Calais V6-3300 3.3L MFI VIN N (1990)
Chart C-12 & C-12A 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 pressure is above 170 psi value.
^
The coolant temperature is greater than 100~C (212~F).
TEST DESCRIPTION:Numbers below refer to circled numbers on the diagnostic chart.
1.
Fan should be on as using the scanner to turn on the QDM and provide a ground path for current to flow through relay coil.
2.
The fan should be running if the A/C pressure is above 170 psi as the ECM monitors B+ at terminal BC9 when A/C is requested.
DIAGNOSTIC AIDS:
^
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.
Part 2 of 3
