Diagnostic Aids

If an overheating condition is suspected, verify if it is due to actual boilover. If gauge or light indicates an overheat condition and boilover is not evident, inspect gauge/light circuit for malfunction.

If vehicle is overheating and gauge or light indicates so, but cooling fan is not operating and scan tester indicates normal readings, coolant temperature sensor is out of calibration and should be replaced. If engine is overheating and cooling fan is on, check cooling system.

Fig 1: Cooling Fan Circuit Schematic (3.1L)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Cooling Fan Circuit Flow Chart (3.1L) (2 Of 2)

Courtesy of GENERAL MOTORS CORP.