Hot Light Or Coolant Temperature Light

NOTE: These checks assume vehicle is not overheating. Verify proper operation of cooling system prior to diagnosing hot light. The coolant temperature sensor, in rare cases, may fail to indicate the correct coolant temperature without setting a diagnostic trouble code (Code 14 or 15). This could result in turning on the hot light without having an overheating condition. It could also result in engine overheating without turning on the hot light. Check coolant sensor temperature-to-resistance values in SENSOR RANGE CHARTS article in this section.

Hot light is powered by the 10-amp INDIC or GAGES fuse. Light will turn on when ECM provides a ground for the circuit. If circuit grounds between light and ECM, light will illuminate any time the ignition is turned on.

Turn ignition on with engine off (bulb test position). If hot light illuminates, go to step 3). If hot light does not illuminate, check the following and proceed to next step:
- 10-amp INDIC or GAGES fuse.
- Faulty instrument cluster bulb.
- Open circuit between fuse and hot light.
Backprobe ECM hot light driver terminal with a test light to battery voltage. Turn ignition on. If test light does not illuminate, ECM terminal connection is bad or ECM is faulty. If test light illuminates, turn ignition off. Disconnect ECM connectors. Jumper ECM hot light driver harness terminal to ground. Turn ignition on. If hot light does not illuminate, check for open circuit between hot light and ECM. If all circuits are intact and power is available to light, instrument cluster must be replaced.
Start engine. If hot light goes off, no problem is evident. If hot light is on, turn ignition off. Disconnect ECM connector. Probe ECM hot light driver harness terminal with a test light to battery voltage. If test light is off, replace ECM. If test light is on, repair short to ground in hot light driver circuit. If no short is present, replace instrument cluster.