For 1990-2009 cars

The Memory Seat System consists of the following components:

• | Memory seat module (MSM)

• | Seat horizontal motor

• | Seat front vertical motor

• | Seat rear vertical motor

• | Seat recline motor

• | Lumbar horizontal motor

• | Lumbar vertical motor

• | Seat horizontal position sensor

• | Seat front vertical position sensor

• | Seat rear vertical position sensor

• | Seat recline position sensor

• | Lumbar horizontal positional sensor

• | Lumbar vertical position sensor

• | Seat adjuster switch

• | Seat lumbar switch

• | Memory recall switch

• | MSM/LT FRT PWR SEAT Circuit Breaker 25 A

• | MEM LOGIC/RF MASSAGE Fuse 10 A

### Memory Recall Option

The memory seat module (MSM) cannot perform memory recall functions unless the Memory Seat Recall option is activated. The memory seat recall option is located in the driver information center (DIC). The DIC reports the memory seat 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 Switches

Battery positive voltage is supplied at all times to the seat adjuster switch from the memory seat module (MSM) and the MEM Logic/RF MASSAGE fuse located in the rear fuse block. When the seat switches are pressed they send a 12-volt signal to the MSM. The MSM then commands the selected seat motor to move in response to the switch input.

### MSM Power and Grounds

Battery positive voltage is supplied at all times to the memory seat module (MSM) from the following circuit breaker and fuse located in the rear fuse block:

• | MSM/LT FRT PWR SEAT Circuit Breaker: This voltage is used by the MSM to apply power to the driver seat and lumbar motors when commanded.

• | MSM LOGIC/RF MASSAGE Fuse: This voltage is used to power up MSM.

The MSM is grounded through the module ground circuit and G300.

### Seat Motors

The MSM controls all seat and lumbar motors via half bridges that are connected to a single power rail internal to the module. The MSM connects all motor outputs on the power rail to a common reference point whenever they are not in operation. This reference point is biased to approximately 2.5 volts. The MSM checks to see if this reference voltage is shorted to ground or battery before enabling any seat or lumbar motor. Refer to Lumbar Support Description and Operation . 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.

There are 4 motors that move the position of the seat. These are the seat horizontal motor, front vertical motor, rear vertical motor and the recline motor. The horizontal motor moves the entire seat forward and rearward. Both vertical motors run simultaneously when the seat switch is operated in order to move the entire seat up and down. Or they can be selected independently to vertically tilt the front or rear of the seat up and down. The recline motor moves the angle of the seat back forward or rearward.

All seat 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 and 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 voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction. All of the seat motors are powered this way.

### Position Sensors

The seat position sensors are potentiometers which are either attached directly to the motor transmission cable or are an internal part of the motor. The memory seat module (MSM) supplies a 5-volt reference through the 5-volt reference circuit and ground through the sensor low reference circuit to the respective seat position sensors. 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 volts. 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 memory function switch from the driver door module that is located on the driver door panel. When a memory switch is pressed, a reduced voltage from a series of resistors is applied through the switch contacts and the memory recall switch signal circuit to the driver door module (DDM). In response to the memory request, the DDM then sends a message to the memory seat module (MSM) via GMLAN serial data line indicating the memory request.

The current seat position may be recorded for 2 different drivers. To record a position, adjust the driver's seat, lumbar support, and both outside mirrors to a comfortable position. Then press and hold the memory 1 button until two beeps sound through the driver's side front speaker. A second seating and mirror 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 and lumbar position sensors for the appropriate driver. Easy exit positions are not programmable; they are pre-programmed to move the entire seat rearward from the seat horizontal position stored in memory for the identified driver.

When a memory recall button is pressed, a single chime is sounded through the driver's side front speaker in order to acknowledge the signal has been received. The MSM then moves the appropriate seat and lumbar motors until the position sensor feedback voltages equal the feedback voltages stored in memory for the identified driver. When the EXIT button is pressed, a single chime is sounded in order to acknowledge the signal. The MSM will then move the entire seat rearward from the current seat horizontal position.

Memory recall operation is disabled if the shift lever is out of NEUTRAL (N) or PARK (P). The memory seat module receives the transmission selector position data via the GMLAN Serial Data circuit.

### Recall Personalization

Refer to the owners manual for the following memory personalization options:

• | Recall upon receipt of the RKE message

• | Recall upon receipt of the remote start feature

• | Easy exit

• | Factory settings

### Memory Inhibit/Enable

The memory seat module (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.