Vehicle Speed
While driving, the brake control module (BCM) (4/16) registers the acceleration and deceleration of the wheels. The 4 wheel sensors (7/31-32 and 7/56-57) (one on each wheel) provide the brake control module (BCM) with information about the rotation speed of each wheel. The brake control module (BCM) calculates the actual speed of the car using this information and puts it out on the controller area network (CAN). The vehicle speed signal is used by the Power Steering Control Module (PSCM) (6/164) so that, when combined with other parameters, it can calculate the optimal desired value for the pump motor speed. The system reduces the speed of the pump motor (=reduced hydraulic pressure) when the vehicle speed increases. The pump motor speed increases (=increased hydraulic pressure) as vehicle speed drops. This to obtain optimal steering assistance in relation to vehicle speed. This is speed dependent power steering.