Control Module

Fig 1: Differential Electronic Module (DEM)

Courtesy of VOLVO CARS CORPORATION

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 system 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.