Rear passenger compartment electrical seat adjustment, basic function

Overview:

This document contains information on:

 General

 Function requirements

 Seat heater and head restraint adjustment

 Folding seat backrest forward and back electrically.

 EASY-ENTRY function

 Plausibility check

 Antilock device

General

The electrical seat adjustment in the rear passenger compartment allows the rear seats to be adjusted by actuating motors that bring the individual parts of the rear seats into the desired position. In order to achieve the best possible leg clearance and forward visibility, the front passenger seat can also be adjusted from the rear passenger compartment if certain comfort equipment is installed (e.g. reclining rear seat). Depending on the model and equipment involved, the following settings are possible:

 Backrest inclination

 Head restraint height

 Seat fore/aft position

 Seat height

 Leg rest inclination (with reclining rear seat)

 Leg rest fore/aft adjustment (with reclining rear seat)

 Predefined seat positions (with reclining rear seat):

 UPRIGHT

 Reclined position

 Front passenger seat (with reclining rear seat): Seat fore/aft position and seat backrest inclination forward to maximum permissible value (chauffeur mode)

 Depending on the model and model designation concerned, the reclining rear seat is available either only on the front passenger side or simultaneously on the left and right.

In the third seat row, it is only possible to adjust the seat backrest inclination.

Electrical seat adjustment in the rear passenger compartment is controlled by the respective seat control unit or by the rear signal acquisition and actuation module. In the third seat row, the respective seat control unit in the second seat row controls the seat backrest inclination.

Function requirements

 Circuit 30t

 No overvoltage or undervoltage

Seat heater and head restraint adjustment

The rear seats are adjusted using the respective seat adjustment switch group in the rear doors. The seat control unit for each seat directly actuates the corresponding adjustment motors as requested.

Depending on the model and equipment, it is also possible to adjust the rear seats via an onboard tablet PC. The removable tablet PC is mounted at one of the following positions:

 Rear armrest

 Rear passenger compartment center console

Folding seat backrest forward and back electrically.

The seat backrests of the rear seats can be folded forward and back using the buttons in the load compartment. On many vehicle models, the center seat backrest folds forward together with the left seat backrest. In addition, the head restraints move into a suitable position.

The seat control unit of the respective seat or of the second seat row or the rear signal acquisition and actuation module actuates the corresponding adjustment motors.

 If a seat backrest in the second or third seat row is not engaged and locked, this is displayed on the instrument cluster display.

EASY-ENTRY function

Additional function requirements (depending on the equipment):

 The stowage compartment in the center console is closed.

 The armrest is folded up.

The rear seats can be folded forward to make it easier to access the load compartment or to enter or exit vehicles with a third seat row. In addition, the head restraints move into a suitable position.

It is operated via the respective easy entry and exit feature switch in the upper area of the sear backrests. The seat control unit for each seat directly actuates the corresponding adjustment motors.

Plausibility check

The seat control unit checks the received requests for seat adjustments in terms of plausibility. Adjustment requests for the same adjustment function in an opposite direction (e.g. simultaneous seat backrest inclination forward//back) are canceled by the seat control unit. Correct requests for other adjustment functions remain unaffected.

Antilock device

The corresponding seat control unit monitors the position change of the seat during the adjustment with the help of the Hall sensors. If blocking is detected, the seat control unit switches off the corresponding seat adjustment motor.

The seat control unit also monitors the power consumption of the seat adjustment motors. When the power consumption is too high (e. g. through seat adjustment blocking) the seat control unit switches off the corresponding seat adjustment motor.