The left and the right power lumbar support systems each consist of the following components:

The lumbar motors operate independently of each other.

The lumbar switches are located on each seat. The lumbar switch directly controls the motors located in the seatback. The PWR SEAT circuit breaker provides power for both seats through the rear junction block. Each motor contains a electronic circuit breaker (PTC) that trips at the end of travel. The circuit breaker resets only after voltage is removed from the motor.

When you push the lumbar switch to the IN position, battery positive voltage (B+) is applied through the IN switch contacts to the lumbar horizontal motor. The motor receives ground through the lumbar OUT switch contacts. The motor then runs in order to drive in the lumbar support away from the occupant's back until one of the following events occur:

The OUT position is similar to the IN position except that the polarity is reversed. The reversed polarity causes the motor to operate in the opposite direction. The lumbar support then moves out toward the occupant's back.

The lumbar vertical motor works in a similar way when the lumbar switch operates in the UP and DOWN positions.

The memory lumbar support system on the left seat consists of the following components:

The MSM controls the movement of the 2 lumbar support motors. The motors operate independently of each other. The MSM contains the following 2 lumbar support motors:

The motors are reversible. For example, the lumbar support moves in and out by one motor. When the MSM receives an input to move the lumbar support in, the MSM supplies the following items:

The lumbar horizontal motor then operates in order to move in the lumbar support in away from the driver's back. When the MSM receives a lumbar out input, the MSM supplies power to the same motor. The MSM switches the voltage and ground to the opposite motor cavities. The voltage polarity reverses and the motor then operates in the opposite direction. The lumbar support moves out toward the driver's back. The lumbar vertical motor operates identically. The MSM supplies voltage to the appropriate lumbar motor when the MSM receives an input from the left lumbar switch.

The MSM provides each lumbar motor with a soft stop. The module stops the motor just before the physical end-of-travel for the motor. The soft stop decreases the stress on the motors. The lumbar support will move a short distance farther to the physical travel limit under the following conditions:

The MSM uses the position sensors in order to perform the following functions:

The MSM provides a 5 volt reference voltage through CKT 788 (GRY). The MSM provides a reference ground through CKT 782 (BLK) to each of the lumbar support position sensors. The sensors are potentiometers mounted to the transmission cable on 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 stores the motor positions by recording each position sensor feedback voltage. When you execute the recall memory command, the module moves the motors until the position sensor feedback voltages equal the feedback voltages stored in memory.

The left front power window switch receives inputs from the memory seat/mirror switch. The left front power window switch then sends a message through the simple bus interface (SBI) to the driver's door module (DDM). The message indicates that the left front power window switch received a memory function input. The DDM then relays the message to the MSM through the class 2 serial data line. The system may record current lumbar support positions for 2 different drivers. Press and hold one of the following buttons for 3 seconds in order to record the current positions:

A chime will sound in order to acknowledge the input. When the MSM receives a memory set message, the MSM records the feedback voltage from the 2 lumbar support position sensors for the appropriate driver.