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.
Cooling fan for control modules
The engine control module (ECM) is in a control module box in the engine compartment. The transmission control module (TCM) is also in this box in vehicles with automatic transmissions.
The function of the cooling fan is to cool the control modules in the control module box in the engine compartment. The control modules may be damaged if they overheat.
A temperature sensor is integrated in the engine control module (ECM). The engine control module (ECM) activates the fan if the control module registers that the temperature is too high. The fan then runs continuously until the temperature has dropped to a normal level.
The cooling fan is in the hose between the control module box and the firewall.
The engine control module (ECM) can diagnose the cooling fan. The fan can be activated using VIDA.
A diagnostic trouble code (DTC) is stored if the temperature in the engine control module (ECM) gets too high.
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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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