GM Service Manual Online
For 1990-2009 cars only
    • Inspect the IGN 1 circuit breaker.
        If the circuit breaker is not open, proceed with the diagnostic procedures.
        Complete the following steps if the circuit breaker is open:
        1. Locate the cause of the overload.
        2. Repair the cause of the overload.
        3. Replace the circuit breaker.
    • Inspect the ENG circuit breaker.
        If the circuit breaker is not open, proceed with the diagnostic procedures.
        Complete the following steps if the circuit breaker is open:
        1. Locate the cause of the overload.
        2. Repair the cause of the overload.
        3. Replace the circuit breaker.
    • Inspect the radiator shutters for binding.
    • Verify that the engine coolant temperature is below 90.6°C (195°F).
        The engine coolant temperature must be below 90.6°C (195°F) in order for the radiator shutters to close.
    • Inspect for a broken or partially broken wire inside the insulation.
        A broken wire inside the insulation may cause system malfunction.
        A broken wire inside the insulation may prove GOOD in a continuity/voltage check with a system disconnected.
        These circuits may be intermittent or resistive when loaded. Inspect the circuits by monitoring them for a voltage drop with the system operational (under load).
    • Inspect for proper installation of aftermarket electronic equipment. Incorrectly installed aftermarket electronic equipment may affect the integrity of other systems.