1987 Pontiac Fiero Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Diagnostic Aids

If there is a overheating problem, it must be determined if the complaint was due to an actual boil over or if the hot light or temperature gauge indicates overheating.

If the gauge or light indicates overheating, but no boil over is detected, the gauge circuit should be checked. The gauge accuracy can also be checked by comparing the coolant sensor reading using a "SCAN" tester and comparing it's reading with the gauge reading.

If the engine is actually overheating and the gauge indicates overheating, but the cooling fan is not coming on, the coolant sensor has probably shifted out of calibration and should be replaced. If the engine is overheating and the cooling fan is on, the cooling system should be checked.

Fig 1: Flow Chart C12 (1 Of 2), Cooling Fan Control Ckt (5.0/5.7L)
G7314
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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