Lumbar Support (With Memory A45)

Lumbar Support Description and Operation (With Memory A45)

Lumbar Support Components

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

* Lumbar switch

* Seat memory control module

* Seat lumbar support module

* Seat upper lumbar motor

* Seat lower lumbar motor

Lumbar Switch

Ground is supplied at all times to the driver seat lumbar support switch through the switch ground circuit and ground connection. The seat memory control module supplies a low current voltage to each signal circuit of the seat lumbar support switch. When the seat switches are pressed, the appropriate signal circuit from the seat memory control module is pulled low through the switch contacts indicating the lumbar command. The seat memory control module then commands the lumbar support to move in response to the switch signals.

Motors

The lumbar support system consists of 2 horizontal motors 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 upper horizontal motor moves the upper lumbar support in the forward or rearward directions while the lumbar lower horizontal motor moves the lower lumbar support in the forward and rearward directions. The seat memory control module controls both lumbar motors via half bridges that are connected to a single power rail internal to the module. The module connects all lumbar motor outputs on the power rail to a common reference point whenever they are not in operation. This reference point is biased to approximately 2.5 volts. The module checks to see if this reference voltage is shorted to ground or battery before enabling any seat or lumbar motor.

Lumbar Description of Operation

The lumbar support is a dual zone mechanical lumbar system that is designed to move the lumbar support either forward, rearward, up, or down. The system has 2 motors and a lumbar control module that is used to direct power to the motors to accomplish the following functions:

* When the lumbar forward switch is pressed, both lumbar motors are activated to move the upper and lower lumbar support forward.

* When the lumbar rearward switch is pressed, both lumbar motors are activated to move the upper and lower lumbar support rearward.

* When the lumbar up switch is pressed, the upper lumbar motor is activated to move the upper lumbar forward while the lower lumbar motor is activated to move the lower lumbar rearward.

* When the lumbar down switch is pressed, the lower lumbar motor is activated to move the lower lumbar support forward while the upper lumbar motor is activated to move the upper lumbar support rearward.

Circuit Description

Ground is supplied to the driver seat adjuster switch through the switch ground circuit and G305. The seat memory control module supplies a low current voltage to each signal circuit of the seat adjuster switch. When the lumbar switches are pressed, the appropriate signal circuit is pulled low through the switch contacts indicating the lumbar support command. The seat memory control module then commands the appropriate lumbar support motor to move in response to the switch signal as described below.

* Lumbar Forward/Rearward - When the lumbar forward switch is pressed, the lumbar forward signal circuit is pulled low indicating the lumbar support forward command. In response to this signal, the seat memory control module applies battery voltage through the lumbar forward control circuit and ground through the lumbar rearward control circuit to the lumbar support module. The power and ground is then directed through the module and the lumbar control circuits to both the upper and lower lumbar support motors. Both motors run to drive the lumbar support forward towards 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 voltage and ground are applied on opposite circuits causing the motors to run in the opposite direction.

* Lumbar Up - When the lumbar up switch is pressed, the lumbar up signal circuit from the seat memory control module is pulled low indicating the lumbar up command. In response to this signal, the seat memory control module applies battery voltage through the lumbar up control circuit and ground through the lumbar down control circuit to the lumbar support module. The lumbar support module directs this voltage through the upper lumbar forward control circuit and ground through the upper lumbar rearward control circuit to the upper lumbar support motor. The motor runs to drive the upper lumbar support forward toward the occupant's back. At the same time, the lumbar support module directs the voltage through the lower lumbar rearward control circuit and ground through the lower lumbar forward control circuit to the lower lumbar support motor. The motor runs to move the lower lumbar support rearward away from the occupant's back.

* Lumbar Down - When the lumbar down switch is pressed, the lumbar down signal circuit from the seat memory control module is pulled low indicating the lumbar down command. In response to this signal, the seat memory control module applies battery voltage through the lumbar down control circuit and ground through the lumbar up control circuit to the lumbar support module. The lumbar support module directs this voltage through the lower lumbar forward control circuit and ground through the lower lumbar rearward control circuit to the lower lumbar support motor. The motor runs to drive the lower lumbar support forward toward the occupant's back. At the same time, the lumbar support module directs the voltage through the upper lumbar rearward control circuit and ground through the upper lumbar forward control circuit to the upper lumbar support motor. The motor runs to move the upper lumbar support rearward away from the occupant's back.