Lumbar Support Description and Operation with A45

The driver seat lumbar support system with memory (A45) consists of the following components:

Battery positive voltage is supplied at all times to the driver seat lumbar switch from the MEM Fuse located in the rear fuse block. When the lumbar switches are pressed they send a 12 volt signal to the MSM. The MSM then commands the lumbar motors to move in response to the switch signals.

The lumbar support system consists of two motors (horizontal and vertical) that operate independently of each other. The lumbar horizontal motor moves the lumbar support in the forward or rearward directions while the lumbar vertical motor moves the lumbar support in the up or down directions. Each motor contains a electronic circuit breaker (PTC) that opens in the event of a circuit overload and will reset only after voltage has been removed from the circuit. The memory seat module 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 it's physical travel limit.

When the lumbar switch is operated to move the lumbar support forward, battery positive voltage is applied through the switch contacts and the driver seat lumbar forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery positive voltage through the lumbar motor forward control circuit and ground through the 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 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, battery positive voltage is applied through the switch contacts and the driver seat lumbar up switch signal circuit to the MSM. In response to this signal, the MSM applies battery positive voltage through the lumbar motor up control circuit and ground through the 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 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 each lumbar position sensor. When the lumbar motor rotates, the resistance of the potentiometer varies changing the feedback voltage of the position sensor signal circuit. This voltage varies from 0.25-4.75 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 .

Lumbar Support Description and Operation w/o Memory-A45

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

Battery positive voltage (B+) is supplied at all times to the driver and passenger seat lumbar switches from the PWR SEAT Circuit Breaker located in the rear fuse block. Battery positive voltage (B+) is supplied at all times to the LR and RR passenger lumbar switches from the RR LUM/ANT Fuse located in the rear fuse block. All four lumbar switches are grounded through the switch ground circuits and G 302. The lumbar switches provide both power and ground to the selected lumbar motors.

The lumbar support system consists of two lumbar motors (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 forward and rearward and the lumbar vertical motor moves the lumbar support up and down.

When the lumbar switch is operated to move the lumbar support rearward, battery positive voltage (B+) is applied through the lumbar rearward switch contacts and the lumbar motor rearward control circuit to the lumbar horizontal motor. The motor is grounded through the lumbar forward switch contacts and the lumbar motor forward control circuit to the horizontal motor. The motor runs to drive the lumbar support rearward away from the occupant's back until the switch is released. Moving the lumbar support forward works similarly to moving the lumbar support rearward, 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 up, battery positive voltage (B+) is applied through the lumbar up switch contacts and the lumbar motor up control circuit to the lumbar vertical motor. The motor is grounded through the lumbar down switch contacts and the lumbar motor down control circuit to the vertical 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 AC9

The driver and passenger adaptive seat systems each consist of the following components:

This is a power inflate/deflate pneumatic system used for controlling seat comfort by inflating or deflating an air cell within the seat cushion or seat back. The adaptive seat system will operate only when the ignition switch is in the ON position.

Battery positive voltage is supplied at all times to the driver and passenger adaptive lumbar modules through the battery positive voltage circuit and the MEM T&T Fuse located in the rear fuse block. Battery positive voltage is also supplied to the adaptive lumbar modules through the ignition 3 voltage circuit and the IGN 3 Fuse located in the rear fuse block. Both, the driver and passenger adaptive lumbar modules are grounded through the module ground circuit and G302. Battery positive voltage is supplied to the lumbar switch through the battery positive voltage circuit and the adaptive lumbar module.

The lumbar support in the seat back may be adjusted manually. When the lumbar forward switch is operated to move the lumbar support forward and increase the amount of lumbar support, battery positive voltage is applied through the switch contacts and the lumbar forward signal circuit to the adaptive lumbar module. In response to this signal, the adaptive lumbar module applies battery voltage to the lumbar pump motor. The motor runs to inflate the lumbar bladder in the seat back until the switch is released. When the lumbar rearward switch is operated to move the lumbar rearward and decrease the amount of lumbar support, battery positive voltage is applied through the switch contacts and the lumbar rearward signal circuit to the module. In response to this signal, the module releases air from the lumbar support bladder until the switch is released.

At the beginning of 2001 model year production, the driver and passenger adaptive seat feature would automatically activate with the cycle of the ignition switch to the ON position. During production the feature was changed from automatic activation to manual activation.

To manually activate the adaptive seat feature, momentarily press the lumbar switch where it is marked AUTO/ON. When the AUTO/ON switch is pressed, battery positive voltage is applied through the switch contacts and the adaptive seat switch auto/on signal circuit to the adaptive lumbar module. In response to this signal, the module will inflate the seat bladders as described in manual control, take a reading, then automatically adjust the comfort level to the occupant by releasing air from the bladders or adding air to the bladders when needed. The adaptive lumbar module will check the position of the occupant every 4 minutes. If the occupant has moved, the adaptive lumbar module will then automatically adjust the amount of air to the new position of the occupant. If the adaptive function is not desired, the driver or passenger must manually deactivate or turn off the system. The system is turned off by pressing the lumbar switch down to the off position. Battery positive voltage is then applied through the switch contacts and the adaptive seat off switch signal circuit to the module. In response to this signal, the adaptive lumbar module will release all air from the bladders.