Optional Lumbar Support

Optional Seat Back Lumbar Support

The optional air bladder lumbar support system is similar to the E38/E39 comfort seat. Each seat contains the following components:
- Four position circular rocker switch in the seat base trim in the area of the seat switches.
- Electrically controlled air compressor with over pressure cut out under each seat.
- Two solenoid activated air controlling valve blocks (one per air bladder). Each valve block includes an inlet and an outlet valve. When energized they direct air into the bladder(s) to inflate or relieve trapped air to deflate the bladders.
- Connecting hoses and air bladders in lower seat back

Operation







The lumbar support system can be operated at any time regardless of key position. The four position circular rocker switch provides power switching to operate the system as follows:
- Position 1: The internal switch contacts provide a power and ground path for both valve block inlet valves and the air compressor. Both bladders inflate until the switch is released. If the switch is held continuously, an overpressure bypass valve opens on the compressor preventing damage to the bladders.
- Position 2: Compressor activated, upper bladder inflates, lower bladder deflates
- Position 3: Compressor activated, lower bladder inflates, upper bladder deflates
- Position 4: Compressor is not activated. Upper and Lower bladders both deflate.

Diagnosis

The seat lumbar support system is purely electro-pneumatic control system. No electronic diagnostic communication is possible.