Principles of Operation
Principles of OperationCooling Fans
The cooling fans are controlled by 4 relays to provide 3 speeds. If DTC P1474, P1477 or P1479 are present, refer to Computers and Control Systems for diagnosis.
In HIGH speed, the cooling fans are wired parallel and these relays are grounded by the PCM:
^ Fan braking relay
^ Engine cooling fan relay
In MEDIUM speed, the cooling fans are wired parallel through a resistor and this relay is grounded by the PCM:
^ Fan braking relay
In LOW speed, the cooling fans are wired in series and these relays are grounded by the PCM:
^ Fan braking relay
^ Engine cooling fan relay
^ HEDF and EDF relay