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.