Memory Positioning Module: Description and Operation

Vehicles equipped with the memory seat/mirror option, utilize a memory module located under the drivers front seat. This module is basically wired in-line between the power seat switch and the power seat track/adjuster motors, or in-line between the power mirror switch and the power side view mirror(s) motor(s). The Memory Seat/Mirror Module (MSMM) contains a central processing unit that communicates with other modules on the Programmable Communications Interface (PCI) data bus network.

The MSMM receives hard wired inputs from the driver power seat switch and the potentiometers on each of the driver side power seat track motors, or from the power mirror switch and the potentiometers on the side view mirror. The MSMM receives messages over the PCI data bus from the Body Control Module (BCM) (memory switch status), the Powertrain Control Module (PCM) (vehicle speed status). The MSMM 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.

For diagnosis of the MSMM or the PCI data bus, a DRBIII(R) scan tool and the proper Diagnostic Procedures Information are recommended. The MSMM cannot be repaired and, if faulty or damaged, it must be replaced.

When memory system operation is requested (depressing of the memory switch), a resistor multiplexed signal is sent from the memory switch to the Body Control Module (BCM). The BCM will then send the appropriate signals out to the Memory Seat/ Mirror Module (MSMM), the MSMM then applies the voltage supply to the power seat track or side-view mirror if the proper requirements are met. The vehicle speed must equal zero and the transmission must be in park or neutral in order for the memory system to function.