Malfunction Indicator Lamp (MIL) Diagnosis

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

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) monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL. For example, a failure condition exists if the ECM detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON.

Diagnostic Aids

An intermittent or poor connection at the MIL control circuit at the inline harness connector may cause this DTC to set. Inspect the connector terminals for any condition that may result in excessive resistance. Refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.

Reference Information

Schematic Reference

* Engine Controls Schematics [1][2]Electrical Diagrams

* Instrument Cluster Schematics Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

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

1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.

2. Ignition ON, observe each of the MIL Control Circuit Test parameters listed below with a scan tool:

* The MIL CKT Short Gnd Test Status

* The MIL Ckt Open Test Status

* The MIL CKT Short Volts Test Status

Each parameter should display OK or Not Run.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the K20 ECM.

2. Ignition ON, the MIL should not illuminate.

• If the MIL is illuminated, test the MIL control circuit terminal 17-X1 for a short to ground. If the circuit tests normal, replace the IPC.

3. Connect a 3 A fused jumper wire between the MIL control circuit terminal 17-X1 and ground. The MIL should illuminate.

• If the MIL illuminates, replace the ECM.

• If the MIL does not illuminate, test the MIL control circuit for a short to voltage or an open/high resistance. If the MIL control circuit tests OK, test the cluster ignition circuit terminal 19 for a short to ground or open/high resistance. If the circuits test normal, replace the IPC/bulb.

Repair Instructions

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

* Instrument Cluster Replacement Service and Repair

* Control Module References Control Module References for ECM and ICM replacement, setup, and programming