For 1990-2009 cars

### Memory Seat System Components

The memory seat system consists of the following components:

• | Memory seat module

• | Memory seat adjuster switch

• | Seat adjuster switch

• | Seat horizontal motor/sensor

• | Seat front vertical motor/sensor

• | Seat rear vertical motor/sensor

• | Seat recline motor/sensor

• | F13DA 25 A fuse

• | F19DA 5 A fuse

### Power Seat Switches

Ground is supplied at all times to the seat adjuster switch from G305. The memory seat module supplies a reference voltage to each signal circuit of the seat adjuster switch. When the power seat switches are pressed, the appropriate signal circuit from the memory seat module is pulled low through the switch contacts indicating the power seat command. The memory seat module then commands the driver seat to move in response to the switch signals.

### Seat Motors

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 seat back 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.

The memory seat module controls all seat motors via half bridges that are connected to a single power rail internal to the module. The module 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 memory seat module checks to see if this reference voltage is shorted to ground or battery before enabling any seat motor. All seat 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 seat motors are reversible. For example, when a seat switch is pressed to move the entire seat forward, ground is applied through the switch contacts and seat horizontal forward switch signal circuit to the memory seat module. In response to this signal, the memory seat module 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.

### Seat Position Sensors

The seat motors are equipped with 2 wire hall effect type position sensors internal to the motor. The sensors are monitored by the memory seat module and are used to determine seat positions when storing or recalling memory settings. The memory seat module supplies the sensors with a commom 12 V reference circuit and separate signal circuits. During seat motor operation, the hall effect position sensor provides a determined number of pulse signals for every revolution of the motor shaft. These pulse signals (Counts) range from 0 - 65,535. High scan tool count values indicate forward or upward seat positions while low count values indicate rearward or downward seat positions.

### Memory Functions

Ground from the memory seat module is supplied at all times through the low reference circuit to the memory seat adjuster switch. The module also supplies memory set and memory recall signal circuits to the memory seat adjuster switch.

Seat positions may be recorded for 2 different drivers. To record the current seat position for driver 1, adjust the driver's seat and the exteriors mirrors to a comfortable position. Press and hold the MEM button, then press button 1 and a singal chime will sound indicating the memory position is set. A second seating position may be programmed by repeating the above steps and pressing button 2 for driver 2. When the memory seat module receives a memory set message, it records the counts from the seat position sensors for the appropriate driver.

Memory recalls via the memory switch are supervised operations. This requieres the driver to press and hold the memory button until the seat reaches it's memory position. When a memory switch is pressed, the signal circuit from the memory seat module is pulled low through a series of resistors and the switch contacts indicating the memory recall request. In response to this signal, the module applies battery voltage to run the appropriate seat motors until the position sensor counts equal the counts stored in memory for the appropriate driver.

### Keyless Entry and Memory Recall Personalization

When a keyless entry transmitter is used in order to unlock the vehicle's doors, the body control module communicates the unlock command and which driver performed the command to the memory seat module via a serial data message. Vehicle lock/unlock functions and memory recall settings may be personalized. For functional descriptions and personalization instructions, refer to the vehicle owners manual.