Front Lumbar Support

Using lumbar support, the backrest can be individually adapted to the spinal column and thus ensures relaxed driving. Lumbar support is a standard feature in the multifunction seat.

The button for the lumbar support adjustment is located on the side of the front seat and is connected via the LIN bus to the seat module. The function of the lumbar support is integrated completely in the seat module. The lumbar support is adjustable from terminal 30B ON.

Fig 1: Identifying Seat Adjustment Switches And Lumbar Support Switch

Courtesy of BMW OF NORTH AMERICA, INC.

COMPONENTS DESCRIPTION CHART

Index	Explanation
1	Button for lumbar-support adjustment
4	Backrest inclination and head restraint adjustment
5	Longitudinal seat, seat-height and seat inclination adjustment

The seat module requests the button status for the lumbar support adjustment via the LIN bus an on a cyclical basis. Lumbar support is provided by two inflatable air cushions in the backrest. The desired air cushion is inflated with air or deflated via two solenoid valves until such time that the button for the lumbar-support adjustment is released.

The pump for lumbar-support adjustment delivers the required air pressure. The pump and the solenoid valves are activated from the seat module.

NOTE: Seats with the lumbar support option are generally fitted with a seat module. For this reason, all seat heating or seat adjustment functions are located in the seat module.
The seat adjustment switches are read in from the seat module via the LIN bus.