Camaro V8-350 5.7L (1989)
Chart C-12 Wiring Diagram
CIRCUIT DESCRIPTION:
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The primary cooling fan is totally controlled by the ECM based on inputs from the coolant sensor and fan control switch. The fan should run
if coolant temperature is greater than 106~C (223~F).
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Battery voltage is supplied to the fan relay on terminal "E" and ignition voltage to terminal "D".
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Grounding CKT 335 (relay terminal "F") will energize the relay and supply battery voltage to the fan motor. Once the fan relay is energized
by the ECM, it will remain "ON" for a minimum of 15 seconds.
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The ECM will remove the ground to CKT 335 if vehicle speed is over 40 mph unless the engine is overheating.
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The fan control switch, mounted in the A/C high pressure line, will close when head pressure exceeds 233 psi (1600 kPa) and this input
causes the ECM to ground CKT 335.
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If a Code 14 or 15 sets or the ECM is operating in the fuel back-up mode, the ECM will turn "ON" the cooling fan.
DIAGNOSTIC AIDS:
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If the owner complained of an overheating problem, it must be determined if the complaint was due to an actual boil over or the hot light or
temperature gauge indicated overheating.
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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" tool and comparing its reading with the gauge reading.
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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.
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If the engine is overheating, and the cooling fan is "ON," the cooling system should be checked.
Part 2 of 2
