High Speed Fan Control Relay Circuit

Name of Code:
High Speed Fan Control Relay Circuit

When Monitored:
With the ignition key in the run position and battery voltage above 10 volts.

Set Condition:
An open or shorted condition is detected in the high speed fan relay control circuit.

Theory of Operation:
The high speed fan relay controls the high speed operation of the radiator fans. The relay is located in the power distribution center. One side of the relay control coil is supplied with 12 volts when the ignition switch is turned to the run position. The circuit is completed when the other side of the relay coil is grounded by the powertrain control module (PCM). The PCM grounds the relay control circuit when the engine coolant temperature is too high and removes the ground when the temperature is acceptable.

Possible Causes:
- Relay coil open or shorted
- Fused ignition switch output circuit open
- High speed fan relay control circuit is open or shorted
- Inoperative circuit driver in powertrain control module