Radiator Cooling Fan Control Module: Description and Operation

The cooling fan module contains two internal relays that are controlled by the ECM. The ECM controls two wires that supply a ground for the relays. Each control wire does not ground a separate relay; however, the combination of two discrete wires allow for different fan speeds. Eased on coolant temperature and A/C system pressure, the ECM can command low, medium, and high speed fan operation. If engine coolant temperature exceeds 105°C (221°F) at ignition Off, the two fans will run along with the auxilliary water pump for two minutes.