Lumbar Support (With RPO Code A45 Enabled)

LUMBAR SUPPORT DESCRIPTION AND OPERATION (WITH RPO CODE A45 ENABLED)

LUMBAR SUPPORT COMPONENTS
The driver seat lumbar support system with memory (A45) consists of the following components:
- Lumbar switch
- Memory seat module (MSM)
- Lumbar horizontal motor
- Lumbar vertical motor
- Lumbar horizontal position sensor
- Lumbar vertical position sensor
- DPM Fuse 10 A

The memory seat module (MSM) is referenced in the Tech 2 as the driver position module (DPM).

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

MOTORS
The lumbar support system consists of 2 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 an 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.

Soft stop functions are not used for driver seat motors that are controlled by either a memory or non-memory MSM. However, soft stop functions are used for the MSM controlled steering column motors. Refer to Steering Wheel and Column Description and Operation in Steering Wheel and Column.

LUMBAR HORIZONTAL MOVEMENT
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.

LUMBAR VERTICAL MOVEMENT
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.

LUMBAR POSITION SENSORS
The lumbar position sensors are potentiometers which are an internal part of 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.

MEMORY FUNCTIONS
Refer to Memory Seats Description and Operation .