P1490 Low Speed Fan Control Relay Circuit

NAME OF CODE
Low Speed Fan Control Relay Circuit

WHEN MONITORED
With the ignition key on and battery voltage greater than 10 volts.

SET CONDITION
An open or shorted condition is detected in the low speed radiator fan relay control circuit.

THEORY OF OPERATION
The low speed radiator fan relay controls the low speed operation of the radiator fan. When the vehicle is equipped with a power distribution center (PDC), the low speed radiator fan relay is inside the PDC. One side of the relay control coil is supplied with 12 volts when the ignition switch is in 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 will actuate the relay whenever the A/C clutch is engaged regardless of coolant temperature and vehicle speed. If the A/C clutch is not engaged, the PCM will actuate the relay when the coolant temperature reaches approximately 207°F and turn off the relay when the coolant temperature drops to approximately 201°F. The relay is also turned off when the vehicle speed is above 62 MPH and A/C clutch is disengaged.

POSSIBLE CAUSES
- Relay coil open or shorted
- Fused ignition switch output circuit open
- Low speed radiator fan relay control circuit open or shorted
- Inoperative circuit driver in powertrain control module