Lumbar adjustment function - GF91.29-P-0008RF

Model 205, 253 with code 221 (Electrically adjustable left driver seat) with code 222 (Electrically adjustable right front seat)

Model 205, 253 with code 242 (Front passenger seat, electrically adjustable with memory function)

Model 205, 253 with code 275 (Memory package)

Model 205, 253 with code P65 (Seat comfort package)

Fig 1: Lumbar Adjustment - Block Diagram

Courtesy of MERCEDES-BENZ USA

Function requirements, general

Circuit 15R ON or run-on active
No on-board electrical system limp-home mode
No overvoltage or undervoltage

If circuit 15R is switched off, the lumbar support can still be set for t = 180 s (run-on time). If, during the run-on time, the circuits status or the door status is changed, the run-on time starts again.

Lumbar support adjustment, general

To achieve optimum support of the vertebral column, the backrests on the driver and front passenger seat are each equipped with a lumbar support unit.

The lumbar support unit consists of the following components:

two air cushions
Lumbar support pneumatic pump
Lumbar support adjustment control unit

Function sequence for lumbar support adjustment

Setting is performed via the lumbar support adjustment switch. Pressing of the lumbar support adjustment switch is read in directly by the lumbar support adjustment control unit. The lumbar support adjustment control unit controls the corresponding inflation or deflation of the air cushions via integrated valves. The lumbar support pneumatic pump is directly actuated by the lumbar support adjustment control unit for the compressed air supply.

	Electrical function schematic, lumbar support adjustment		PE91.29-P-2055-97FBA
	Overview of system components, electric seats		GF91.29-P-9992RF