For 1990-2009 cars

## Power Seats System Description and Operation without A45

The passenger power seat system consists of the following components:

• | Seat Adjuster Switch

• | Seat Horizontal Motor

• | Seat Front Vertical Motor

• | Seat Rear Vertical Motor

• | Seat Recline Motor

• | SEATS Circuit Breaker 30 A

### Seat Adjuster Switch

The seat adjuster switches provide both power and ground to the selected seat motors. Battery positive voltage is supplied at all times to the passenger seat adjuster switches from the SEATS Circuit Breaker located in instrument panel fuse block. Both seat adjuster switches are grounded through the switch ground circuit and G30.

### Motor

All of the seat motors operate independently of each other. Each motor contains an electronic circuit breaker (PTC). It opens in the event of a circuit overload and will reset only after voltage has been removed from the circuit. There are 4 seat position motors. These are the horizontal motor, front vertical motor, rear vertical motor, and the seat back recline motor. The horizontal motor moves the entire seat forward and rearward. The seat vertical motors may operate independently to tilt the front or rear of the seat cushion up or down. Both motors can also run simultaneously to move the entire seat up or down. The recline motor moves the angle of the seat back forward or rearward.

### Horizontal

When the seat switch is operated to move the entire seat forward, battery positive voltage is applied through the switch contacts and the horizontal motor forward control circuit to the motor. The motor is grounded through the horizontal motor rearward switch contacts and the horizontal motor rearward control circuit to the motor. The motor runs in order to drive the entire seat forward until the switch is released. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

### Rear Vertical

When the seat switch is operated to tilt the rear of the seat cushion up, battery positive voltage is applied through the switch contacts and the rear vertical motor up control circuit to the rear vertical motor. The motor is grounded through the down switch contacts and the rear vertical motor down control circuit to the motor. The motor runs in order to drive the rear of seat cushion up until the switch is released. Tilting the rear of the seat cushion down works similarly to tilting the rear of the seat cushion up, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

### Front Vertical

When the seat switch is operated to tilt the front of the seat cushion up, battery positive voltage is applied through the switch contacts and the front vertical motor up control circuit to the motor. The motor is grounded through the down switch contacts and the front vertical motor down control circuit to the motor. The motor runs in order to drive the front of seat cushion up until the switch is released. Tilting the front of the seat cushion down works similarly to tilting the front of the seat cushion up, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

### Entire Seat Up or Down

When the seat switch is operated in order to move the entire seat to the up position, battery positive voltage is simultaneously applied through the front and rear vertical motor up switch contacts and the front and rear vertical motor up control circuits to both vertical motors. The motors are grounded through the down switch contacts and the front and rear vertical motor down control circuit to both vertical motors. Both motor runs simultaneously in order to drive the entire seat up until the switch is released. Moving the entire seat down works similarly to moving the entire seat up, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

### Recline

When the seat recline switch is operated to move the seat back forward, battery positive voltage is applied through the switch contacts and the recline motor forward control circuit to the motor. The motor is grounded through the rearward switch contacts and the recline motor rearward control circuit to the motor. The motor runs in order to drive the seat back forward until the switch is released. Moving the seat back rearward works similarly to moving the seat back forward, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

## Power Seats System Description and Operation with A45 Disabled

The driver power seat system with a non-memory configured memory seat module (MSM) consists of the following components:

• | Memory Seat Module

• | Seat Adjuster Switch

• | Seat Horizontal Motor

• | Seat Front Vertical Motor

• | Seat Rear Vertical Motor

• | Seat Recline Motor

• | PWR Seat Circuit Breaker 30 A

• | MEM T&T Fuse 10 A

### Non Memory Driver Memory Seat Module and IPM

The non memory version of the driver power seat still includes the memory seat module (MSM). The RPO codes for seating are A45 for memory and AL2 for lumbar. The instrument panel module (IPM) contains a configuration frame for the vehicle RPOsand is configured according to RPO content. In order for the MSM to determine the memory configuration it looks for 2 signals, via GMLAN, from the IPM to determine the seating RPO content. These signals are Memory Seat Present (A45) and Memory Lumbar Present (AL2). When these signals are FALSE, the seat is non memory, and the MSM will not receive signals from the seat position sensors. However, the MSM controls the steering column, it still receives signals from the column position sensor. Refer to Steering Wheel and Column Description and Operation.

### Seat Adjuster Switch

Battery positive voltage is supplied at all times to the seat adjuster switch from the MEM T& T Fuse located in the rear fuse block. When the power seat switches are pressed they send a 12 volt signal to the memory seat module (MSM). The MSM commands the selected seat motor to move in response to the switch inputs.

### MSM Power and Grounds

Battery positive voltage is supplied at all times to the memory seat module (MSM) from the PWR SEAT Circuit Breaker located in the rear fuse block. This voltage is used to power up MSM and also to apply power to the seat motors when commanded. Battery positive is also supplied to the MSM from the MEM T&T Fuse located in the rear fuse block. The MSM monitors this voltage to determine the state of power at seat adjuster switch. If voltage is not detected from this circuit, the MSM will cancel or disable all memory recall functions. Ground is provided to the module through the ground circuit and G 307.

### Seat Motors

The memory seat module (MSM) controls the movement for each of the seat directional motors and the 2 lumbar motors. 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 seat horizontal motor, front vertical motor, rear vertical motor, and recline motor. The horizontal motor moves the entire seat forward and rearward. Both vertical motors can 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 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 positive voltage is applied through the seat horizontal forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery positive 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 opposite circuits causing the motor to run in the opposite direction. All of the seat motors are powered in this way.

Soft stop functions are not used for driver seat motors that are controlled by either a memory or non-memory MSM. However, soft stop functions are used for the MSM controlled steering column motors. Refer to Steering Wheel and Column Description and Operation.