GM Service Manual Online
For 1990-2009 cars only

Memory Seat System Components

The memory seat system consists of the following components:

    • Power seat switch
    • Seat horizontal motor
    • Seat front vertical motor
    • Seat rear vertical motor
    • Seat recliner motor
    • Driver seat module
    • Memory seat switch

Memory Seat System Description

Battery voltage is supplied to the driver seat module (DSM) through the power seat circuit breaker. The DSM supplies the seat adjuster switch assembly with a battery positive reference voltage. When a seat adjuster switch is pressed to an active state the switch contact is closed to the reference voltage circuit. Battery voltage on a switch signal circuit indicates to the DSM the switch status is active. Each seat adjuster motor is controlled by the DSM through 2 motor control circuits. While the seat adjuster motors are in an inactive state the motor control circuits are closed to ground circuit contacts within the DSM. The DSM operates the seat adjuster motors by switching one of a motor's control circuits to battery voltage. The seat adjuster motors are bidirectional and the direction of adjuster motor rotation is determined by which of the adjuster motor control circuits is switched to battery voltage while the other remains grounded.

Memory Set/Recall Operation

The driver seat adjuster motors are equipped with internal potentiometer type position sensors. The adjuster motor position sensors are monitored by the DSM and are used to determine the seat position when storing or recalling memory settings. The front vertical, rear vertical, horizontal, and recline position sensors are supplied with common 5-volt reference and ground circuits from the DSM. The position sensor signal circuits are supplied 5 volts through resistors then monitored within the DSM. The signal voltages monitored by the DSM range from 0.39-4.58 volts and are determined by the wiper locations on the resistors within the position sensors. The position sensor signal circuit voltage levels are used by the DSM to determine the seat position when storing or recalling memory seat position settings.

The memory switch assembly provides inputs to the DSM. Battery voltage is supplied to the memory switch assembly from the seat module. When a memory 1, 2, or EXIT switch is pressed, the switch contacts close the appropriate switch signal circuit to the battery voltage supply circuit within the memory switch assembly. When the seat module receives active switch signals from the memory switch assembly, the appropriate seat adjuster motors are operated, as necessary, until the position sensor signal voltages match the stored values.

Memory seat recall operation, while the ignition is ON, is allowed only with the transmission selector lever in the PARK position. The transmission selector lever position data is provided to the DSM by a message through the class 2 Serial Data circuit.