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Electrical Seat Adjustment (ESE) In Rear Passenger Compartment, Function - GF91.29-P-0013LF

Model 222 With Code 223 (Electric backrest adjustment and head restraints) 

G15400703Courtesy of MERCEDES-BENZ USA

Function requirements, general 

Electrical seat adjustment (ESA) in rear, general 

The ESA in the rear enables the electrical adjustment of the left and right rear seat. The left and the right rear seats can be adjusted as follows:

Moreover, it is possible to store and move to the particular seat position.

IMPORTANT Priorities:

The seat adjustment is divided up into 3 groups and 3 priorities. Each adjustment in a group is independent from an adjustment in another group. If adjustment requests for several adjustments are received in a group by the left rear seat control unit or the right rear seat control unit, the adjustment request with the highest priority is carried out.

The priorities are determined as follows:

Group 1:

Group 2:

Group 3:

The ESA includes the following subfunctions:

Function sequence for position measurement 

The seat adjustment motors are equipped with Hall sensors. The signals from the Hall sensors are directly read in and evaluated by the right rear seat control unit or the left rear seat control unit.

Normalization resets a location counter in the right rear seat control unit or the left rear seat control unit. When adjusting seats, the right rear seat control unit or the left rear seat control unit defines the adjustment range of the seats by counting the Hall sensor signals.

Additional function requirements for normalization 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 via interior CAN to the right rear seat control unit and to the left rear seat control unit.

Function sequence for normalization 

Normalization is the basis for assigning the current position to the seat position that is recorded by the left rear seat control unit or the right rear seat control unit. Normalization must be performed during initial startup or in a denormalized condition.

The following mechanical stops have to be moved to for the normalization procedure:

To this end, the corresponding switch in the switch group, seat adjustment must remain actuated for t = 250 ms after the mechanical end stop has been reached. Upon successful normalization, the left rear seat control unit or the right rear seat control unit switches off the corresponding seat adjustment motor. During the initial startup, the normalization is performed with the diagnostic tester.

IMPORTANT An adjustment is denormalized if the signal of the corresponding Hall sensor is not received. The denormalization procedure can also be performed via diagnosis.

Function sequence for antilock device 

If the Hall sensor signals are not received for an active adjustment for t > 2 s, this is recognized as blocking and the corresponding adjustment function is deactivated after t = 2 s by the left rear seat control unit or the right rear seat control unit. Reactivation in the same adjusting direction is not possible until the corresponding switch has been released for approx. t ≥ 2 s. Re-enabling in the opposite adjustment direction is immediately possible.

Function sequence for manual adjustment 

The manual adjustment function comprises the following subfunctions:

Function sequence for manual adjustment of rear seat 

Manual adjustment is done using the rear seat adjustment switch group. Operation of the rear seat adjustment switch group is read in rear door LIN by the respective rear door control unit. The respective rear door control unit transmits the requests from the corresponding rear seat adjustment switch group via interior CAN to the left rear seat control unit or to the right rear seat control unit. To adjust, hold down the switches in the rear seat adjustment switch group until the desired position is reached.

The left rear seat control unit or the right rear seat control unit actuates the following motors directly depending on the request:

IMPORTANT Model 222 with code 223 (Electric backrest adjustment and head restraints) with code P07 (Chauffeur package)

By actuating the right rear seat fully reclined position switch in the right rear seat switch group, seat adjustment, the front passenger seat is moved to chauffeur mode and the right rear seat is moved to a fully reclined position.

Function sequence for manual adjustment of front passenger seat via the rear switch group 

You can switch between front passenger and right rear seat adjustment by operating the front passenger seat adjustment switch or right rear seat adjustment switch in the right rear seat switch group, seat adjustment. When switching over to front passenger seat adjustment, the front passenger seat can be manually adjusted for t = 10 s. The active front passenger seat adjustment is shown by the light-emitting diode in the front passenger seat adjustment switch or right rear seat adjustment switch. After expiration of t = 10 s or if the front passenger seat adjustment switch or right rear seat adjustment switch is operated again, the right rear seat can be adjusted again.

The status of the right rear seat switch group, seat adjustment is read in via the right rear door LIN by the right rear door control unit. The right rear door control unit sends the "Right rear front passenger seat adjustment active" signal via interior CAN to the right rear seat control unit and to the front passenger seat control unit.

To adjust, hold down the switches in the right rear seat switch group, seat adjustment until the desired position is reached. The adjustment requests are sent by the right rear door control unit via interior CAN to the front passenger seat control unit.

The following settings are possible:

IMPORTANT The seat heater and the seat ventilation on the passenger-side cannot be operated from the rear.

IMPORTANT Additionally, the seat positions of the front passenger seat can be stored or retrieved via the memory function in the rear. The memory positions stored on the passenger side remain unchanged.

