V70 2.4 L5-2.4L VIN 61 B5244S (2001)
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 (ECU), the central
electronic module (GEM) 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 multiplate 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 transmits signals about temperature and pressure to the control module. The control module uses the temperature and pressure signals to adapt
the function of the system, changing the temperature, and therefore the viscosity, of the fluid as required.
If the temperature of the fluid exceeds 100°C there is no pressure in the coupling and all wheel drive is disengaged. When the temperature falls below
100°C the coupling is pressurized again. If the oil pressure exceeds 7.4 MPa, the safety valve in the coupling opens. The coupling is pressurized again
when the oil pressure drops below 7.4 MPa.
Four wheel drive is not available if there is a fault in the pressure and/or temperature sensor.
There are diagnostics for the oil pressure and temperature sensor.
Control valve/axial solenoid