Voyager L4-2.4L VIN B (2001)
Power Seat Control Module: Description and Operation
MEMORY SYSTEM
The memory system consists of power driver's seat, power mirrors and radio presets. The Memory Seat/Mirror Module (MSMM) is located under
the driver's seat. It receives input from the following: driver's manual 8-way seat switch, driver's seat position sensors, PCI bus circuits, and the
power mirror sensors. The module uses these inputs to perform the following functions: position the driver's memory seat, both exterior mirrors
(during recalls), and send/receive the memory system information over the PCI bus.
The Memory Set Switch is wired to the Body Control Module (BCM). When a button (either #1 or #2) is pressed on the set switch causes the to
BCM send a message to the MSMM which in turn sends a motion status messages to the BCM. If the BCM receives no motion from the MSMM it
will send a recall message to the MSMM and radio (once ignition is in run or accessory). The MSMM will in turn position the drivers seat, both
mirrors along with recalling the radio presets. If the drivers seat or either exterior mirror is inoperative from its own respective switches, use the
service information and schematic to diagnose the problem. This manual addresses the memory problems only and it is assumed there is not a
basic component failure.
Power Seat
The memory power seat provides the driver with 2 position settings for the driver's seat. Each power seat motor is connected to the MSMM with
two motor drive circuits. Each circuit is switched between battery and ground. By being able to bi-directionally drive the circuits, the MSMM
controls the movement of the motors based on input from the power seat switch or from the position sensors when performing a memory recall.
Each motor contains a potentiometer to monitor the seat position. To monitor the position of the motor, the MSMM sends out a 5-volt reference
on the sensor supply circuit. The sensor is grounded back to the module on a common ground circuit. Based on the position of the sensor, the
MSMM monitors the voltage change through the sensor on a separate signal circuit.
The MSMM stores the input value of each of the four seat potentiometers in memory when the system requests a set. The driver can initiate a
memory recall, using either the door mounted memory switch or the RKE transmitter (if the remote linked to memory feature is enabled via the
EVIC). When initiated, the MSMM adjusts the four seat sensors (by using the motors) to match the memorized seat position data.
For safety, the memory seat recall is disabled by the MSMM when the vehicle is out of park position or if the speed is not zero. Any obstruction to
seat movement over a 2-second delay will cause the seat to stop moving in which case a stalled motor would be detected by the MSMM and the
corresponding seat output would be deactivated. However, if the object obstructing the seat is removed, the seat will function normally again.
