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.
Control Module
The differential electronic module (DEM) is secured directly to the coupling unit's housing and makes up unit with the pressure reducing valve. The control module and the pressure reducing valve are calibrated together at the factory and can therefore only be replaced together.
Via the controller area network (CAN), the differential electronic module (DEM) receives signals from:
- Engine control module (ECM)
- Central electronic module (CEM)
- Brake control module (BCM)
- driver information module (DIM).
Conducted by these signals, the Differential Electronic Module (DEM) determines how high the oil pressure to the clutch unit should be. The oil pressure to the clutch driven plates is decisive for how much torque can be transferred to the rear wheels.
In case of Differential electronic module (DEM) failure, four-wheel drive may be reduced or lost completely.
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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.