Diagnostic Aids

If cooling fans operate normally but overheat condition exists, see COOLANT TEMPERATURE-TO-RESISTANCE VALUES table in CODE 14 chart in appropriate TESTS W/CODES article in this section. Replace coolant temperature sensor if mis-scaled. If coolant temperature sensor is okay, check for basic cooling system problem.

Fig 1: Chart C-12D-A Schematic (3.8L "W" Body) Cooling Fan Circuit Diagnosis (Low Speed Fan(s) On At All Times)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart C-12D-A Flow Chart (5 Of 6)(3.8L "W" Body) Cooling Fan Circuit Diagnosis (Low Speed Fan(s) On At All Times)

Courtesy of GENERAL MOTORS CORP.