Driver's Seat (E38/E39): Notes

Each motor for seat adjustment contains a micro-processor (called a Ripple Counter) that receives a digital signal from the seat control module for motor activation. The motors are connected to KL 30 and KL 31 and respond to the signals generated by the seat module when seat movement is requested. The seat adjustment switch provides ground input signals to the module when seat movement is desired. The module processes these input signals and sends output signals to the seat motor processors. The seat motor processors activate the motors and the seat moves to the desired point.

The circuitry of the Ripple Counter detects the motor activation current. As the armature segments of the motor rotate passed the brushes, the current flow rises and falls producing a ripple effect. The peaks of these ripples are counted and stored in the Ripple Counter module. The memory function of the seat module uses this ripple count instead of feedback potentiometers to memorize and recall seat positions.