Part 1 of 2

Chart C-12 Part 1 Of 2:

Cooling Fan Control:

CIRCUIT DESCRIPTION
Battery voltage to operate the cooling fan #1 motor is supplied to cooling fan #1 control relay by CKT 342. Ignition voltage to energize cooling fan #1 control relay is supplied by CKT 540. When the PCM grounds CKT 335, the relay is energized and the cooling fan #1 is turned "ON."
When the engine is running, the PCM will turn the cooling fan "ON" for any of the following reasons:

^ Diagnostic Trouble Code 14, 15 or 70 is set.
^ A/C is requested and vehicle speed is less than 50 mph (81 km/h).
^ Coolant temperature is 108°C (226°F) or greater, with A/C "OFF". (106°C (223°F) with A/C "ON").
^ A/C pressure is 1275 kPa (185 psi) or greater.


Once the cooling fan is enabled, the PCM will turn the fan "OFF" when:

^ Engine is turned "OFF".
^ Engine coolant temperature drops to 104°C (210°F) or less.
^ A/C refrigerant pressure drops to 189 psi or less with A/C selected.

DIAGNOSTIC AIDS:
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.

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 checking the engine coolant temperature display using a scan tool and comparing its display with the instrument cluster gauge.

If the engine is actually overheating and the gauge indicates overheating, but the cooling fan is not coming "ON," the ECT sensor has probably shifted out of calibration and should be replaced.