Electrical Seat Adjustment (ESA) - GF91.29-P-0009LF

Model 217, 222

Courtesy of MERCEDES-BENZ USA

Function requirements, general

No overvoltage or undervoltage

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 fore/aft position
Backrest inclination
Seat height
Seat inclination
Seat cushion length (model 222 with code P64 (Memory package) or model 217)
Head restraint height
Head restraint angle (model 222 with code 439 (EASY ADJUST luxury head restraint))

Furthermore, on model 222 with code 275 (Memory package) or model 217, the respective seat position can be stored and retrieved together with other settings.

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 driver's seat control unit or the front passenger seat control unit, the adjustment request with the highest priority is carried out.

The priorities are determined as follows:

Group 1:

High priority: fore/aft adjustment, steering column fore/aft adjustment (driver's seat only)
Low priority: inclination adjustment

Group 2:

High priority: backrest inclination, steering column adjustment up/down (driver's seat only)
Low priority: seat height adjustment

Group 3:

High priority: head restraint adjustment, seat cushion length

The ESA includes the following subfunctions:

Function sequence for position detection
Function sequence for normalization
Function sequence for antilock device
Function sequence for manual adjustment
Function sequence for storing and retrieving seat positions (model 222 With Code 275 (Memory package) or model 217)
Function sequence for rear compartment access (model 217)
Function sequence for seat belt comfort-fit function
Function sequence for head restraint presetting
Function sequence for head restraint compensation during head restraint inclination adjustment
Function sequence for front passenger head restraint lowering mechanism
Function sequence for PRE-SAFE® front passenger seat positioning function
Function sequence for folding down front passenger head restraint (model 222 With Code 439 (EASY ADJUST luxury head restraint), Except Code 494 (USA version) and Except Code 460 (Canada version))
Function sequence for front passenger seat chauffeur mode (model 222 With Code P07 (Chauffeur package))
Fault handling function sequence

Function sequence for position detection

The seat adjustment motors are equipped with Hall sensors. The signals from the Hall sensors are read in and evaluated by the driver's seat control unit or the front passenger seat control unit directly.

Normalization resets a location counter in the driver's seat control unit or the front passenger seat control unit. During seat adjustments, the driver seat control unit or the front passenger seat control unit defines the adjustment range of the seats by counting the Hall sensor signals.

Additional function requirements for normalization

Circuit 15R ON

The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN to the driver seat control unit and to the front passenger seat control unit.

Function sequence for normalization

Normalization is the basis for assigning the instantaneous position to the seat position that is recorded by the driver seat control unit or the front passenger 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:

Front end stop for seat fore/aft position and backrest inclination
Downstop of seat height and head restraint height
Upper stop for seat inclination
Rear end stop for seat cushion length

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

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 during active adjustment for t > 2 s, this is recognized as blocking and the corresponding adjustment function is deactivated after t = 2 s by the driver seat control unit or the front passenger 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 front seats
Function sequence for manual adjustment of front passenger seat via the left switch group, seat adjustment (driver side) (model 222 With Code P64 (Memory package) or model 217)
Function sequence for manual adjustment of front passenger seat via the switch group in rear (model 222 With Code 223 (Electrically adjustable rear bench seat))

Function sequence for manual adjustment of front seats

Manual adjustment is conducted using the seat adjustment switch group. Operation of the front switch group, seat adjustment is read in over each front door LIN by the respective front door control unit. The respective front door control unit sends the requests from the corresponding front seat adjustment switch group via interior CAN to the driver seat control unit or to the front passenger seat control unit.

To adjust, hold down the switches in the front switch group, seat adjustment until the desired position is reached.

