Electrical Feed Pump
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.
The electrical feed pump is integrated in the coupling unit and is powered by the differential electronic module (DEM). When the engine is started and exceeds 400 rpm, the electrical feed pump receives power from the control unit.
The feed pump pumps oil to the annular pistons, whose rollers move into contact with the cam disc. At the same time the oil flows to the operating piston, so that the play in the multi-plate clutch unit is eliminated. The coupling is then able to react rapidly and regulate as required.
Four wheel drive is disengaged if there is a fault in the feed pump.
There are diagnostics for the feed pump.