Grand Cherokee 4WD V8-5.2L VIN Y (1998)
Power Seat Control Module: Description and Operation
SYSTEM OPERATION
A Memory Seat Module (MSM), mounted under the inboard side of the driver side front seat cushion, is used on this model to control all of the
driver side power seat memory functions and features. The MSM contains a central processing unit and interfaces with other modules in the
vehicle on the Chrysler Collision Detection (CCD) data bus network.
The MSM receives hard-wired inputs from the power seat switch, the power lumbar switch, and the potentiometers on each of the driver side
power seat motors. The MSM receives messages on the CCD data bus from the Driver Door Module (DDM) (memory set/select switch status), the
Powertrain Control Module (PCM) (vehicle speed status), and the Body Control Module (seat belt switch status). The programming in the MSM
allows it to process the information from these inputs and send control outputs to each of the driver side power seat motors. The MSM will prevent
the seat memory function from heing initiated if the driver side seat belt is buckled, or if the vehicle is moving.
For diagnosis of the MSM or the CCD data bus, refer to the proper Computers and Control Systems/Body Control Module/Testing and Inspection
Procedures. The MSM cannot be repaired and, if faulty, it must be replaced.
