• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
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.
The MIL should turn ON and OFF when commanded with a scan tool.
⇒ | 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. |
⇒ | 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. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for ECM and IPC replacement, setup, and programming