Memory Seats
Memory Seats Description and Operation
The memory seat system consists of the following components:
* Memory seat module
* Driver door module
* Driver seat adjuster switch
* Driver seat lumbar adjuster switch
* Driver memory/heated and cooled seat switch
* Driver seat horizontal motor
* Driver seat front vertical motor
* Driver seat rear vertical motor
* Driver seat recline motor
* Driver seat lumbar horizontal motor
* Driver seat lumbar vertical motor
* Driver seat horizontal motor position sensor
* Driver seat front vertical motor position sensor
* Driver seat rear vertical motor position sensor
* Driver seat recline motor position sensor
* Driver seat lumbar horizontal motor position sensor
* Driver seat lumbar vertical motor position sensor
Memory Recall Option
The memory seat module (MSM) cannot perform Memory Seat Recall and Easy Exit functions unless these options are activated in the driver information center (DIC). The DIC reports the memory recall option setting to the MSM, as well as other receiving modules, via GMLAN message each time the ignition switch is cycled to the ON position. The MSM will then store the memory recall option setting and examine it before making a memory seat adjustment. The memory recall option setting stored within the MSM will not change until the memory recall option setting in the DIC is changed and the ignition switch is cycled to the ON position.
Power Seat and Lumbar Switches
Battery positive voltage is supplied at all times to the driver seat adjuster switch and lumbar adjuster switch from the MSM and a 10 A fuse located in the rear fuse block. When the seat or lumbar switches are pressed they send a 12 V signal to the MSM. The MSM commands the selected seat or lumbar motor to move in response to the switch inputs.
MSM Power and Grounds
Battery positive voltage is supplied at all times to the MSM through two different 25 A circuit breakers located in the rear fuse block. One circuit breaker is used by the MSM to apply power to the driver seat horizontal motor, front vertical motor, rear vertical motor, recline motor, and the lumbar horizontal motor. The second circuit breaker is used by the MSM to apply power to the driver seat lumbar vertical motor, and the steering wheel and column motors. Battery positive voltage is also supplied at all times to the MSM through a 10 A fuse located in the rear fuse block. This voltage is used to power up the MSM. Ground is provided to the MSM through two separate ground circuits that are connected to a common ground.
MSM Controlled Motors
The MSM controls all seat, lumbar, and steering wheel and column motors via half bridges that are divided into 2 groups as mentioned above. Each group is connected to a separate power rail internal the module. The MSM connects all motor outputs for each power rail to a common reference point whenever they are not in operation. This reference point is biased to approximately 2.5 V. The MSM checks to see if this reference voltage is shorted to ground or battery voltage before enabling any seat, lumbar, or steering column motor. All of the motors operate independently of each other. Each motor contains a electronic circuit breaker (PTC), which will reset only after voltage has been removed from the motor.
All MSM controlled motors are reversible. For example, when a seat switch is pressed to move the entire seat forward, battery voltage is applied through the switch contacts, the seat horizontal forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery voltage through the driver seat horizontal motor forward control circuit and ground through the driver seat horizontal motor rearward control circuit to the motor. The motor runs in order to drive the entire seat forward. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction. All of the motors are powered this way.
Position Sensors
The position sensors are potentiometers which are either attached directly to the motor transmission cable or are an internal part of the motor. The MSM supplies a 5 V reference through the 5 V reference circuit and ground through the sensor low reference circuit to the respective seat, lumbar, and steering wheel and column position sensors. For more information regarding the steering wheel and column operation, refer to Steering Wheel and Column Description and Operation (Description and Operation). When the motor or cable rotates, the resistance of the potentiometer varies changing the feedback voltage of the position sensor signal circuit. The voltage varies from 0.22 - 4.75 V. The MSM monitors this voltage signal to determine the position of the seat. When a memory set command is received, the MSM records the seat position by storing the feedback voltage from each position sensor. Then when a memory recall command is received, the MSM moves the motors until the position sensor feedback voltages equals the feedback voltages stored in memory.
Memory Functions
Battery voltage is supplied at all times to the driver memory/heated and cooled seat switch from the driver door module (DDM) that is located on the driver door panel. When a memory switch is pressed, battery voltage is applied through the switch contacts, a series of resistors, and the memory recall switch signal circuit to the DDM. In response to this signal, the DDM sends a serial data message to the MSM indicating the memory request.
Memory positions may be recorded for 2 different drivers. To record a position, adjust the driver's seat, lumbar support, and steering wheel and column to the desired position. Press and hold the memory 1 button until two beeps sound indicating that the position has been stored to memory. A second memory position may be programmed by repeating the above steps and pressing button 2, for driver 2. When the MSM receives a memory set message, it records the feedback voltages from the seat, lumbar, and steering wheel and column position sensors for the appropriate driver.
When a memory recall button is pressed, a single beep will sound to acknowledge the command has been received. The MSM will then move the appropriate seat, lumbar, and steering wheel and column motors until the position sensor feedback voltages equal the feedback voltages stored in memory for the identified driver.
Memory recall operation is disabled if the shift lever is out of NEUTRAL (N) or PARK (P). The MSM receives the transmission selector position data via the GMLAN Serial Data circuit.
Easy Exit
If the EASY EXIT SEAT function is activated in the DIC as mentioned above, the driver seat will automatically move rearward approximately 3 inches when the key is removed from the ignition. If desired, the seat may be moved further by pressing the EXIT button. The seat will move approximately 3 inches each time the EXIT button is pressed until it reaches its end of travel. When the EXIT button is pressed, a single chime will sound in order to acknowledge the command. The Easy Exit incremental movement distance cannot be adjusted; it is pre-programmed at the factory.
Recall Personalization
* Recall upon receipt of the RKE message
* Recall upon receipt of the remote start feature
* Easy exit
* Factory settings
Memory Inhibit/Enable
The MSM receives the ignition switch signal and the gear selector position via GMLAN messages. When the ignition switch is in the OFF position, memory record, memory recall, personalization recall, and exit recall functions are all allowed. When the ignition switch is in the ON position and the gear selector is in the PARK position, only the recall personalization function is deactivated and all other memory functions are allowed. When the ignition switch is in the ON position and the gear selector is out of the PARK position, only memory record is allowed, all other memory seat functions are not allowed.