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 ECM.
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: Instrument Cluster Schematics or Engine Controls Schematics Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views or Engine Control Module (ECM) Connector End Views | ||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 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. Disconnect the ECM. Turn ON the ignition with the engine OFF. Connect a 3-amp fused jumper wire between the MIL control circuit in the ECM harness connector and a good ground. Is the MIL illuminated? | Go to Step 9 | Go to Step 5 | |
| 5 | Turn OFF the ignition. Remove the instrument panel cluster (IPC). Refer to Instrument Panel Cluster (IPC) Replacement. Turn ON the ignition. 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 6 | Go to Step 11 | |
| 6 | Test the MIL control circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 14 | Go to Step 7 | |
| 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 14 | 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. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 | |
| 9 | Test for an intermittent and for a poor connection at the ECM. Refer to Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 | |
| 10 | Repair the short to ground in the ignition voltage circuit. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 14 | ||
| 11 | Repair the open in the ignition voltage circuit. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 14 | ||
| 12 | Replace the IPC. Refer to Instrument Panel Cluster (IPC) Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | Go to Step 14 | ||
| 13 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 14 | ||
| 14 | Command the MIL ON and OFF with the scan tool. Does the MIL turn ON and OFF when commanded with a scan tool? | Go to Step 15 | Go to Step 2 | |
| 15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK | |
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 ECM.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Instrument Cluster Schematics in Instrument Panel, Gages, and Console or Engine Controls Schematics Connector End View Reference: Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console or Engine Control Module (ECM) 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 engine control module (ECM). Refer to Control Module References in Computer/Integrating Systems. 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 ECM. 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 System Check - 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 to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met
- The battery is completely charged. Refer to «Battery Inspection/Test»(ref-201045-S17804928652005102400000).
- The engine cranking speed is acceptable. Refer to «Engine Cranks Slowly»(ref-201045-S30318518612005102400000).
- There is adequate fuel in the fuel tank.
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) 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 | |
| 2 | Turn ON the ignition, with the engine OFF. Observe the DTC information with a scan tool. Does the scan tool display DTCs P0101, P0108, P0230, P0335, P0336, P0601, P0602, P0604, P0606, P0607, P0641, P0651, P0685, P0689, P0690, P1621, P1630, P1631, P1682, or P2610? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 3 | |
| 3 | Does the scan tool display any body control module (BCM) or vehicle theft deterrent (VTD) DTCs? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 4 | |
| 4 | Turn ON the ignition, with the engine OFF. Probe both sides of the fuses located in the underhood electrical center listed below using a test lamp connected to ground. The auto trans fuse The engine sensor fuse The INJ/IGN fuse, even bank The INJ/IGN fuse, odd bank Does the test lamp illuminate on at least one side of each fuse? | Go to Step 5 | Go to DTC P0685, P0689, or P0690 | |
| 5 | Command the fuel pump ON with a scan tool. Does the fuel pump operate? | Go to Step 6 | Go to Fuel Pump Electrical Circuit Diagnosis | |
| 6 | Turn OFF the ignition. Disconnect a spark plug wire. Install J 26792 Spark Tester. See Special Tools. Attempt to start the engine. Does the spark tester spark? | Go to Step 7 | Go to Electronic Ignition (EI) System Diagnosis | |
| 7 | Turn OFF the ignition. Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal. IMPORTANT: You may need to command the fuel pump ON a few times to obtain the highest possible fuel pressure. Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. Observe the fuel pressure while the fuel pump is operating. Is the fuel pressure within the specified range? | 379-427 kPa (55-62 psi) | Go to Step 8 | Go to Fuel System Diagnosis |
| 8 | Inspect for the following conditions: Collapsed air intake duct Restricted air filter element - Refer to Air Cleaner Element Replacement. Spark plugs for being fouled - Refer to Spark Plug Inspection. If the spark plugs are fouled, determine what caused the condition. Engine mechanical condition, for example, broken timing chain, low compression - Refer to Engine Compression Test. Restricted exhaust system - Refer to Restricted Exhaust. An engine coolant temperature (ECT) sensor that has shifted in value - Refer to Temperature vs Resistance. Compare the MAP parameter to another vehicle. The parameters should be close in value. Refer to DTC P0106. Did you complete the action? | Go to Step 9 | Go to Hard Start | |
| 9 | Clear the DTCs with a scan tool. Attempt to start the engine. Does the engine start and continue to operate? | Go to Step 10 | Go to Step 2 | |
| 10 | Idle the engine. Allow the engine to reach operating temperature. Observe the DTC information with a scan tool. Are any DTCs displayed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK | |
| IMPORTANT |
|---|
| You may need to command the fuel pump ON a few times to obtain the highest possible fuel pressure. |
Engine Cranks but Does Not Run
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step determines if the condition is located on the coil side or on the switch side of the fuel pump relay.
