Control Module

Fig 1: Identifying Differential Electronic Module (DEM)

Courtesy of VOLVO CARS OF NORTH AMERICA.

The differential electronic module (DEM) is secured directly to the coupling unit housing and forms a single unit with the axial solenoid. The axial solenoid controls the control valve.

The differential electronic module (DEM) receives signals on the high speed side of the controller area network (CAN) from:

• engine control module (ECM)
• central electronic module (CEM)
• brake control module (BCM).

The differential electronic module (DEM) uses these signals to determine the oil pressure required for the multi-plate clutch in the coupling unit. The oil pressure for the multi-plate clutch determines the amount of torque which can be transferred to the rear wheels.

Four-wheel drive is disengaged if there is a fault in the differential electronic module (DEM).