Power Mirror Control Module: Description and Operation

MEMORY HEATED SEAT/MIRROR MODULE
There are two different electronic 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. A third electronic module, the Memory Seat Module (MSM), is used on vehicles equipped with the Memory System without 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:

All three modules are packaged in an identical molded plastic housing which is mounted on a bracket that is located between the power seat track and the seat cushion frame under the forward edge of the driver side front seat cushion. The HSM or MHSM is used to control all of the heated seat system functions for both front seats. The HSM or MHSM contains a central processing unit and interfaces with other electronic modules in the vehicle on the Programmable Communications Interface (PCI) data bus network.

For diagnosis of the HSM, MHSM or the PCI data bus, a DRB(R) 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 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 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.