- 3: This step verifies that the engine control module (ECM) is providing voltage to the fuel pump relay.
- 4: This step tests for an open in the ground circuit to the fuel pump relay.
- 5: This step determines if a voltage is constantly being applied to the fuel pump relay.
- 12: This step determines if the condition with the circuit is intermittent.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) 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 |
| 2 | Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON and OFF with a scan tool. Does the fuel pump turn ON and OFF when commanded with a scan tool? | Go to Step 9 | Go to Step 3 |
| 3 | Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Probe the control circuit of the fuel pump relay with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors. Command the fuel pump relay ON and OFF with a scan tool. Does the test lamp turn ON and OFF when commanded with a scan tool? | Go to Step 4 | Go to Step 5 |
| 4 | 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. Does the test lamp turn ON and OFF when commanded with a scan tool? | Go to Step 18 | Go to Step 21 |
| 5 | Does the test lamp remain illuminated? | Go to Step 6 | Go to Step 7 |
| 6 | Test the control circuit of the fuel pump relay for a short to voltage. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 26 |
| 7 | Test the control circuit of the fuel pump relay for a short to ground or for an open. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 19 |
| 8 | Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously? | Go to Step 9 | Go to Step 10 |
| 9 | Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously? | Go to Step 20 | Go to Step 25 |
| 10 | Inspect the fuel pump fuse. Is the fuel pump fuse open? | Go to Step 11 | Go to Step 13 |
| 11 | Test the supply voltage circuit of the fuel pump, between the fuel pump fuse and the fuel pump for a short to ground. Refer to Circuit Testing and Wiring Repairs. Replace the fuel pump fuse if necessary. Did you find and correct the condition? | Go to Step 27 | Go to Step 12 |
| 12 | Install all removed electrical components. Install a new fuel pump fuse. Command the fuel pump relay ON with a scan tool. Inspect the fuel pump fuse. Is the fuel pump fuse open? | Go to Step 23 | Go to Intermittent Conditions |
| 13 | Turn OFF the ignition. Remove the fuel pump relay. Turn ON the ignition, with the engine OFF. Probe the battery voltage circuit of the fuel pump relay switch with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 14 | Go to Step 22 |
| 14 | Connect a 20-amp fused jumper wire between the battery voltage circuit of the fuel pump relay switch and the supply voltage circuit of the fuel pump. Does the fuel pump operate? | Go to Step 18 | Go to Step 15 |
| 15 | Test the supply voltage circuit of the fuel pump, between the fuel pump relay and the fuel pump for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 16 |
| 16 | IMPORTANT: Inspect the ground circuit for being tight, corrosion on terminals, or damage to the wiring harness. Test the ground circuit of the fuel pump for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs.Did you find and correct the condition? | Go to Step 27 | Go to Step 17 |
| 17 | Test for an intermittent or for a poor connection at the fuel pump sender assembly connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 23 |
| 18 | Test for an intermittent or for a poor connection at the fuel pump relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 25 |
| 19 | Test for an intermittent and for a poor connection at the harness connector of the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 27 | Go to Step 26 |
| 20 | Repair the short to voltage in the supply voltage circuit of the fuel pump. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 27 | |
| 21 | Repair the open in the fuel pump relay ground circuit. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 27 | |
| 22 | Repair the open in the battery voltage circuit of the fuel pump relay. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 27 | |
| 23 | Test for an intermittent and for a poor connection at the fuel pump sender assembly connector within the fuel tank. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the conditions? | Go to Step 27 | Go to Step 24 |
| 24 | Replace the fuel pump sender assembly. Refer to Fuel Sender Assembly Replacement. Replace the fuel pump fuse if necessary. Did you complete the replacement? | Go to Step 27 | |
| 25 | Replace the fuel pump relay. Did you complete the replacement? | Go to Step 27 | |
| 26 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 27 | |
| 27 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
| IMPORTANT |
|---|
| Inspect the ground circuit for being tight, corrosion on terminals, or damage to the wiring harness. |
Fuel Pump Electrical Circuit Diagnosis
System Description
The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.
