Malfunction Indicator Lamp (MIL) Diagnosis
Malfunction Indicator Lamp (MIL) Diagnosis
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provide an overview of each diagnostic category.
Circuit/System Description
Ignition voltage is supplied to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit.
Diagnostic Aids
If the condition is intermittent, move the related harnesses and connectors with the ignition ON and the engine OFF, and with the engine operating while monitoring the scan tool MIL control circuit status parameters. The MIL control circuit status parameters will change from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.
Reference Information
Schematic Reference
* Instrument Cluster Schematics Instrument Cluster Schematics
* Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Note: Any MIL requesting DTCs that may be set should be diagnosed first.
1. Ignition ON, command the malfunction indicator lamp ON and OFF with a scan tool.
2. Verify that the malfunction indicator lamp turns ON and OFF as commanded.
• If the malfunction indicator lamp does not turn ON and OFF as commanded Refer to Circuit/System Testing
• If the malfunction indicator lamp turns ON and OFF as commanded
3. Ignition ON, command the malfunction indicator lamp ON and OFF with a scan tool.
4. Verify that the control circuit status parameters listed below display OK or Not Run
1. The MIL Control Circuit Low Voltage Test Status
2. The MIL Control Circuit Open Test Status
3. The MIL Control Circuit High Voltage Test Status
• If Malfunction is displayed Refer to Circuit/System Testing
• If OK or Not Run is displayed
5. Engine running, command the malfunction indicator lamp ON and OFF with a scan tool.
6. Verify that the control circuit status parameters listed below display OK or Not Run
1. The MIL Control Circuit Low Voltage Test Status
2. The MIL Control Circuit Open Test Status
3. The MIL Control Circuit High Voltage Test Status
• If Malfunction is displayed Refer to Circuit/System Testing
• If OK or Not Run is displayed
7. All OK.
Circuit/System Testing
1. Ignition OFF.
2. Disconnect the X1 harness connector at the K20 engine control module.
3. Ignition ON, verify the malfunction indicator lamp does not illuminate.
• If the malfunction indicator lamp illuminates
1. Test for infinite resistance between the malfunction indicator lamp control circuit terminal 27 X1 and ground.
• If less than infinite resistance, repair the short to ground in the circuit.
• If resistance is infinite, replace the P16 instrument cluster.
• If the malfunction indicator lamp does not illuminate
4. Connect a 3 A fused jumper wire between the malfunction indicator lamp control circuit terminal 27 X1 and ground.
5. Verify the malfunction indicator lamp illuminates.
• If the malfunction indicator lamp does not illuminate
1. Test the malfunction indicator lamp control circuit terminal 27 X1 for a short to voltage or an open/high resistance.
• If the malfunction indicator lamp control circuit terminal 27 X1 is shorted to voltage or has an open/high resistance, repair as necessary.
• If the malfunction indicator lamp control circuit terminal 27 X1 tests normal
2. Test the instrument cluster ignition voltage circuit for a short to ground or an open/high resistance.
• If the instrument cluster ignition voltage circuit is shorted to ground or has an open/high resistance, repair as necessary.
• If the instrument cluster ignition voltage circuit tests normal, replace the P16 instrument panel cluster/bulb.
• If the malfunction indicator lamp illuminates
6. Replace the K20 engine control module.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Module References Control Module References for ECM replacement, setup, and programming
* Instrument Cluster Replacement Service and Repair