Does the test lamp illuminate? | Go to Step 8 | Go to Step 16 | |
| 8 | Start the engine. Measure the DC frequency from the ignition control (IC) control circuit of the respective ignition coil to a good ground. Does the frequency measure within the specified range? | 2-20 Hz | Go to Step 14 | Go to Step 9 |
| 9 | Turn ON the ignition, with engine OFF. Measure the voltage from the IC circuit of the respective ignition coil to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems. Does the voltage measure greater than the specified value? | 1 V | Go to Step 17 | Go to Step 10 |
| 10 | Test the IC circuit for the following conditions: An open A short to ground High resistance Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 13 | |
| 11 | Exchange the spark plug with a spark plug from a non-misfiring cylinder. Refer to Spark Plug Replacement . Install the ignition coil. Start the engine. Does the scan tool display that the misfire followed that spark plug? | Go to Step 20 | Go to Step 12 | |
| 12 | Inspect the insulating spark plug boot and conducting spring for the following conditions: Any contamination Any deterioration Any arching Did you find and correct the condition? | Go to Step 21 | Go to Symptoms - Engine Mechanical in Engine Mechanical | |
| 13 | Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 19 | |
| 14 | Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 18 | |
| 15 | Repair the open, high resistance, or short to ground in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 21 | ||
| 16 | Repair the open in the ignition coil ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 21 | ||
| 17 | Repair the short to voltage in the IC circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 21 | ||
| 18 | Replace the ignition coil. Refer to Ignition Coil(s) Replacement . Did you complete the replacement? | Go to Step 21 | ||
| 19 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 21 | ||
| 20 | Replace the spark plug. Refer to Spark Plug Replacement . Did you complete the replacement? | Go to Step 21 | ||
| 21 | Attempt to start the engine. Does the engine start and run? | Go to Step 22 | Go to Step 2 | |
| 22 | Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Let the engine reach operating temperature. Have any other DTCs not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | |
Electronic Ignition (EI) System Diagnosis
Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the inspection/maintenance (I/M) emission inspection in order to renew license plates. This is accomplished by viewing the I/M System Status display on a scan tool. Using a scan tool, the technician can observe the I/M System Status in order to verify that the vehicle meets the criteria that complies with the local area requirements.
The purpose of the Inspection/Maintenance (I/M) Complete System Set Procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics, and complete the trips for those particular diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES.
The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the secondary air injection (AIR) system. The test may be used to set the I/M System Status to YES.
The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the catalyst system. The test may be used to set the I/M System Status indicators to YES.
The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the evaporative emission (EVAP) system. The test may be used to set the I/M System Status indicators to YES. Service Bay Tests are included on the scan tool for some systems depending upon vehicle make and model. The test is designed to allow the EVAP Diagnostic Tests to run in service bay conditions.
The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the oxygen sensor (O2S, HO2S) system. The test may be used to set the I/M System Status to YES.
The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the heated oxygen sensor (HO2S) system. The test may be used to set the I/M System Status to YES.