A - E Charts & Related Test Procedures

Engine Temperature Warning Light Circuit Diagram:

CIRCUIT DESCRIPTION:

The TEMP light gets power through the gauges fuse whenever the ignition is turned "ON" . The ECM "lites" the bulb by completing the circuit to ground when the engine temperature is above 124°C (255°F).

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

NOTE: Before attempting to diagnose a "TEMP" light circuit problem if the light is coming on, make sure the engine is not overheating.

Chart C-16, PCM Control Engine Temperature Warning Light Diagnosis:

1. With the ignition "ON" and engine "OFF," the PCM should complete the circuit and the test light (and "HOT" light) should be "ON".
2. The TEMP light should only be "ON" while the ignition is on and the engine is stopped, or when the engine is running and the coolant temperature is above 124°C (255°F).

DIAGNOSTIC AIDS

The coolant temperature sensor in rare cases, may fail to indicate the correct engine coolant temperature without setting a trouble code. This could result in turning "ON" the "TEMP" light without having an overheating condition. It could also result in overheating without the "TEMP" light being turned "ON." See coolant sensor temperature vs resistance values on trouble Code diagnostic chart Code 15. Compare coolant temperature reading from scanner to this chart. Replace coolant temperature sensor if mis-scaled.