Diagnostic Aids

If an overheating condition is suspected, verify if this is due to actual boilover. If gauge or light indicates an overheat condition, and no boilover is in evidence, inspect the gauge/light circuit for malfunction.

If vehicle is overheating and the gauge or light indicates the same, 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 Flow Chart (1 of 2) ("U" Body)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Cooling Fan Flow Chart (2 of 2) ("U" Body)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Cooling Fan Circuit Diagram ("U" Body)

Courtesy of GENERAL MOTORS CORP.