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.

### DTC Descriptor

DTC P0650: Malfunction Indicator Lamp (MIL) Control Circuit

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage
--- | --- | --- | ---
MIL Voltage Supply | P0650 | P0650 | --
MIL Control | P0650 | P0650 | P0650

### 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 control module monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL.

### Conditions for Running the DTC

• | Ignition ON.

• | System voltage is 9-18 volts.

• | DTC P0650 runs continuously when the ignition is ON.

### Conditions for Setting the DTC

The control module detects that the commanded state of the MIL driver and the actual state of the control circuit do not match, and this occurs 20 times of the 25 test samples.

### Action Taken When the DTC Sets

DTC P0650 is a type B DTC.

### Conditions for Clearing the DTC

DTC P0650 is a type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Controls Connector End Views

• | Engine Control Module Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Engine Control Module Scan Tool Information

### Circuit/System Verification

1. Ignition ON, the MIL should turn ON and OFF when commanded with a scan tool.
2. Ignition ON, observe the scan tool MIL Circuit Status parameter. The reading should indicate Incomplete and continue to indicate Incomplete when commanding the MIL ON and OFF.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness at the Instrument Panel Cluster (IPC).
2. Ignition ON, verify that the test lamp illuminates between the ignition circuit and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for short or open to ground, or high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the IPC.

3. Connect a test lamp between the control circuit and the ignition circuit.
4. Command the MIL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒ | If the test lamp remains illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the engine control module (ECM).

⇒ | If test lamp remains OFF, test the control circuit for a short to voltage, or an open or high resistance. If the circuit test normal, replace the ECM.

⇒ | If all circuits test normal, replace the IPC.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to Control Module References for ECM and instrument panel cluster replacement, setup, and programming.