Additional function requirements for saving and retrieving seat positions 

Function sequence for saving and retrieving seat positions 

There are two button operation options for storing the seat position:

The respective rear door control unit reads in the status of the switches in the rear seat adjustment switch group via the rear door LIN and sends the request "Store memory position" via interior CAN to the left rear seat control unit or to the right rear seat control unit. The left rear seat control unit or the right rear seat control unit uses the signals of the Hall sensors to store the current seat position.

IMPORTANT Successful storage of the seat position is confirmed by the instrument cluster speaker with an acknowledgment tone. The request for this is sent by the left rear seat control unit or the right seat control unit via interior CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster, which actuates the instrument cluster speaker directly.

To retrieve saved seat positions, press and hold corresponding memory switch 1, 2 or 3 until the stored end position is reached. Releasing leads to immediate termination of the adjustment procedure. The respective rear door control unit reads in the status of the switches in the rear seat adjustment switch group via the rear door LIN and sends the request "Adopt memory position" via interior CAN to the left rear seat control unit or to the right rear seat control unit. The left rear seat control unit or the right rear seat control unit actuates the corresponding seat adjustment motors directly.

Abort conditions:

Additional function requirements for seat belt comfort-fit function 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 via interior CAN to the right rear seat control unit and to the left rear seat control unit.

The supplemental restraint system control unit sends the respective seat belt buckle status over the user interface CAN, electronic ignition lock control unit and interior CAN to the right rear seat control unit or to the left rear seat control unit.

The active belt buckle control unit (with code 305 (Rear PRE-SAFE)) sends the status of the respective active belt buckle via interior CAN to the right rear seat control unit or to the left rear seat control unit.

Function sequence for seat belt comfort-fit function 

The seat belt comfort-fit function reduces the extension and retraction forces of the seat belt inertia reel when the seat belt is being worn, thus making it more pleasant for the occupants to wear the belt. To do this, the right rear seat control unit or the left rear seat control unit actuates the seat belt comfort-fit function, left rear seat solenoid or the seat belt comfort-fit function, right rear seat solenoid directly.

After changing from circuit 15R to circuit 15C, the function is stopped after t = 5 min. After changing from circuit 15C On to circuit 15C Off, the function is stopped immediately.

Additional function requirements for head restraint presetting 

Function sequence for head restraint presetting 

The head restraint inclination is automatically preset by the left rear seat control unit or by the right rear seat control unit depending on the backrest inclination. Depending on the current position of the head restraint inclination, it is also adjusted in stages when adjusting the backrest inclination forward or back.

IMPORTANT The head restraint presetting function can be switched on and off using a diagnostic tester and is coded after installation according to the country.

Additional function requirements for head restraint compensation during head restraint inclination adjustment 

Function sequence for head restraint compensation during head restraint inclination adjustment 

The head restraint height is automatically adjusted by the left rear seat control unit or by the right rear seat control unit depending on the head restraint inclination.

If the head restraint is inclined forward, the head restraint moves up at the same time. If the head restraint is inclined backward, the head restraint moves down at the same time. The head restraint is adjusted based on a target curve with parameters that can be adjusted via diagnosis.

IMPORTANT The head restraint compensation function during head restraint inclination adjustment can be switched on and off using a diagnostic tester and is coded after installation according to the country.

Additional function requirements for collision avoidance of rear reclining seat with front seat (With Code 453 (Rear reclining seats)) 

Function sequence for collision avoidance of rear reclining seat with front seat (With Code 453 (Rear reclining seats)) 

Moving the fore/aft adjustment of the driver or front passenger seat to the rear or adjusting the leg rest on the respective rear seat can lead to collisions.

If the driver or front passenger seat is located within the collision area, one of the following actions can be performed:

A new seat adjustment is only possible once the rest position of the respective switch has been recognized.

IMPORTANT The behavior of the fore/aft adjustment to the rear in the collision area can be adjusted using the diagnosis.

Function sequence for rear PRE-SAFE® positioning function (With Code 305 (Rear PRE-SAFE)) 

The rear seats PRE-SAFE® positioning function is activated in case of a critical driving situation, i.e. in a potential accident situation. This seat adjustment that takes place prior to the potential impact is supposed to achieve better occupant positioning for the subsequent accident.

The Electronic Stability Program control unit sends information on the PRE-SAFE® status and the request for a PRE-SAFE® adjustment via chassis FlexRay, electronic ignition lock control unit and interior CAN to the left rear seat control unit and to the right rear seat control unit.

Fault handling function sequence 

The left rear seat control unit or the right rear seat control unit checks the requests for seat settings it has received for plausibility. Adjustment requests for the same adjustment function in opposing directions (e.g. backrest inclination forwards//back simultaneously) are rejected. Correct requests for other adjustment functions remain unaffected. The plausibility of a manual adjustment request for a memory adjustment is checked by the left rear seat control unit or the right rear seat control unit.

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