Electric seat adjustment with memory, function - GF91.29-P-0002F

MODEL 210 with CODE (241) memory circuit for left front power seat with CODE (242a) memory circuit for right front power seat

Fig 1: Identifying Electric Seat Adjustment With Memory, Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The power seat with memory can be controlled with switch unit (S91, S92).

Seat adjustment:

Turn key in ignition lock to position 1 or 2 (when one of the front doors is open also with ignition key removed or in key position 0).

The head restraint height is adjusted automatically when the seat is adjusted so that the rear of the head is supported at approximately ear height.

If this position is not achieved automatically, adjust the head restraint with the switch (S91s4/S92s4) in the door.

The inclination of the head restraint can be adjusted manually.

Power front seat

Injury hazard!

Seat positions, which negatively affect the course of the seat belt pose a safety hazard and must therefore be avoided under all circumstances.

The backrest should be nearly upright. The back should make contact with the backrest and the seat belt in the area of the shoulder.

Accident hazard!

When adjusting the seat ensure that no one can be pinched.

Remove the key from the steering wheel lock even when leaving the vehicle for a short time.

For safety reasons adjust the seat only with the vehicle standing still.

Control modules

The "Front power seat control modules with memory (N32/1 and N32/2)" control

five seat adjustment functions.
transfer of the switch signals for the steering column adjustment S91s11/S91s12 (LHS), S92s11/S92s12 (RHS) via the internal bus (I-bus) to the multi-function control module (N10). From the multifunction control module (N10) the signal travels to the motors for adjustment of the steering column (M20). The position memory for the steering column and the outside rearview mirrors is located in the multi-function control module (N10).

The reference for the direction of rotation is provided by the multi-function control module (N10) with coding for left-hand drive/right-hand steering via the I-bus. Identification of the driver's/passenger seat is accomplished by installation of the switch group for the front power seat with memory (S91/S92) with or without switch for steering column adjustment (S91s11/S91s12 (LHS) or S92s11/S92s12 (RHS).

The motor group for seat forward/backward (M27m1/M28m1), seat height rear (M27m2/M28m2) and seat height front (M27m3/M28m3) are identical for the left and right seats, however, with locations reversed. This means that the control for the motors for the left and right seats is different.

Function prerequisites

The control module is operational only when the I-bus is active. Ignition on (terminal 15R or 15) or one of the front doors open.

Adjustment of the seat and storage of positions are possible only with:

Terminal 15R on or
Terminal 15 on or
one of bus doors open.

The corresponding information is read in via the I-bus.

Adjustment functions

One servo-motor is installed for each of the following functions:

Height adjustment at front
Forward/backward adjustment
Height adjustment at rear
Backrest adjustment
Head restraint adjustment

Group subdivision

The adjustment functions are subdivided into two groups. It is only possible to activate one motor per group simultaneously. The groups are subdivided as follows:

Group 1:

Forward/backward adjustment
Height adjustment at rear

Group 2:

Backrest adjustment
Height adjustment at front
Head restraint adjustment

Initial head restraint adjustment

The position of the head restraint is adjusted automatically corresponding to the forward/backward position of the seat.

The head restraint drive is activated only when the forward/backward position of the seat changes by more than 15 mm in order to allow slight correction of the forward/backward adjustment without changing the head restraint adjustment.

The following are prerequisites for proper function of the head restraint initial adjustment

Move seat forward to stop
Retract head restraint to stop
Then do not press control switch for approx. 4 s

Adjustment of the head restraint with the control switch (S91s4/S92s4) and adjustment of a stored position are independent of the head restraint initial adjustment function.

The position of the seat is sensed by one Hall sensor each in each of the motors for the adjustment functions.

Control buttons

Positions can be stored in two ways:

First hold the memory button (S91s9 or S92s9) depressed and simultaneously press the corresponding memory location button (S91s6/S91s7/S91s8 or S92s6/S92s7/S92s8).
First press the memory button (S91s9 or S92s9) and then release. Then press the corresponding memory location button (S91s6/S91s7/S91s8 or S92s6/S92s7/S92s8) (within ≤ 3 s).

Adjusting stored positions

Press the appropriate memory location button (S91s6/S91s7/S91s8 or S92s6/S92s7/S92s8) until the seat as well as exterior rearview mirrors and steering column have moved to the stored positions (via I-bus). During this operation one adjustment function per group is actuated for the power seat. If the position button is released while moving to a stored position, the adjustment operation stops immediately.

Protective features

A creep lock switch-off is stored to maintain the quality of the seat adjustment assembly and reduce hard mechanical stop.

For this purpose the "Positions" of the mechanical end stops are stored when the stops are reached for the first time (does not apply for rear stop for backrest adjustment).