Engine Cooling Fan Control

The PCM controls operation of the engine cooling fan based on coolant temperature, air conditioning state and vehicle speed. If the coolant rises above 223°F (106°C) or if the air conditioning compressor is turned on, the PCM will supply a ground to the engine coolant fan relay, energizing the relay and engine cooling fan. The PCM will shut off the cooling fan if the vehicle exceeds 70 MPH (97 KM/H) for three minutes.

When the PCM stops receiving an A/C request signal, it will run the cooling fan for one minute, then de-energize the relay, which will turn off the cooling fan. The A/C high or low pressure switches open the A/C request circuit from the A/C control head to the PCM. The cooling fan is turned on, after the initialization delay, when any of the following conditions are present: An ECT failure has been detected (DTCs P0117, P0118, P0125, P0217, P1114, P1115 and P1620).

When coolant temperature exceeds 230°F (110°C) or vehicle is turned OFF, and ECT temperature is 230°F (110°C) or greater, the cooling fan will be turned ON.