The memory seat system consists of the following components:

These motors have a position sensor attached to each motor.

The MSM controls the movement of the 3 seat position motors. The MSM controls one seat back recline motor. All of the motors operate independently of each other.

In order to power the MSM, the rear compartment fuse block BATT fuse through CKT 1840 (ORN) supplies battery positive voltage (B+). The left underhood fuse block SEAT circuit breaker through CKT 742 (RED) provides battery positive voltage (B+) to the MSM which is used in order to run the seat motors. The MSM grounds through CKT 850 (BLK) to G302.

The following 3 motors move the position of the seat:

Both vertical motors run simultaneously when the left seat switch signals the entire seat to move up or down. The recline motor moves the angle of the seat back. The headrest motor moves the height of the headrest.

All of the motors are reversible. For example, one motor moves the seat both forward and back. When the seat switch sends a signal to the MSM in order to move the seat forward, the MSM supplies the battery positive voltage (B+) and ground in order to run the motor and move the seat forward:

When the seat switch sends a signal to the MSM in order to move the seat back, the MSM supplies power to the same motor. The voltage and the ground apply to the opposite cavities on the motor connector. The following events occur in order to move the seat back:

All of the following motors run in an identical manner:

The MSM provides each seat motor with a soft stop. The module stops the motor just before the end of travel for the seat. The soft stop decreases the stress on each motor. If the following conditions occur, the seat moves a short distance farther to the physical travel limit:

The memory seat module (MSM) uses the position sensors in order to perform the following functions:

The MSM provides a 5 volt reference voltage through CKT 788 (GRY) and the reference ground through CKT 782 (BLK) to each of the following components:

The position sensors are potentiometers mounted to the transmission cable of each motor. When the cable rotates, the resistance of the potentiometer varies. The MSM monitors the feedback voltage of the potentiometer in order to determine the position of the motor. The sensor feedback voltages vary from 0.25 volts to 4.75 volts. When you execute a set memory command, the MSM records each position feedback sensor in order to store the motor positions. When you command a memory recall, the MSM moves the motors until the feedback voltages of all of the position sensors equal the feedback voltages stored in memory.

For the easy exit functions, the MSM records only the seat position sensor feedback voltages. Only the seat motors run during the easy exit function.

For the Eldorado, the memory seat module (MSM) receives the manual movement inputs of the seat from the left seat switch. When the MSM receives one of the following inputs, the MSM supplies battery positive voltage (B+) to the appropriate motor(s) and the seat moves accordingly:

For the DeVille, the memory mirror module (MMM) receives the seat manual movement inputs from the left seat switch. The MMM then sends a Class 2 message to the memory seat module (MSM), informing the MSM of the seat switch activation.

The MSM supplies battery positive voltage (B+) to the following appropriate motors that cause seat movement:

The memory mirror module (MMM) receives the seat manual movement inputs from the memory function switch.

The following may be recorded for 2 different drivers

In order to record the current seat positions, press and hold one of the following buttons for 5 seconds:

When the MMM receives these inputs, the MMM records the feedback voltages from the 4 mirror position sensors for the appropriate driver. A chime sounds in order to acknowledge the input. A Class 2 message to the memory seat module (MSM) is also sent informing of the SET MEMORY command. When the MSM receives a memory set message, the MSM records the feedback voltages from the following sensors for the appropriate driver:

An easy exit position for each driver may also be recorded. In order to perform this function, move the seat to a comfortable exit position. Press the SET MEMORY button, which is followed by a chime to acknowledge the input. Within 5 seconds, the EXIT button is pressed. The MMM identifies the driver for the last recall or set command. This identification informs the MSM of the set exit command. The proper driver is then recorded through a Class 2 message.

The MSM records the following feedback voltages for the appropriate drivers:

In order to acknowledge that the position was recorded, a single chime is sounded. For diagnosis of the memory function switch, refer to Outside Rearview Mirror Schematics in Doors.

When the MEMORY-1 or the MEMORY-2 is pressed, the memory mirror module (MMM) receives this input. A chime sounds. The MMM applies battery positive voltage (B+) to the mirror motors until all of the mirror position sensor feedback voltages equal the voltages stored in memory for the appropriate driver.

In order to perform the memory recall function through a Class 2 message, the memory seat module (MSM) receives a command. The MSM applies battery positive voltage (B+) to all of the seat and the lumbar motors until the position sensor feedback voltages equal the voltages stored in memory for the appropriate driver.

The easy exit seat position can be recalled by pressing the EXIT button. A single chime sounds. The MMM identifies the driver for the last recall or set command. This identification informs the MSM of the exit recall command/driver identification through a Class 2 message.

The MSM moves the following motors until the position sensor feedback voltages equal the voltages stored in memory for the appropriate driver:

For diagnosis of the memory function switch, refer to Outside Rearview Mirror Schematics in Doors.

When you use a keyless entry transmitter in order to unlock the doors of the vehicle, the remote function actuator (RFA) module communicates the following information to the memory seat module (MSM) through a Class 2 message:

The following 3 personalized recall options are available when the MSM receives an unlock command:

The memory mirror module (MMM) receives the park gear and the ignition inputs through the Class 2 messages.

When the ignition switch is OFF, the following functions are allowed:

The personalization recall function deactivates under the following conditions:

All of the other memory functions remain operative.

The memory record remains active under the following conditions:

All of the other memory functions deactivate.

The memory seat module (MSM) incorporates diagnostic features that use audible sounds heard through the radio speakers. The diagnostic mode is entered by grounding the MSM diagnostic connector. The module is taped to the body harness.

In order to acknowledge entry into the diagnostic Mode 1, the MSM sounds one chime. The MSM diagnostic connector must remain grounded during testing. For Mode 1, all of the seat switch inputs are tested with the seat movement disabled. For each switch that is activated, one chime sounds. The MSM did not acknowledge the input if a switch is activated with no chime.

In order to acknowledge entry into the diagnostic Mode 2 diagnostics, remove the ground from the MSM diagnostic connector. This action must be done within 5 seconds. All of the position sensors are tested for a gradual voltage change in Mode 2. The seats move. A chime sounds for any large change in feedback voltage, or no change at all.

There may be concern with the position sensor in the direction the seat switch is operated. The MSM does not acknowledge a problem with the position sensors if a chime is not heard in Mode 2. In order to exit the diagnostic mode, remove the ground for more than 5 seconds. In order to acknowledge exit of the diagnostic Mode, 3 chimes sound.