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.
The fuel tank stores the fuel supply. 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 pump also supplies fuel to a venturi pump located on the bottom of the fuel sender assembly. The function of the venturi pump is to fill the fuel sender assembly reservoir. 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 |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics or 6.0L VIN U J 41415-40 Connector End View Reference: 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 | IMPORTANT: Inspect the fuel system for 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. CAUTION: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete. 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? | 385-425 kPa (55-62 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 one 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. Does 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 chassis fuel hose from the engine compartment fuel pipe. Refer to Quick Connect Fitting(s) Service (Metal Collar). Install the J 37287 Fuel Line Shut-off Adapter between the chassis fuel hose and the engine compartment fuel 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 one 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? | 427 kPa (62 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 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 lines 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. Replace any leaking fuel injectors. 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 external leaks before proceeding with this diagnostic. |
| IMPORTANT |
|---|
| Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. |
| CAUTION |
|---|
| Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete. |
| 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. 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 | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) |
| 2nd Reading | 215 kPa (31 psi) | 201 kPa (29 psi) | 208 kPa (30 psi) | 229 kPa (33 psi) |
| Amount of Drop | 165 kPa (24 psi) | 179 kPa (26 psi) | 172 kPa (25 psi) | 151 kPa (22 psi) |
| Average Range: 156-176 kPa (22.5-25.5 psi) | Injector OK | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop |
Fuel Injector Balance Test Example (Typical)
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 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 ECT is above 94°C (201°F). IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. 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. 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? | 380-427 kPa (55-62 psi) | Go to Step 4 | Go to Fuel System Diagnosis |
| 4 | IMPORTANT: The fuel pressure will decrease 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 5 minutes.Does the fuel pressure decrease to less than the specified value? | 350 kPa (51 psi) | Go to Fuel System Diagnosis | Go to Step 5 |
| 5 | NOTE: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding. Connect the J 39021 Fuel Injector Tester to a fuel injector using the. See Special Tools. J 44602 Injector Test Adapter. See Special Tools. 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 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: 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 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 fuel pressure reading. Repeat steps 1 through 6 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 6 | Go to Symptoms - Engine Controls |
| 6 | Replace the affected fuel injector. Refer to Fuel Injector Replacement. Did you complete the replacement? | Go to Step 7 | ||
| 7 | 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 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. |
| IMPORTANT |
|---|
| The fuel pressure will decrease 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 |
|---|
| 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 Special Tool
The scan tool is first used to energize the fuel pump. 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 the flow through each injector.
