Electrical seat adjustment (ESA) - GF91.29-P-0009RFA

MODEL 205, 253 without CODE 221 (Electrically adjustable left driver seat) without CODE 222 (Electrically adjustable right front seat) without CODE 275 (Memory package)

Fig 1: Electrical Seat Adjustment (ESA) - Block Diagram

Courtesy of MERCEDES-BENZ USA

Function requirements, general

Circuit 15R ON or run-on active
No overvoltage or undervoltage

If circuit 15R is switched off, the electric seats 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.

The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN to the rear SAM control unit.

Electrical seat adjustment (ESA), general

The ESA enables the electrical adjustment of the driver and front passenger seat. The driver and front passenger seat can be adjusted as follows:

Seat height
Backrest inclination
Seat inclination (with CODE P65 (Seating comfort package))

The ESA function comprises the following subfunctions:

Function sequence for manual seat adjustment
Function sequence for antilock device

Function sequence for manual seat adjustment

For manual seat adjustment, the following switches must be pressed and held until the required position is reached:

Driver seat partially electric seat adjustment switch
Front passenger seat partially electric seat adjustment switch

Following this, the corresponding seat adjustment motor is actuated:

Seat adjustment motor for backrest inclination, driver seat or front passenger seat
Driver or front passenger seat inclination adjustment seat adjustment motor (with CODE P65 (Seating comfort package))
Seat adjustment motor for seat height adjustment, driver seat or front passenger seat

The power for the seat adjustment motors is supplied by the rear SAM control unit directly via the respective partially electric seat adjustment switch.

Function sequence for antilock device

Since the electrical seat adjustment does not have a sensor system or its own control unit, the anti-lock protection occurs by means of a thermal fuse in the seat adjustment motors. As a result, if the respective seat adjustment motor is blocked, it is not switched off until it exceeds a certain temperature threshold.

	Electrical function schematic for seat adjustment (ESA)		PE91.29-P-2059-97FBB
	Overview of system components, electric seats		GF91.29-P-9992RF