Lucerne V6-3.8L (2007)
Malfunction Indicator Lamp: Testing and Inspection
Malfunction Indicator Lamp (MIL) Diagnosis
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection/Initial Inspection and
Diagnostic Overview/Diagnostic Starting Point - Vehicle
* Strategy Based Diagnosis
* Diagnostic Procedure Instructions
Circuit/System Description
Ignition voltage is supplied to the malfunction indicator lamp (MIL). The powertrain control module (PCM) turns the MIL ON by grounding the MIL
control circuit.
Circuit/System Verification
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 cluster.
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 instrument cluster.
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 PCM.
‹› 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
PCM.
5. If all circuits test normal, replace the instrument cluster.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Control Module References for PCM replacement, setup and programming
* Instrument Cluster Replacement. See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Diagnostic Trouble Code
Tests and Associated Procedures/Verification Tests and Procedures See: Testing and Inspection/Programming and Relearning