| Cylinder | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| 1st Reading | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) | 380 kPa (55 psi) |
| 2nd Reading | 215 kPa (31 psi) | 201 kPa (29 psi) | 208 kPa (30 psi) | 229 kPa (33 psi) |
| Amount of Drop | 165 kPa (24 psi) | 179 kPa (26 psi) | 172 kPa (25 psi) | 151 kPa (22 psi) |
| Average Range: 156-176 kPa (22.5-25.5 psi) | Injector OK | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop |
Fuel Injector Balance Test Example (Typical)
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle | |
| 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 ECT is above 94°C (201°F). IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. 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. 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? | 380-427 kPa (55-62 psi) | Go to Step 4 | Go to Fuel System Diagnosis |
| 4 | IMPORTANT: The fuel pressure will decrease 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 5 minutes.Does the fuel pressure decrease to less than the specified value? | 350 kPa (51 psi) | Go to Fuel System Diagnosis | Go to Step 5 |
| 5 | NOTE: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding. Select the Fuel Injector Balance Test function with a scan tool. 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 6 | Go to Symptoms - Engine Controls |
| 6 | Replace the affected fuel injector. Refer to Fuel Injector Replacement. Did you complete the replacement? | Go to Step 7 | ||
| 7 | 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 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. |
| IMPORTANT |
|---|
| The fuel pressure will decrease 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 |
|---|
| 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 when the evaporative emission (EVAP) diagnostics complete one test cycle. The malfunction indicator lamp (MIL) will illuminate after the EVAP diagnostics have failed two 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 |
| 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. Inspect the fuel tank and 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 the J 41413-200 Evaporative Emissions System Tester (EEST) and the J 41415-40 Fuel Tank Cap Adaptor or the GE-41415-50 Interrupted Thread Fuel Tank Cap Adapter. See Special Tools. IMPORTANT: If the floating indicator registers any flow after stabilizing, a leak is evident. Test for a fuel tank leak referring to the J 41413-210 Operation Manual. Raise the vehicle. Refer to Lifting and Jacking the Vehicle. 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 Operation Manual, 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. Inspect for leaks in any of the following locations: The fuel tank, fill limiter vent valve, the pressure relief valve, and the grade vent valves - Refer to Fuel Tank Replacement. The fuel sender housing and the 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 vapor pipes - Refer to Evaporative Emission (EVAP) Hoses/Pipes Replacement - Engine. The fuel fill pipe and hose - Refer to Filler Tube Replacement. 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. Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the leaking fuel pipe. Refer to Fuel Hose/Pipes Replacement - Chassis. Did you complete the replacement? | Go to Step 8 | |
| 8 | Operate the system 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 |
|---|
| If the floating indicator registers any flow after stabilizing, a leak is evident. |
| IMPORTANT |
|---|
| It may be necessary to partially lower the fuel tank. Refer to Fuel Tank Replacement. |
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.
Alcohol concentrations of 10 percent or greater in fuel can be detrimental to fuel system components. Alcohol contamination may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack or power, stalling, or no start.
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 numbers below refer to the step numbers on the diagnostic table.
- 5: Monitoring the misfire current counters determines if a fault is present.
- 12: A good indication that the fuse is open is all off the misfire current counters are incrementing on one side of the engine. Inspect the ignition positive voltage circuit for a grounded circuit. If the fuse is open and the ignition coil circuits are OK, inspect the injector circuits for being grounded.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) 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 | |
| 2 | Attempt to start the engine. Does the engine start and run? | Go to Step 5 | Go to Step 3 | |
| 3 | Observe the Engine Speed parameter with a scan tool. Crank the engine. Does the scan tool indicate RPM is present? | Go to Step 7 | Go to Step 4 | |
| 4 | Is DTC P0335, P0336, or P0351-P0358 also set? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 16 | |
| 5 | Idle the engine. Observe the misfire current counters on the scan tool. Does the scan tool display any misfire current counters incrementing? | Go to Step 6 | Go to Diagnostic Aids | |
| 6 | Do the misfire current counters increment for most cylinders on one bank of the engine? | Go to Step 12 | Go to Step 7 | |
| 7 | Inspect the spark plug wire for open circuits, cracks, or improper seating of terminals at the spark plug or coil before proceeding with test. Refer to Spark Plug Wire Inspection. Inspect for spark at the plug with the J 26792 Spark Tester or equivalent while cranking. See Special Tools. A few sparks, then nothing is considered no spark. Is adequate spark present? | Go to Step 33 | Go to Step 8 | |
