Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Cooling Fan / Engine Cooling Fan Control Module
The engine cooling fan consists of a control module and one or two fans, depending on the vehicle version.
The engine cooling fan has two functions; to cool the engine compartment and to cool the condenser when the air conditioning (A/C) compressor is working.
The Engine cooling fan control module is powered with 12V through the relay/fusebox engine compartment and grounded at the body frame.
The Engine Control Module (ECM) sends a PWM signal (12V) to the Engine cooling fan control module. The engine cooling fan control module in turn transmits a pulse width modulated (PWM) signal to activate the fans at different speeds. The speed is determined by the Engine Control Module (ECM), depending on the cooling demand.
The Engine cooling fan control module monitors the function of the fan with its motor. Using an internal communication interface, the Engine Control Module (ECM) is continually informed about the fan status.
The engine cooling fan is diagnosed by the Engine Control Module (ECM) and the fan speed can be read out and controlled.
The engine cooling fan may have a post-run of up to approx. 6 minutes after the engine has been turned off. The time for the fan's post-run depends on engine temperature, temperature in the engine compartment and pressure level in the AC-system.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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