Chart C-12, Cooling Fan Control (3.1L - VIN D, "U" Body): Notes
The ECM controls cooling fan by inputs from coolant temperature sensor (located in front of distributor on left side of engine), A/C fan control switch, and vehicle speed. The ECM grounds the circuit to fan control relay which is the center relay located on right side of engine compartment behind the headlight. This energizes fan control relay for fan operation. Wiring circuit to fan control relay is grounded when coolant temperature exceeds 223°F (106°F) or when A/C is operating and A/C fan control switch opens with high A/C pressure of approximately 200 psi (14.1 kg/cm2 ).
NOTE:
Test numbers refer to test numbers on diagnostic charts.
- With diagnostic terminal grounded, cooling fan driver closes and energizes fan control relay.
- If A/C fan control switch or circuit is open, cooling fan operates whenever A/C is operating.
- With A/C clutch energized, A/C fan control switch should open when A/C high pressure exceeds 200 psi (14.1 kg/cm2 ). This signal indicates that ECM should energize fan control relay.
- With ignition on, 12 volts should exist at terminals "A" and "D" of fan control relay.
- This verifies ECM ability to ground the fan control relay. The "SERVICE ENGINE SOON" light should be flashing. If light fails to flash, check wiring circuit. See appropriate article in ENGINE PERFORMANCE section.
- If cooling fan does not operate, open circuit exists between fan control relay or between A/C fan control switch and ground.