The driver seat control unit or the front passenger seat control unit actuates the following motors directly depending on the request:

Seat adjustment motor, seat fore/aft adjustment
Seat adjustment motor, head restraint adjustment'
Seat adjustment motor, backrest inclination
Seat cushion length adjustment seat adjustment motor (model 222 with code P64 (Memory package) or model 217)
Seat adjustment motor for seat inclination adjustment
Seat adjustment motor for seat height adjustment
Head restraint angle motor (model 222 with code 439 (EASY ADJUST luxury head restraint))

Function sequence for manual adjustment of front passenger seat via the left switch group, seat adjustment (driver side) (model 222 With Code P64 (Memory package) or model 217)

You can switch between driver and front passenger seat adjustment by operating the left or right seat adjustment switch in the left front 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 left or right seat adjustment switch. After expiration of t = 10 s or if the left or right seat adjustment switch is operated again, the driver seat can be adjusted again.

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

To adjust, hold down the switches in the left front switch group, seat adjustment until the desired position is reached. The adjustment requests are sent by the left front door control unit via interior CAN to the front passenger seat control unit. The front passenger seat control unit directly actuates the corresponding seat adjustment motors to match the request.

Model 217, 222

with code 401 (Climatised front seats)

Model 217, 222

with code 432 (Left and right dynamic multicontour seat)

Model 217, 222

with code 873 (Seat heating for driver and front passenger)

The seat heater and the seat ventilation on the passenger side can also be operated from the driver side.

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

Function sequence for manual adjustment of front passenger seat via the switch group in rear (model 222 With Code 223 (Electrically adjustable rear bench seat))

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 front passenger seat control unit directly actuates the corresponding seat adjustment motors to match the request.

The following settings are possible:

Seat fore/aft position
Backrest inclination
Seat height
Head restraint height
Head restraint angle (model 222 with code 439 (EASY ADJUST luxury head restraint))
Footrest forward/back (model 222 with code P07 (Chauffeur package))

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

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 storing and retrieving seat positions (model 222 With Code 275 (Memory package) or model 217)

ESA normalized

Function sequence for storing and retrieving seat positions (model 222 With Code 275 (Memory package) or model 217)

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

Press and hold left front or right front memory function switch, then press corresponding memory switch 1, 2 or 3 for relevant memory.
Press and release left front or right front memory function switch, then press corresponding memory switch 1, 2 or 3 within t 3 s for the relevant memory.

The respective front door control unit reads in the status of the switches in the front switch group, seat adjustment via front door LIN and sends the request "Store memory position" via interior CAN to the driver seat control unit or the front passenger seat control unit. The driver's seat control unit or front passenger seat control unit uses the signals of the Hall sensors to store the current seat position.

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 driver seat control unit or the front passenger seat control unit over the 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 front door control unit reads in the status of the switches in the front switch group, seat adjustment via front door LIN and sends the request "Adopt memory position" via interior CAN to the driver seat control unit or the front passenger seat control unit. The driver seat control unit or the front passenger seat control unit actuates the corresponding seat adjustment motors directly.

Abort conditions:

Manual seat adjustment
Manual mirror adjustment (driver only)
Manual steering column adjustment (driver only)
Pressing other memory switches

Compensating movements:

If collisions occur despite the defined priorities, compensating movements are started. When adjusting the backrest to the rear, the fore/aft adjustment, seat height adjustment and inclination adjustment are ended first and the backrest is then positioned.

When adjusting the fore/aft adjustment to the rear, the backrest adjustment to the rear and the seat height adjustment upwards, the memory setting is implemented according to the following procedure:

Fore/aft adjustment to the rear up to the characteristic map limit, then inclination adjustment
Stop fore/aft adjustment at characteristic map limit
Seat height adjustment up to memory position reached, then inclination adjustment
Fore/aft adjustment up to memory position reached, then inclination adjustment
Seat backrest adjustment up to memory position reached, then inclination adjustment

Additional function requirements for rear compartment access (model 217)

ESA normalized
Respective vehicle door opened

The status of the corresponding door (open/closed) is sent by the respective front door control unit via interior CAN to the driver seat control unit or to the front passenger seat control unit.

Function sequence for rear compartment access (model 217)

In order to ease access to the rear compartment and to avoid collisions with the headliner or the soft top when folding the seats forward, the seats are moved to rear compartment access position when folded forward.

