Grand Caravan FWD V6-3.3L VIN 3 Flex Fuel (2002)
Memory Positioning Systems: 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). A button (either # 1 or # 2) pressed on the set switch causes the BCM to send a
message to the MSMM which in turn will send a motion status message back to the BCM. If the message from the MSMM indicates no current
motion, the BCM will send a recal message to the module. The MSMM will set the seat, exterior mirror and radio to the presets for the indicated
driver.
If any one of the memory controlled systems is inoperative from its manual switch, use the schematics and diagnostic information to correct the
concern. 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.
MEMORY MIRRORS
The driver sideview mirror contains vertical and horizontal bi-directional drive positioning motors and position sensors. The MSMM provides a 5-volt
reference on the signal circuit to each position sensor. The sensors share a common ground circuit. The MSMM monitors the position of the mirror
motors by measuring the voltage on each signal circuit. When a memory position is set, the MSMM monitors and stores the position of the outside
mirror. The MSMM adjusts the mirror to the appropriate positions when a memory recall message is received from the RKE or is requested from the
memory set switch.
The power mirror switch during non-memory operation operates the mirror independently of the MSMM.
