Radiator Cooling Fan Motor Relay: Description and Operation

PURPOSE
The Radiator Fan Control Relays Operate the cooling fans, and allows the Engine Control Module (ECM) to have precise control over the speed at which the radiator fan(s) operate.


OPERATION

Radiator fan speed is controlled by the ECM grounding one of the three radiator fan relays.

Main Relay:

Relay 1
Used to control Cooling Fan low speed. Voltage applied across terminals 1 and 2 cause the switch contact to close terminals 5 and 3.

Relay Test:

Relay 2, 3
Used to control Cooling Fan High speed. Voltage applied across terminals 1 and 2 cause the switch contact to close terminals 5 and 3, as well as terminals 6 and 7.