> Relays and Modules > Relays and Modules - Body and Frame > Power Seat Control Module > Component Information > Technical Service Bulletins > Memory Power Seat - Travel Range
Power Seat Control Module: Technical Service BulletinsMemory Power Seat - Travel Range
NO: 08-44-98
GROUP: Electrical
DATE: Dec. 11, 1998
SUBJECT:Memory Power SeatTravel Range
MODELS:
1996-1999 (NS) Town & Country1996-1999 (GS) Chrysler Voyager1996-1998 (ZJ) Grand Cherokee1996-1998 (ZG) Grand Cherokee (International Market)
DISCUSSION:
The Memory Seat/Mirror Module (MSMM) (on ZJ/ZG the module is for the seat only) detects and remembers where the end of seat travel (called "softstop") is in each direction. A soft stop is set in MSMM memory when the position sensing feedback voltage, controlled by a potentiometer on the motorend, fails to change. The feedback voltage potentiometers vary the position sensing feedback voltage based on seat position/movement (no movement, nochange in position sensing feedback voltage). The seat motor automatically stops at the soft stop on any subsequent movement so the motor does not runinto a stall condition (end of travel).
The soft stop limits will be updated any time the MSMM senses a mechanical stall (such as when something is stuck under or behind the seat that causesthe seat to stop moving). These soft stops can prevent the seat from being able to have memory positions set over the full range of travel. Also, positionsthat were previously programmed to locations beyond an updated soft stop limit will not be recalled as they are "out of range."
When a new MSMM or seat track is installed into a vehicle, the soft stops must be programmed into the MSMM memory for proper operation, the lastparagraph of this TSB explains the procedure to properly set soft stops. Failure to properly set soft stops could result in intermittent memory seatoperation.
There are two potential reasons for intermittent memory functioning of the seats. The first possibility is the soft stops learned by the MSMM may need tobe reset. New soft stops are learned by the MSMM any time movement is restricted. (This could be as simple as hitting an obstruction in the seat's pathor a person shifting their body while a power seat motor is in operation.)
The second reason only applies to NS/GS-vehicles, intermittent operation of the memory seat can be caused by a poor connection at pin 23 of the P34connector which is located near the right side of the steering column. This circuit is used to communicate and control the seat module. This circuit "locksout" movement when the vehicle is not in park and also causes seat position recall when used with the Remote Keyless Entry (RKE) feature. The P34connector should be inspected for fully seated and clean contacts.
To check and reset the soft stop limits in memory, use the control switches on the side of the seat to move the seat in one direction to the end of travel,then energize the seat again in the same direction until it stops and for three additional seconds after it stops. The amount that the seat moved upon thesecond energizing is the amount the soft stop has been reprogrammed. Repeat this procedure for each of the directions of movement (one at a time).
:NOTE
IF THE SEAT TRACK ASSEMBLY OR MSMM HAVE NOT BEEN REPLACED, THIS METHOD OF SOFT STOP RESET LEAVES THECUSTOMER'S SETTINGS PROGRAMMED IN THE MSMM (AS OPPOSED TO USING DIAGNOSTIC MODES 1 AND 2 DESCRIBED INTHE SERVICE MANUAL).