Theory Of Operation

WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.

This two speed cooling fan system uses a Low Speed Fan Relay and Hi Speed Fan Relay to control the cooling fan operation.

During low speed mode: The Powertrain Control Module (PCM) grounds the Low Speed Fan Relay Control circuit, closing the relay to connect Battery voltage to the Cooling Fan Motor Output circuit. The Cooling Fan Motor Output circuit supplies 12.0 volts DC to a cooling fan resistor, current flows through the resistor, reducing the voltage to the Cooling Fan Motor allowing low speed operation. The Cooling Fan Ground circuit provides a direct path to ground for the Cooling Fan.

During High speed mode: The PCM grounds the High Speed Fan Relay Control circuit, closing the relay to connect Battery voltage to the Cooling Fan Motor Output circuit. The Cooling Fan Motor Output circuit supplies 12.0 volts DC directly to the Cooling Fan Motor, bypassing the resistor, allowing high speed operation. The Ground circuit provides the ground path for the Cooling Fan.