| 8 | Measure the spark plug wire resistance. Refer to Spark Plug Wire Inspection. Does the resistance measure within the specified range? | 188-312 ohms | Go to Step 32 | Go to Step 9 |
| 9 | Turn OFF the ignition. Disconnect the inoperative ignition coil. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage circuit of the ignition coil with a test lamp connected to a good ground. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 10 | Go to Step 13 | |
| 10 | Probe the ignition 1 voltage circuit at the ignition coil with a test lamp connected to the ground circuit of the ignition coil. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 11 | Go to Step 14 | |
| 11 | Probe the ignition 1 voltage circuit at the ignition coil with a test lamp connected to the low reference circuit of the ignition coil. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 20 | Go to Step 15 | |
| 12 | Inspect for an open even INJ/IGN fuse or odd INJ/IGN fuse. Is the fuse open? | Go to Step 29 | Go to Step 23 | |
| 13 | Disconnect the main ignition coil 8-way connector. Probe the ignition 1 voltage circuit at the ignition coil main 8-way connector using the test lamp connected to battery ground. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 24 | Go to Step 23 | |
| 14 | Disconnect the main ignition coil 8-way connector. Probe the ignition 1 voltage circuit on the harness side with a test lamp connected to the ground circuit of the ignition coil. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 18 | Go to Step 26 | |
| 15 | Disconnect the main ignition coil 8-way connector. Probe the ignition 1 voltage circuit on the harness side with a test lamp connected to the low reference circuit of the ignition coil. Refer to Probing Electrical Connectors. Does the test lamp illuminate? | Go to Step 19 | Go to Step 28 | |
| 16 | Turn ON the ignition, with the engine OFF. Disconnect the crankshaft position (CKP) sensor. Measure the voltage from the CKP sensor 12-volt reference circuit and a good ground with the DMM. Compare the measured voltage with the system voltage. Is the difference in the voltage more than the specified value? | 0.5 V | Go to Step 17 | Go to Step 30 |
| 17 | Test for a short to ground in the CKP 12-volt reference circuit or the camshaft position (CMP) sensor 12-volt reference circuit. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | Go to Step 35 | Go to Step 22 | |
| 18 | Test for an intermittent and for a poor connection at the ignition coil 8-way connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 35 | Go to Step 25 | |
| 19 | Test for an intermittent and for a poor connection at the ignition coil 8-way connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 35 | Go to Step 27 | |
| 20 | 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. Did you find and correct the condition? | Go to Step 35 | Go to Step 31 | |
| 21 | Test for an intermittent and for a poor connection at the CKP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 35 | Go to Step 30 | |
| 22 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | Go to Step 35 | Go to Step 34 | |
| 23 | Repair the open or high resistance in the ignition 1 voltage circuit between the fuse block and the splice. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 24 | Repair the open or high resistance in the ignition 1 voltage circuit between the splice and the ignition coil connector. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 25 | Repair the open in the ground circuit between the main 8-way connector and the ignition coil. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 26 | Repair the open in the ground circuit. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 27 | Repair the open in the low reference circuit between the main 8-way connector and the ignition coil. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 28 | Repair the open in the low reference circuit between the ECM and the splice. Refer to Wiring Repairs. Did you complete the repair? | Go to Step 35 | ||
| 29 | Repair the ignition 1 voltage for a short to ground. Refer to Wiring Repairs. Replace the fuse. Did you complete the repair? | Go to Step 35 | ||
| 30 | Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement. Did you complete the replacement? | Go to Step 35 | ||
| 31 | Replace the ignition coil. Refer to Ignition Coil(s) Replacement. Did you complete the replacement? | Go to Step 35 | ||
| 32 | Replace the spark plug wire. Refer to Spark Plug Wire Replacement. Did you complete the replacement? | Go to Step 35 | ||
| 33 | Replace the spark plug. Refer to Spark Plug Replacement. Did you complete the replacement? | Go to Step 35 | ||
| 34 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 35 | ||
| 35 | Attempt to start the engine. Does the engine start and continue to run? | Go to Step 36 | Go to Step 3 | |
| 36 | Clear the DTCs with a scan tool. Turn OFF the engine for 30 seconds. Start the engine. Allow the engine to reach operating temperature. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | 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 comply 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 to complete the trips for those particular diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform this test when more than one or all of the I/M System Status indicators are set to NO.
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step is to run the HO2S heater tests and initiate the EVAP System Test. Preprogramming the scan tool will reduce the amount of time the oxygen sensor heaters operate while verifying the enable criteria.
