Diagnostic Aids

An intermittent problem may be caused by a poor connection, rubbed - through wire insulation or a wire broken inside the insulation. Check for the following items:

• Poor connection or damaged harness - Inspect the ECM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.
• Faulty engine coolant temperature sensor - Using a Tech 2, compare engine coolant temperature with intake air temperature on a completely cool engine. Engine coolant temperature should be within 10 °C of intake air temperature. If not, replace the ECT sensor.