Malfunction Indicator Lamp: Testing and Inspection

Malfunction Indicator Lamp (MIL) Diagnosis

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

Reference Information
Schematic Reference

* Instrument Cluster Schematics (Instrument Cluster Schematics)
* Engine Controls Schematics ([1][2]Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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 Verification

Note: Any MIL requesting DTCs that may be set should be diagnosed first

1. Ignition ON, the MIL should turn ON and OFF when commanded with a scan tool.
2. Ignition ON, observe each of the MIL Control Circuit Test parameters listed below with a scan tool:

* The MIL Ckt Short Volts Test Status
* The MIL Ckt Open Test Status
* The MIL Ckt Short Gnd Test Status
Each parameter should display OK or Not Run.

Circuit/System Testing

1. Ignition ON, verify that the instrument panel cluster (IPC) warning indicators are illuminated.

• If the instrument panel cluster warning indicators are not illuminated, test the instrument panel cluster 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.

2. Ignition OFF, disconnect connector X1 at the ECM.
3. Ignition ON, verify the MIL is not illuminated.

• If the MIL is illuminated, inspect the MIL control circuit, ECM terminal 12 X1,for a short to ground. If the circuit tests normal, replace the IPC.

4. Ignition ON, verify that the MIL illuminates with a 3A fused jumper wire between the MIL control circuit, ECM terminal 12 X1 and ground.

• If the MIL does not illuminate, test the MIL control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

Repair Instructions

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

* Instrument Cluster Replacement (Instrument Cluster Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming