XC90 AWD L6-2.9L Turbo VIN 91 B6294T (2004)
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
The control valve/axial solenoid are in the coupling unit for the active on demand coupling (AOC).
The axial solenoid receives a constant pulse width modulated (PWM) signal from the control module. The control signal from the control module is used
by the solenoid to change the position of the control valve. This regulates the pressure to the operating piston in the multi-plate clutch.
Four wheel drive is disabled if there is a fault in the control valve/axial solenoid.
There are diagnostics for the control valve/axial solenoid.
Electrical feed pump
