V70 2.5T AWD L5-2.5L Turbo VIN 59 B5254T2 (2003)
Viscous Coupling: Description and Operation
Design
Design
Control module
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 from the engine control module (ECM), the central electronic module (CEM) and the brake
control module (BCM) via the high speed side of the control area network (CAN). 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 not available if there is a fault in the differential electronic module (DEM).
Oil pressure and temperature sensor
The oil pressure and temperature sensor in the clutch unit are close to the axial solenoid in the housing for the differential control module (DEM). The
sensor is flushed with hydraulic fluid. The sensor gauges the temperature and pressure of the hydraulic fluid (measurement range 0-4 MPa). The sensor
