Lumbar Support Description and Operation w/o A45

The driver and passenger lumbar support systems each consist of the following components:

The seat lumbar switches control the lumbar horizontal and vertical motors located in the seat back through the lumbar horizontal and vertical relays located under the seat cushion. Battery positive voltage (B+) is supplied at all times to the driver and passenger seat lumbar switches through the battery positive voltage (B+) circuit and the BATT Fuse located in the rear fuse block. Battery positive voltage (B+) is also supplied at all times to each lumbar relay through the battery positive voltage circuit and the SEATS Circuit Breaker located in the left underhood fuse block.

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

When the lumbar switch is operated to move the lumbar support to the forward position, battery positive voltage (B+) is applied through the switch contacts and the seat lumbar forward relay control circuit to the forward coil in the lumbar vertical relay. The coil energizes causing the forward contacts to close. Battery positive voltage (B+) is then applied through the seat lumbar motor forward control circuit to the motor. The motor is grounded through the lumbar relay rearward switch contacts and the seat lumbar motor rearward control circuit to the motor. The motor 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 (B+) and ground are applied on opposite circuits causing the motor to run in the opposite direction.

When the lumbar switch is operated to move the lumbar support to the UP position, battery positive voltage (B+) is applied through the switch contacts and the seat lumbar up relay control circuit to the up coil in the lumbar vertical relay. The relay coil energizes causing the up contacts to close. Battery positive voltage (B+) is then applied through the seat lumbar motor up control circuit to the motor. The motor is grounded via the lumbar relay down switch contacts and the seat lumbar motor down control circuit to the motor. The motor runs to drive the lumbar support up until the switch is released. Moving the lumbar support down works similarly to moving the lumbar support up, except that battery positive voltage (B+) and ground are applied on opposite circuits causing the motor to run in the opposite direction.

Lumbar Support Description and Operation with A45

The driver memory lumbar support system consists of the following components:

The lumbar switch is grounded via the switch ground circuit and G302. When the switch is operated to adjust the lumbar position, the switch provides the selected lumbar signal circuit from the MSM a path to ground. The MSM commands the lumbar motor to move in response to the switch input.

The lumbar support system consists of two motors (horizontal and vertical) that 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. The lumbar vertical motor moves the lumbar support in the up and down directions. The lumbar horizontal motor moves the lumbar support in the forward and rearward directions. The MSM provides each motor with a soft stop that will actually stop the motor just before its physical end-of-travel. This decreases the stress on each motor. If a motor reaches the end-of-travel due a soft stop and the switch is released and pressed again, the lumbar support will move short distance farther to the physical travel limit.

When the lumbar switch is operated to move the lumbar support forward, the lumbar forward switch signal circuit of the MSM is pulled low through the lumbar switch contacts and ground. In response to this signal, the MSM applies battery positive voltage (B+) through the lumbar forward control circuit and ground through the lumbar rearward control circuit to the motor. The motor 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 (B+) and ground are applied on the opposite circuits causing the motor to run in the opposite direction. The MSM also controls the lumbar horizontal motor during memory recall functions.

When the lumbar switch is operated to move the lumbar support up, the lumbar forward switch signal circuit of the MSM is pulled low through the lumbar switch contacts and ground. In response to this signal, the MSM applies battery positive voltage (B+) through the lumbar up control circuit and ground through the lumbar down control circuit to the motor. The motor runs to drive the lumbar support up until the switch is released. Moving the lumbar support down works similarly to moving the lumbar support up except that battery positive voltage (B+) and ground are applied on the opposite circuits causing the motor to run in the opposite direction. The MSM also controls the lumbar vertical motor during memory recall functions.

The lumbar position sensors are potentiometers which are attached directly to each lumbar motor. The MSM supplies a 5 volt reference voltage through the 5 volt reference circuit and ground through the low reference circuit to the respective lumbar position sensors. When the motor rotates, the resistance of the potentiometer varies changing the feedback voltage of the position sensor signal circuit. The voltage varies from 0.25 volts to 4.75 volts. The MSM monitors this voltage signal to determine the lumbar position. When a memory set command is received, the MSM records the lumbar position by storing the feedback voltage from each position sensor. Then, when a memory recall command is received, the MSM moves the motors until the position sensor feedback voltages equals the feedback voltages stored in memory. The lumbar support is not involved in the easy exit function.

Refer to Memory Seats Description and Operation