Lumbar Support Description and Operation (With Memory A45 Disabled)

Lumbar Support Description and Operation (With Memory A45 Disabled)

Lumbar Support Components

The driver seat lumbar support system with a non-memory configured memory seat module (MSM) consists of the following components:

* Lumbar Switch
* Memory seat module (MSM)
* Instrument panel module (IPM)
* Lumbar horizontal motor
* Lumbar vertical motor
* Lumbar horizontal position sensor
* Lumbar vertical position sensor
* DPM Fuse 10 A

The memory seat module (MSM) is also referenced as the driver position module (DPM) for this vehicle.

Non Memory MSM and IPM

The non-memory version of the driver power seat and lumbar still includes the Memory Seat Module (MSM). The RPO codes for seating are A45 for memory and AL2 for lumbar. The instrument panel module (IPM) contains a configuration frame for the vehicle RPOs that is configured according to each vehicle RPO content. In order for the MSM to determine memory configuration, it looks for 2 signals via GMLAN serial data from the IPM to determine seating content. These signals are Memory Seat Present (A45) and Memory Lumbar Present (AL2). When these signals are FALSE, the seat is non-memory and the MSM will not look for inputs from the seat position sensors. However, the MSM always looks for column position sensor inputs. Refer to Steering Wheel and Column Description and Operation (Description and Operation).

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 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 a positive temperature coefficient (PTC) circuit breaker 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 (Description and Operation).

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.

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.