Circuit/System Description (LCS)
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
The engine control module (ECM) commands the cooling fans depending on cooling requirements. The ECM controls the cooling fan speed by commanding the cooling control module. The cooling fan control module supplies the power and ground circuits for both cooling fans. The ECM sends a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module interprets the signal and operates the cooling fans at the commanded speeds.