Component Description For Lumbar Support Control Unit - GF91.29-P-5281RF

Model 205, 253 

with code 221 (Electrically adjustable left driver seat) 

with code 222 (Electrically adjustable right driver seat) 

except code 409 (Left and right front multicontour seat) 

Model 205, 253 

with code 242 (Front passenger seat, electrically adjustable with memory function) 

except code 409 (Left and right front multicontour seat) 

Model 205, 253 

with code 275 (Memory Package (driver's seat, steering column and mirror)) 

except code 409 (Left and right front multicontour seat) 

Model 205, 253 

with code P65 (Seat comfort package) 

except code 409 (Left and right front multicontour seat) 

Shown front passenger seat up to 01.03.2018 

Location 

The lumbar support adjustment control units are centrally installed in the respective backrest frame behind the backrest trim.

Tasks 

The lumbar support adjustment control units have the following tasks:

• Control of the air cushion pressure in the lumbar support of the respective seat
• Storage of last adjusted lumbar support contour
• Control of the driver seat lumbar support pneumatic pump (M25/4) or front passenger seat lumbar support pneumatic pump (M25/5)

The tasks are subdivided as follows:

• Reading in of sensors and signals 
• Evaluation of input factors 
• Actuation of components 

Reading in of sensors and signals 

The signals from the following components are read via direct lines:

• Driver seat lumbar support adjustment switch (S109/2)
• Front passenger seat lumbar support adjustment switch (S109/3)
• Internal pressure sensor

Evaluation of input factors 

The read-in input factors are evaluated by the respective lumbar support adjustment control unit. The air cushions in the seat are actuated via valves integrated in the respective lumbar support adjustment control unit.

Actuation of components 

The actuation of the driver seat lumbar support pneumatic pump or front passenger seat lumbar support pneumatic pump for controlling the compressed air supply occurs via a direct line.

The air cushions in the seat are actuated via valves integrated in the respective lumbar support adjustment control unit.

Structure 

The air pressures in the cushions are adjusted by the valves integrated in the respective lumbar support adjustment control unit.

	Wiring diagram for lumbar support control unit	Model 205 as of model year 2019	PE91.29-P-2113-97FBB
		Model 205 up to model year 2019, model 253 (except 253.99)	PE91.29-P-2113-97FBA
		Model 253.99	PE91.29-P-2113-97FCA