The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC).

The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The engine control module (ECM) performs a self test for the MIL lamp and its circuitry by commanding the MIL ON and OFF every time the engine is started. The ECM monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL.

Ignition voltage is supplied to the malfunction indicator lamp (MIL). The ECM turns the MIL ON by grounding the MIL control circuit.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

The MIL should turn ON and OFF when commanded with a scan tool.

1. Ignition OFF, disconnect the harness connector at the 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM and IPC replacement, setup, and programming