Speed Sensitive Power Steering
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2009 Volvo S60, 2008 Volvo S60, 2007 Volvo S60, 2006 Volvo S60, and 2005 Volvo S60. However, it is still accessible from the selected car via links, so may be relevant.
If the car has speed dependent power steering to control the steering assistance, there is a stepper motor which controls a hydraulic valve on the steering gear.
The stepper motor is operated by the central electronic module (CEM) and checked via four outputs in the central electronic module (CEM). Signals are transmitted from the central electronic module (CEM) to set the motor to the correct position for the speed of the car. The motor deploys the valve on the steering gear to the required degree and regulates the oil in the steering gear to reduce or increase the servo assistance. The steering assistance increases at lower speeds and is reduced at higher speeds.
There are diagnostics for the power steering.