Power Seats

CIRCUIT OPERATION
There are four reversible motors that operate the Power Seats. The front and back height of a seat are operated by different motors. They can be raised or lowered independently of each other. When the FRONT and REAR UP/DOWN switches are pushed simultaneously, both motors run to move the front and rear of the seat at the same time.

Passenger's Seat
The Forward/Back Motor is operated by sliding the Seat Switch forward or backward. When it is held in the FORWARD position, battery voltage from Circuit Breaker 1 (CKT 60) is applied through the Entire Seat Forward Switch contacts to the Forward/Back Motor (CKT 285). The Motor is grounded through CKT 284 and the contacts of the Entire Seat Back Switch to ground G306. The Motor runs to drive the seat forward until the Switch is released.

In the SEAT BACK position, the polarity of the applied voltage is reversed. Battery voltage from Circuit Breaker 1 (CKT 60) is now applied through CKT 284 to the Forward/Back Motor. This reversed polarity causes the Motor to run in the opposite direction and drive the seat backward.

The Front Height, Rear Height and Recliner Motors work in a similar way when their respective switches are operated.

To raise the entire seat, the Front and Rear Up/Down Switches are operated simultaneously. This applies battery voltage to both the Front Height and Rear Height Motors. Both Motors run to drive the entire seat up. A similar action occurs with the reverse polarity to move the entire seat down.

Each Motor contains a self-resetting circuit breaker to protect it from overload.

Driver's Memory Seat
The Driver's Seat operates similarly to the Passenger's Seat for the Power Seat functions, except when the Memory Seat functions are operated. The voltages from the Driver's Seat Switch are first applied to the Seat Memory Module. The Module then operates the appropriate motor(s).

Driver's Recliner Operation
The Seat Memory Module uses an external relay to control the Recliner Motor functions. When the Module receives a RECLINE FORWARD command, battery voltage is applied to terminal C3/D7 (CKT 1025). The Module will output battery voltage through CKT 910 to the Driver's Recliner Relay. This voltage energizes the Relay and applies voltage from Circuit Breaker 1 to terminal A (CKT 276) of the Driver's Recliner Motor. The Motor's ground path is through CKT 277 and the Recliner Relay contacts to 0306. The Recliner Motor runs moving the seat back forward. The recline back function is similar to the recline forward in operation, except the polarities are reversed, causing the motor to run in the opposite direction.

Motor Position Sensors
The Memory Seat System provides an automatic return of the Driver's Seat to one of the two preset positions.

For the Seat Memory Module to remember the seat locations, Position Sensors are utilized. These sensors are potentiometers which are mounted to each motors transmission cable. As the motor transmission cable rotates, the resistance of the potentiometer is varied. The position of the seat is determined by the voltage level sent to the Seat Memory Module by the Position Sensor.

Setting Memory
When using the Set Memory function, the module will beep once with the depression of the SET MEMORY button. This beep lets the user know the Module is ready to receive a memory input. A MEMORY button (1 or 2) must be pressed within five seconds of the depression of the SET MEMORY button. If not, the Module will beep twice. The Module will beep once more if a MEMORY button is pressed within the five second period to acknowledge that the seat position is stored.

Pressing and holding the SET MEMORY button, MEMORY 1 or MEMORY 2 applies battery voltage to terminals C3/D8 (CKT 614), C3/D5 (CKT 615), and C3/C9 (CKT 616), respectively, of the Seat Memory Module. The Seat Memory Module applies a 5 volt signal through CKT 985 to each of the Position Sensors. Depending upon the position of the Motors, the motor position input voltages to the Seat Memory Module varies between 0 and 5 volts. The Module then stores in memory the voltage readings of each position sensor.

Memory Recall
When the MEMORY 1 or 2 button is pressed, battery voltage is applied to terminal C3/D5 (CKT 615) or C3/C9 (CKT 616) of the Module. The Module applies voltage to the Motors until the Position Sensor voltages equal the stored values. The seat will then have returned to the stored position.

Easy Exit
With the Exit Switch closed, voltage is applied through CKT 617 to the Seat Memory Module terminal C3/D11. The module takes this as a signal to move the seat to a full down and full back position. The module applies voltage to all three Seat Motors (the Recliner Motor is excluded from the Easy Exit function) until the seat is fully back and down.

Memory Recall Inhibit/Enable
Although the Power Seat System may be operated with the Ignition Switch in any position, the memory recall functions will only operate if the Gear Selector is in PARK when the Ignition Switch is in RUN.

If the Module sees battery voltage at terminal C3/C12 (CKT 1176) as a result of the Ignition Switch being in RUN, it must also receive battery voltage at terminal C3/C5 (CKT 275) from the Transaxle Range Switch in the PARK position. The purpose for this logic is to prevent the seat from moving to an unsafe position while driving.

Manual Diagnostic Feature
The Seat Memory Module incorporates a manual diagnostic feature that utilizes audible signals. Diagnostics are entered by grounding the Seat Memory Module Diagnostic Connector. Once in the diagnostic mode, the technician can quickly check switch and sensor inputs to the module by listening for certain beeps. See System Diagnosis for more information.