Envoy 2WD V8-5.3L (2007)
Malfunction Indicator Lamp: Testing and Inspection
Malfunction Indicator Lamp (MIL) Diagnosis
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
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.
Circuit/System Verification
Ignition ON, the MIL should turn ON and OFF when commanded with a scan tool.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the instrument panel cluster (IPC).
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit and ground.
‹› If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the
ignition circuit fuse is open, replace the IPC.
3. Connect a test lamp between the control circuit and the ignition circuit.
4. Command the MIL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
‹› If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
‹› If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the
ECM.
5. If all circuits test normal, replace the IPC.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. See: Powertrain Management/Computers and Control
Systems/Testing and Inspection/Diagnostic Trouble Code Tests and Associated Procedures/Verification Tests and Procedures
* Control Module References See: Testing and Inspection/Programming and Relearning
* Instrument Cluster Replacement
