Skylark V6-204 3.3L VIN N FI (1989)
Chart C-12B Wiring Diagram
CIRCUIT DESCRIPTION:
Battery voltage to operate the cooling fan motor is supplied to relay terminal "1". Ignition voltage to energize the relay is supplied to relay terminal "2".
When the ECM grounds CKT 535, the relay is energized and the cooling fan is turned "ON".
When the engine is running, the ECM will turn the cooling fan "ON" if the conditions for a coolant temperature sensor trouble code (14 or 15) are
present or:
^
The A/C is "ON" and vehicle speed is less 30 mph (48km/h).
^
The coolant temperature is greater than 100~C (212~F).
TEST DESCRIPTION:
1.
The coolant fan runs continuously if codes 14, 15 and/or 66 are present.
2.
CKT 535 has to be grounded or QDM inside ECM is faulty if test light is "ON."
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 boilover, or the hot light, or
temperature gauge indicated over heating.
^
If the gauge, or light, indicates overheating, but no boilover is detected, the gauge circuit should be checked. The gauge accuracy can, also, be
checked by comparing the coolant sensor reading using "Scan" tool and comparing its 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.