The current position (initial position) of the seat is stored via the position detection.

The backrest release/backrest inclination microswitches each consist of two microswitches, the backrest release microswitch and the backrest inclination microswitch.

Pulling the backrest release handle releases the backrest and it can then be folded forward. The backrest release microswitch is closed during release. The following adjustments are then started simultaneously in the rear compartment access position:

Head restraint height adjustment
Seat height adjustment

The driver seat control unit or front passenger seat control unit reads in the status of the respective backrest release microswitch directly and then actuates the corresponding seat adjustment motors.

The backrest inclination microswitch is closed when the backrest is folded forward. The following adjustments are then started simultaneously in the rear compartment access position:

Seat fore/aft adjustment
Seat height adjustment
Seat cushion length adjustment (not until head restraint height adjustment is completed)
Seat backrest adjustment (not until seat height adjustment is completed)

The driver seat control unit or front passenger seat control unit reads in the status of the respective backrest inclination microswitch directly and then actuates the corresponding seat adjustment motors.

The backrest inclination microswitch is opened when the backrest is folded back. Then, the following adjustments are started simultaneously in the default position:

Seat fore/aft adjustment
Seat height adjustment
Seat cushion length adjustment

The backrest release microswitch is opened when the backrest is locked. Then, the following adjustments are started simultaneously in the default position:

Head restraint height adjustment
Backrest adjustment

Moving to the rear compartment access position or default position without reaching the respective end position by folding the backrest forward/back in turns is limited to three times. If the backrest is folded forward/back for the fourth time without having been locked and released in the meantime, no more adjustment is triggered.

Abort conditions:

Undervoltage or overvoltage
Vehicle speed v > 12 km/h
Fault detected in the backrest release/backrest inclination microswitch
Actuating a switch in the front switch group, seat adjustment
PRE-SAFE® triggering

Additional function requirements for seat belt comfort-fit function

Circuit 15R or circuit 15 ON
Respective belt tab inserted

The electronic ignition lock control unit sends the status of circuit 15 over the interior CAN to the driver seat control unit and to the front passenger seat control unit.

The supplemental restraint system control unit sends the respective seat buckle status over the user interface CAN, electronic ignition lock control unit and interior CAN to the driver seat control unit or to the front passenger 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 driver seat control unit or the front passenger seat control unit actuates the seat belt comfort-fit function, driver seat solenoid or the seat belt comfort-fit function, front passenger 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

ESA normalized

Function sequence for head restraint presetting

The height of the head restraint is automatically preset by the driver seat control unit or by the front passenger seat control unit depending on the seat fore/aft position. If the seat is moved forward, the head restraint moves down. If the seat is moved back, the head restraint moves up. The head restraint is adjusted in stages.

The head restraint inclination is automatically preset by the driver seat control unit or by the front passenger 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.

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

ESA normalized

Function sequence for head restraint compensation during head restraint inclination adjustment

The head restraint height is automatically adapted by the driver seat control unit or by the front passenger 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.

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 front passenger head restraint lowering mechanism

Circuit 15R ON
ESA normalized

The electronic ignition lock control unit sends the status of circuit 15 to the front passenger seat control unit via interior CAN.

Function sequence for front passenger head restraint lowering mechanism

If the front passenger seat is not occupied, the head restraint moves to the lower stop in order to improve the rear occupant's view to the front. When the passenger side seat is occupied, the head restraint moves back to its original position. This function is executed by the front passenger seat control unit only.

The function is activated depending on the seat belt buckle status and the seat occupancy recognition on the front passenger seat. The supplemental restraint system control unit sends the status of the seat occupied recognition and the status of the belt buckle over the user interface CAN, electronic ignition lock control unit and interior CAN to the front passenger seat control unit. The front passenger seat control unit actuates the front passenger seat head restraint adjustment motor correspondingly.

Additional function requirements for PRE-SAFE® front passenger seat positioning function

ESA normalized
Front passenger seat occupied

The supplemental restraint system control unit sends the status of the front passenger seat occupied recognition over the user interface CAN, electronic ignition lock control unit and interior CAN to the front passenger seat control unit.

