For 1990-2009 cars

### Diagnostic Instructions

• | 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.

### Circuit/System Description

The malfunction indicator lamp (MIL) is located on the instrument panel. Ignition 1 voltage is supplied directly to the 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.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, command the Malfunction Indicator Lamp (MIL) ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. If any other IPC indicators or gages are inoperative, refer to Instrument Cluster Gages Inoperative.
2. Ignition OFF, disconnect the K20 ECM harness connector X2.
3. Ignition ON, the MIL should not illuminate.

⇒ | If the MIL illuminates, test the MIL control circuit terminal 12 X2 for a short to ground. If the circuit test normal, replace the IPC.

4. Connect a 3 A fused jumper wire between the MIL control circuit terminal 12 X2 and ground. The MIL should illuminate.

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

5. If all circuits test normal, replace the K20 ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Instrument Cluster Replacement

• | Control Module References for ECM replacement, setup, and programming