Temperature calculation
There is a temperature sensor on the control module's circuit board and the value from this, together with information on prevailing driving conditions, is used in a formula to calculate the temperature of the fluid in the differential clutch. The temperature inside the clutch pack itself is also calculated.
If the temperature of the differential clutch fluid reaches critical values then all-wheel drive is switched off, this protects against further temperature increase.
Fluid viscosity (thickness) varies with temperature, because of this the current to the pressure control valve must be compensated. In principle it takes a longer time to apply the clutch at low temperature compared to when the fluid is at normal operating temperature.