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 provide an overview of each diagnostic category.

### DTC Descriptors

DTC P1650: Malfunction Indicator Lamp (MIL) Control Circuit High Voltage
DTC P1651: Malfunction Indicator Lamp (MIL) Control Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
MIL Voltage Supply | P1651 | P1651 | -- | --
MIL Control | P1651 | P1651 | P1650 | --

### 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

• | The ignition is ON or the engine is operating.

• | The ignition 1 voltage is more than 11 volts.

• | The DTCs runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P1650

The engine control module (ECM) detects the MIL control circuit is shorted to voltage.

#### P1651

The ECM detects the MIL control circuit is open or shorted to ground.

### Action Taken When the DTC Sets

DTC P1650 and P1651 are Type B DTCs.

### Conditions for Clearing the DTC

DTC P1650 and P1651 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. Turn ON the ignition, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF when commanded.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

### Circuit/System Testing

1. If any other IPC indicators or gages are inoperative, refer to Clock Malfunction .
2. Ignition OFF, disconnect the ECM harness connector.
3. Ignition ON, connect a 3-amp fused jumper wire between the MIL control circuit and the negative terminal of the battery. The MIL should illuminate.

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

⇒ | If the MIL illuminates, inspect for a poor connection or replace the control module.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Instrument Cluster Replacement

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