Diagnostic Aids

An intermittent can be caused by a poor connection, rubbed-through wire insulation or a wire broken inside insulation. Check for backed out PCM terminals GC4 or GC3, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and a damaged harness. If connections and harness are okay, connect a DVOM between affected terminal and ground. Move related wiring and connectors. If a failure is induced, voltage reading will change. Check for a mis-scaled coolant temperature sensor. See Code 15 chart in appropriate TESTS W/CODES article in this section. Also check for a basic cooling system problem.

Fig 1: Chart C-12A Schematic (3.8L "E" Body) Cooling Fan Circuit Diagnosis

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart C-12A Flow Chart (1 Of 5)(3.8L "E" Body) Cooling Fan Circuit Diagnosis

Courtesy of GENERAL MOTORS CORP.