Driver Power Head Restraint Operation

The power head restraint assembly contains a seat headrest motor (up/down) and a seat head restraint forward/rearward motor. 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 head restraint 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.

If the DSM loses the signal from any of the motor position sensors, the affected head restraint motor operates in jog mode. Jog mode allows limited operation of the affected head restraint motor using the seat control switch. When the seat control switch is operated in jog mode, the head restraint 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 head restraint for an additional second. Jog mode is an indication that there is a head restraint motor sensor fault. If the head restraint is operating in jog mode, a DTC sets in the DSM.

As the driver seat head restraint 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.

Easy Entry/Exit 

The easy entry/exit feature is a function of the DSM that moves the driver seat back approximately 50.8 mm (2 in) (unless seat is already positioned at or near the end of travel) when the ignition is turned off. The DSM receives ignition off status over the MS-CAN and operates the driver seat rearward. The DSM cancels this operation if a valid input command is received from the driver seat control switch, memory set switch, exterior mirror control switch or if the function has been disabled.

The DSM records the current seat positions before operating the seat for an easy exit operation. During easy entry operation (when the ignition is turned on), the seat is returned to the recorded seat position prior to the easy exit operation. Easy entry operation is cancelled if a valid input command is received by the DSM. A memory position recall using the memory set switch also overrides the easy exit operation.

The easy entry/exit feature can be enabled/disabled on the message center. For information on programming vehicle settings in the message center, refer to the Owner's Literature.