The lumbar support system consists of the following components:

The seat lumbar switch controls the lumbar horizontal and vertical motors located in the seat back through relays that are located under the seat cushion. Battery positive voltage is supplied at all times to the seat lumbar switch from the H SEAT LUM Fuse located in the IP fuse block.

There are two lumbar adjuster relays, horizontal and vertical. Battery positive voltage is supplied at all times to both relays from the SEAT Circuit Breaker located in the IP fuse block. Ground is supplied to both relays through the relay ground circuit and G301. Each relay contains two coils and two sets of switch contacts. With the relay in the inactive or de-energized state, the lumbar motor control circuits are closed to ground through the relay switch contacts and the relay ground circuit.

The lumbar support system consists of two lumbar motors, horizontal and vertical, that operate independently of each other. The horizontal motor moves the lumbar support forward or rearward, and the vertical motor moves the lumbar support up or down. Each motor contains an electronic circuit breaker (PTC), that opens the circuit in the event of a circuit overload and will reset only after the voltage has been removed from the circuit.

Both lumbar motors are reversible. For example, when the lumbar switch is operated to move the lumbar support forward, battery positive voltage is applied through the lumbar switch contacts and the lumbar forward relay control circuit. The relay coil then energizes, causing the forward relay contacts to close to battery positive voltage. Battery positive voltage is then applied through the lumbar motor forward control circuit to the lumbar horizontal motor. The motor is grounded through the lumbar motor rearward control circuit and the rearward relay contacts. The motor then runs to drive the lumbar support forward toward the occupant's back until the switch is released. Moving the lumbar support rearward works similarly to moving the lumbar support forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction. The lumbar vertical motor is also powered this way.