Diagnostic Aids

WARNING: This page is about a different car, the 2002 Isuzu Trooper. However, it is still accessible from the selected car via links, so may be relevant.

An intermittent problem can be caused by:

ECT shares a common ground with transmission fluid temperature, fuel tank pressure and MAP sensor. Id DTCs related to these sensors, check ground point.
Misrouted harness, rubbed-through wire insulation or broken wire inside insulation.
Poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. Inspect wiring harness for damage.
If no obvious problem with harness is found, use scan tool to monitor ECT parameter while moving harness connectors and wiring harness. A change in display indicates source of fault.

If DTC can not be duplicated, reviewing scan tool FAILURE RECORDS data can be useful in determining mileage and frequency of DTC occurrence.