Lumbar support drive and valve block

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2017 BMW X3, 2016 BMW X3, 2015 BMW X3, 2014 BMW X3, and 2013 BMW X3. However, it is still accessible from the selected car via links, so may be relevant.

The lumbar support in the backrest comprises 2 inflatable lumbar support cushions. The lumbar supports overlap in some areas. An electro-pneumatic pump (called: lumbar support pump) supplies the lumbar supports with compressed air. The desired setting for the lumbar support is controlled using the button for the lumbar-support adjustment.

The button signals are not evaluated in the seat module, but by the evaluation electronics in the valve block for the lumbar support. The evaluation electronics activate the lumbar support pump and the solenoid valves in the valve block for the lumbar support. The individual lumbar support cushions are filled or emptied via the valve block for the lumbar support. The lumbar support can thereby be adjusted to the desired height and stiffness.

A pressure relief valve in the valve block for the lumbar support protects the system against excessive system pressure.

Fig 1: Identifying Lumbar Support Valve Block

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Valve block for lumbar support
2	Valve block for backrest width adjustment
3	Lumbar support pump (electro-pneumatic pump)