Radiator Cooling Fan Motor Relay: Description and Operation
RADIATOR FAN RELAYS - PCM OUTPUTThe low speed and high speed fan relays are located in the Power Distribution Center (PDC) near the battery. A decal on the inside of the PDC covers shows the locations of each relay and fuse contained in the PDC. It is an ISO relay.
The cooling system uses two fans. Both fans operate at two different speeds, low and high. Depending on engine coolant temperature and A/C system high side pressure, the both fans operate at either low or high. The PCM controls radiator speed by grounding the coil side of either the low speed fan relay or the high speed fan relay. The ignition switch supplies voltage to the coil sides of the relay. When the PCM grounds the coil side of the relay, the contacts close and the battery supplies power to the fans.