- 3: This step is to run the EVAP, the AIR, and the oxygen sensor tests. The EVAP test begins once the engine coolant reaches a calibrated temperature. The AIR test, if equipped, begins shortly after Closed Loop and the indicated speed is achieved. The oxygen sensor tests begin once the engine is at operating temperature, in Closed Loop fuel control, and a calibrated amount of time has elapsed.
- 4: This step is to run the Catalyst Tests. This test runs during the idle period immediately following a cruise period that meets a minimum calibrated RPM and time period.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| CAUTION: Refer to Road Test Caution in Cautions and Notices. | ||||
| 1 | Did you perform the Inspection/Maintenance (I/M) System Check? | Go to Step 2 | Go to Inspection/Maintenance (I/M) System Check | |
| 2 | IMPORTANT: Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes in order to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure. Preprogram the scan tool with the vehicle information before the ignition is turned ON. Ensure that the vehicle is within the Conditions for Running specified in the supporting text. Turn OFF all of the accessories, including the A/C, and blower fan. Set the vehicle parking brake. Verify the transmission is in Park for automatic transmissions and Neutral for manual transmissions. Start the engine and allow it to idle for the specified time. Is the action complete? | 2 minutes | Go to Step 3 | |
| 3 | In order for the next group of tests to run, the vehicle must operate in the following conditions: Acceleration at part throttle to 90 km/h (55 mph), with this speed maintained until the engine reaches operating temperature. This may be up to 10 minutes depending on the start up coolant temperature. Continue operation under these conditions for an additional 6 minutes. Is the action complete? | Go to Step 4 | ||
| 4 | In order for the next group of tests to run, the vehicle must operate in the following conditions: Acceleration at part throttle to 75-89 km/h (45-55 mph) with this speed maintained for 2 minutes. Brake safely to a stop. Engine idling for 2 minutes while the following criteria are maintained: Service brake depressed Automatic transmission in drive Manual transmission in neutral with the clutch pedal depressed Is the action complete? | Go to Step 5 | ||
| 5 | Observe the I/M System Status display with a scan tool. Did all of the I/M System Status indicators update to YES? | Go to Step 6 | Go to the I/M System Set Procedure for the systems that have not updated | |
| 6 | Observe the emission related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any emission related DTCs set? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | |
| CAUTION |
|---|
| Refer to Road Test Caution in Cautions and Notices. |
| IMPORTANT |
|---|
| Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes in order to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure. |
Inspection/Maintenance (I/M) Complete System Set Procedure
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 I/M System Status display on the scan tool provides an indication of whether the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made even if all of the other tests for that system have not run.
This test satisfies 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. Ensure that the vehicle meets the requirements listed in Conditions for Running before performing either EVAP system test. Failure to meet the necessary requirements may produce inaccurate test results.
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 I/M System Status display on the scan tool provides an indication of whether the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the other tests for that system have not run.
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. The I/M System Status display on the scan tool provides an indication of whether the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed, the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the other tests for that system have not run.
The purpose of the evaporative emission (EVAP) Service Bay Test is to aid in resetting the EVAP Inspection/Maintenance (I/M) System Status to complete. The EVAP Service Bay Test changes the enable criteria so that the EVAP diagnosis tests can run while in the service environment. When the tests are run the Service Bay Test will indicate a pass or will indicate a specific DTC code has failed.
Engine Control Module (ECM) Description
The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The engine control module (ECM) is the control center of this system. The ECM monitors numerous engine and vehicle functions. The ECM constantly monitors at the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The ECM also performs the diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via the malfunction indicator lamp (MIL). When the ECM detects a malfunction, the ECM stores a diagnostic trouble code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the ECM.
Malfunction Indicator Lamp (MIL) Operation
The Malfunction Indicator Lamp (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or one of the following symbols when commanded ON
Scheme 1
Scheme 2
The MIL indicates that an emissions related fault has occurred and vehicle service is required.
The following is a list of the modes of operation for the MIL
- The MIL illuminates when the ignition is turned ON, with the engine OFF. This is a bulb test to ensure the MIL is able to illuminate.
