Malfunction Indicator Lamp (MIL) Always On

Malfunction Indicator Lamp (MIL) Always On

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

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 driver information center (DIC)/clock.

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 ([1][2]Electrical Diagrams)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Testing

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

* MR 140 controller terminal K64
* MT 34 controller terminal C49

2. Ignition ON, observe the MIL.

• If the MIL is illuminated, test the MIL control circuit for a short to ground. If the circuit tests normal, replace the driver information center (DIC)/clock.

• If the MIL is not illuminated, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Clock Replacement (Hatchback) (Clock Replacement (Hatchback))Clock Replacement (Notchback) (Clock Replacement (Notchback))
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming