Diagnostic Instructions
Circuit/System Description
Ignition 1 voltage is supplied directly to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. There should be a steady MIL with the ignition ON and the engine OFF.
MIL Operation
The MIL is located on the instrument panel (I/P).
MIL Function
| • | The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible. |
| • | The MIL illuminates during a bulb test and a system test. |
| • | A DTC will be stored if a MIL is requested by the diagnostic. |
MIL Illumination
| • | The MIL will illuminate with the ignition switch ON and the engine not running. |
| • | The MIL will turn OFF when the engine is started. |
| • | The MIL will remain ON if the self-diagnostic system has detected a malfunction. |
| • | The MIL may turn OFF if the malfunction is no longer present. |
| • | If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated as long as the ignition switch is ON. |
| • | If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- Turn ON the ignition. Command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF when commanded.
- If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
Circuit/System Testing
- If any other indicators are inoperative, refer to
Symptoms - Instrument Panel, Gages and Console
.
- Ignition OFF, disconnect the ECM harness connector.
- Ignition ON, connect a 3-amp fused jumper wire between the MIL control circuit and ground. The MIL should illuminate.
| ⇒ | If the MIL does not illuminate, test the MIL control circuit for a short to ground, or an open/high resistance. If the circuit test normal, replace the instrument panel cluster (IPC)/bulb. |
| ⇒ | If the fuse opens, repair the MIL control circuit for a short to voltage. |
| ⇒ | If the MIL illuminates, inspect for a poor connection or replace the control module. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