- The MIL turns OFF after the engine is started if a diagnostic fault is not present.
- The MIL remains illuminated after the engine is started if the control module detects a fault. A diagnostic trouble code (DTC) is stored any time the control module illuminates the MIL due to an emissions related fault. The MIL turns OFF after three consecutive ignition cycles in which a Test Passed has been reported for the diagnostic test that originally caused the MIL to illuminate.
- The MIL flashes if the control module detects a misfire condition which could damage the catalytic converter.
- When the MIL is illuminated and the engine stalls, the MIL will remain illuminated as long as the ignition is ON.
- When the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition is cycled OFF and then ON.
System Overview
The fuel tank stores the fuel supply. An electric fuel pump, located in the fuel tank with the fuel sender assembly, pumps the fuel to the fuel rail assembly. The pump provides the fuel at a pressure greater than is needed by the injectors. The fuel pressure regulator, part of the fuel sender assembly, keeps the fuel available to the injectors at a regulated pressure. The fuel system is returnless.
Scheme 3
The 70-litre (18.5 gallons) fuel tank is a pressed steel construction. A two piece high density polyethylene shell (1, 3) encapsulates the fuel tank (2). The fuel tank is fitted immediately behind the rear seat and is accessed through the trunk. The fuel tank is held in place by two mounting straps and the fuel filler neck is attached to the vehicle body at the fuel filler opening, located in the rear right-hand quarter panel, with three fastening nuts. The fuel tank itself is not repairable and if damaged must be replaced.
Modes of Operation
The Engine Control Module (ECM) looks at voltages from several sensors to determine how much fuel to give the engine. The fuel is delivered under one of several conditions called modes. The ECM controls all modes.
The fuel tank stores the fuel supply. An electric fuel pump, located in the fuel tank with the fuel sender assembly, pumps the fuel through an in-line fuel filter to the fuel rail assembly. The pump provides fuel at a pressure greater than what is needed by the injectors. The fuel pressure regulator, part of the fuel sender assembly, keeps the fuel available to the injectors at a regulated pressure.
EVAP System Operation
The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid to atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid ON, open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid OFF, open, fresh air will be drawn through the solenoid and vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.
Electronic Ignition (EI) System Description
The electronic ignition (EI) system is responsible for producing and controlling a high energy secondary spark. This spark is used to ignite the compressed air/fuel mixture at precisely the correct time. This provides optimal performance, fuel economy, and control of exhaust emissions. This ignition system consists of a separate ignition coil connected to each spark plug by a short secondary wire. The driver modules within each coil assembly are commanded ON/OFF by the engine control module (ECM). The ECM primarily uses engine speed and position information from the crankshaft and camshaft position (CMP) sensors to control the sequence, dwell, and timing of the spark event. The EI system consists of the following components
There is one normal mode of operation, with the spark under engine control module (ECM) control. If the Crankshaft Position (CKP) pulses are lost the engine will not run. The loss of a Camshaft Position (CMP) signal may result in a longer crank time since the ECM cannot determine which stroke the pistons are on. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.
Sensor Description
This Knock Sensor (KS) system uses one or 2 flat response 2-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The control module receives the KS signal through a signal circuit. The KS ground is supplied by the control module through a low reference circuit.
The control module learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range. The control module uses the minimum noise level to calculate a noise channel. A normal KS signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal KS signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the control module only uses KS signal information when each cylinder is near Top Dead Center (TDC) of the firing stroke. If knock is present, the signal will range outside of the noise channel.
If the control module has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero compensation level, or no spark retard. An abnormal KS signal will stay outside of the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the control module, the KS wiring, or the KS voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.
Air Intake System Description
The primary function of the air intake system is to provide filtered air to the engine. The system uses a cleaner element mounted in a housing. The cleaner housing is remotely mounted and uses intake ducts to route the incoming air into the throttle body. The secondary function of the air intake system is to muffle air induction noise. This is achieved through the use of resonators attached to the air intake ducts. The resonators are tuned to the specific powertrain. The Mass Air Flow (MAF) sensor is used to measure the air entering the engine.
See also:
• Scan Tool Data List