Driver Power Seat Operation

The driver seat control switch communicates over a LIN to the DSM. When the DSM receives the input from the seat control switch, the DSM provides power the appropriate seat motor until the input is removed. The motor circuits are normally grounded through the DSM. The DSM internally switches the appropriate circuit from ground to voltage to operate the motors.

As the seat is adjusted, the DSM monitors the motor position sensors to record the current seat position. The DSM removes voltage from the motor upon termination of the seat control switch input or if the DSM does not detect movement from the motor while monitoring the position sensor during a memory recall operation.

If the DSM loses the signal from any of the motor position sensors, the affected seat motor operates in jog mode. Jog mode allows limited operation of the affected seat motor using only the seat control switch. When the seat control switch is operated in jog mode, the seat moves in the desired direction for one second, then stops. The seat control switch must be released, then pressed again in order to move the seat for an additional second. Jog mode is an indication that there is a seat motor sensor fault. If the memory seat is operating in jog mode, a DTC sets in the DSM.

DSM Hard Stop/Soft Stop 

A hard stop occurs when one of the memory seat track or backrest axes physically reach the end of travel and can go no further. A soft stop occurs when the seat stops before it physically reaches the end of travel. The hard stop is set by seat design and cannot be changed or adjusted. The soft stop is set by the DSM. The seat track axes are forward/rearward, front up/down and rear up/down. The backrest axis is recline forward/backward. If equipped with 24-way or 30-way seats, there are additional axes for the cushion extension (forward/rearward) and head restraint (forward/rearward and up/down). To prevent unnecessary stress on the seat and motors, the DSM sets soft stop positions, 2 for each axis of motion. The DSM uses a preset distance from the hard stop to determine where the soft stop occurs. When an axis reaches the hard stop and the switch is held for approximately one second, the DSM establishes the soft stop for that axis in that direction.