Grand Cherokee 2WD Limited V8-4.7L (2002)
Power Mirror Control Module: Description and Operation
MEMORY HEATED SEAT/MIRROR MODULE
There are two different modules that can be used in the optional heated seat system. The Heated Seat Module (HSM) is used on vehicles that are
not equipped with the optional Memory System. The Memory Heated Seat Module (MHSM) is used on vehicles that are equipped with the
optional Memory System and the optional heated seat system. Refer to Memory System in Power Seat Systems for more information on the
memory system option.
Heated Seat Module Remove/Install
The module is mounted on a bracket that is located between the power seat track and the seat cushion frame. The HSM or MHSM is used to
control the heated seat system functions for both front seats. The HSM or MHSM contains a central processing unit that communicates with other
modules on the Programmable Communications Interface (PCI) data bus network.
For diagnosis of the HSM, MHSM or the PCI data bus, a DRB III scan tool and the proper Diagnostic Procedures are recommended. The HSM or
MHSM cannot be repaired and, if faulty or damaged, it must be replaced.
The MSM receives hard wired inputs from the power seat switch and the potentiometers on each of the driver side power seat motors. The MSM
receives messages over the PCI data bus from the Driver Door Module (DDM) (memory switch status), the Powertrain Control Module (PCM)
(vehicle speed status), and the Body Control Module (seat belt switch status).The MSM will prevent the seat memory recall function from being
initiated if the driver side seat belt is buckled, if the transmission gear selector lever is not in the Park or Neutral positions, or if the vehicle is
moving.
