Cooling Fans

The cooling fans are operated by a fan control module which is located at the rear of the left cooling fan motor. The fan control module regulates the voltage, and subsequently the speed, of the cooling fan motors in response to a pulse width modulation (PWM) signal from the engine control module (ECM). The ECM calculates the required fan speeds from the engine temperature, A/C system pressure and transmission fluid temperature. Under hot operating conditions, the fans may continue to operate for up to four minutes after the engine has been switched off.

The speed of the cooling fans is also influenced by vehicle road speed. The ECM adjusts the speed of the cooling fans, to compensate for the ram effect of vehicle speed, using the HS (high speed) controller area network (CAN) chassis bus road speed signal received from the anti-lock brake system (ABS) control module.