Diagnostic Instructions

DTC Descriptor

DTC P0655: Engine Coolant Temperature Lamp Control Circuit

DTC P0655 01: Engine Coolant Temperature Lamp Control Circuit Short to Battery

DTC P0655 02: Engine Coolant Temperature Lamp Control Circuit Short to Ground

DTC P0655 04: Engine Coolant Temperature Lamp Control Circuit Open Circuit

DTC P0655 54: Engine Coolant Temperature Lamp Control Circuit Temperature High

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Voltage Supply	P0655, P0655 02	P0655, P0655 04	--	--
Control Circuit	P0655, P0655 02	P0655, P0655 04	P0655, P0655 01	P0655 54

Circuit/System Description

The engine coolant temperature lamp is located on the instrument panel cluster (IPC). The lamp informs the driver if an engine over heat condition has occurred and that the engine cooling system requires service. The engine control module (ECM) monitors the lamp control circuit for conditions that are incorrect for the commanded state of the lamp. For example, a failure condition exists if the ECM detects low voltage when the lamp is commanded OFF, or high voltage when the lamp is commanded ON.

Conditions for Running the DTC

Conditions for Setting the DTC

P0655 01

The ECM detects a short to voltage on the circuit that controls the lamp.

P0655 02

The ECM detects a short to ground on the circuit that controls the lamp.

P0655 04

The ECM detects an open on the circuit that controls the lamp.

P0655 54

The ECM detects that the internal output driver is over temperature.

Action Taken When the DTC Sets

DTC P0655 is a Type C DTC.

Conditions for Clearing the DTC

DTC P0655 is a Type C DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Circuit/System Verification

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

Circuit/System Testing

1. If any other IPC indicators or gages are inoperative, refer to Symptoms - Instrument Panel, Gages and Console .
2. Ignition OFF, disconnect the ECM harness connectors. Ignition ON, the lamp should not illuminate.

⇒	If the lamp is illuminated, test the lamp control circuit for a short to ground. If the circuit tests normal, replace the IPC.

3. Ignition ON, connect a 3A fused jumper wire between the lamp control circuit and ground. The lamp should illuminate.

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

4. If all circuits/connections test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.