Function sequence for PRE-SAFE® front passenger seat positioning function

In order to optimize the protective effect of the conventional restraint equipment, the front passenger seat is moved into a position that is favorable from a safety point of view before a potential accident. The Electronic Stability Program control unit sends information about the PRE-SAFE® status and the request for PRE-SAFE® adjustment via the chassis FlexRay, electronic ignition lock control unit and interior CAN to the front passenger seat control unit. Any memory or manual setting that may be active is aborted.

Additional function requirements for folding down front passenger head restraint (model 222 With Code 439 (EASY ADJUST luxury head restraint), Except Code 494 (USA version) and Except Code 460 (Canada version))

ESA normalized
Circuit 15R or circuit 15 ON
Passenger door CLOSED
Front passenger head restraint inserted
Passenger seat unoccupied
Front passenger seat belt not inserted

The electronic ignition lock control unit sends the status of circuit 15 to the front passenger seat control unit via interior CAN.

The right front door control unit transmits the status of the front passenger door (open/closed) via interior CAN to the front passenger seat control unit.

The status of the front passenger head restraint (inserted/not inserted) is recorded by the front passenger seat head restraint (inserted) microswitch and read in directly by the front passenger seat control unit.

The supplemental restraint system control unit sends the status of the seat occupied recognition and the status of the belt buckle over the user interface CAN, electronic ignition lock control unit and interior CAN to the front passenger seat control unit.

Function sequence for folding down front passenger head restraint (model 222 With Code 439 (EASY ADJUST luxury head restraint), Except Code 494 (USA version) and Except Code 460 (Canada version))

The front passenger head restraint can be folded down towards the front using the following controls:

Right rear seat adjustment switch group
Left front seat adjustment switch group

When the front passenger seat adjustment switch or right rear seat adjustment switch in the right rear seat switch group, seat adjustment or the left or right seat adjustment switch in the left front switch group, seat adjustment is pressed, the system switches to front passenger seat adjustment.

Afterwards, the head restraint inclination must be adjusted towards the front using the right rear seat head restraint adjustment switch or the left front head restraint adjustment switch until it reaches the limit stop. If the function head restraint inclination towards the front is triggered again, the head restraint is completely folded down. If the head restraint is folded down, the front passenger head restraint inclination microswitch is actuated. The front passenger seat control unit reads in the status of the front passenger head restraint inclination microswitch directly.

The front passenger seat control unit then actuates the front passenger seat head restraint inclination motor directly.

When folded down, the head restraint can be mechanically unlocked and removed.

The front passenger head restraint is raised automatically if one of the following events occurs:

Actuation of a switch in the right front switch group, seat adjustment
Brief actuation of the right rear seat head restraint adjustment switch or the left front head restraint adjustment switch towards the rear
Front passenger belt buckle is recognized as inserted
Front passenger seat is recognized as occupied

Additional function requirements for front passenger seat chauffeur mode (model 222 With Code P07 (Chauffeur package))

ESA normalized
Circuit 15R or circuit 15 ON
Passenger door CLOSED
Front passenger head restraint inserted
Passenger seat unoccupied
Front passenger seat belt not inserted

The electronic ignition lock control unit sends the status of circuit 15 to the front passenger seat control unit via interior CAN.

The right front door control unit transmits the status of the front passenger door (open/closed) via interior CAN to the front passenger seat control unit.

Function sequence for front passenger seat chauffeur mode (model 222 With Code P07 (Chauffeur package))

The chauffeur mode of the front passenger seat provides more space for the occupants in the right rear and a more comfortable seat position.

The front passenger seat can be moved to the chauffeur mode via the following controls:

Right rear seat adjustment switch group
Left front seat adjustment switch group

Afterwards, the fore/aft adjustment of the front passenger seat must be moved towards the front using the right rear seat inclination adjustment switch or the left front seat fore/aft adjustment switch until it reaches the limit stop. When the fore/aft adjustment function is activated again towards the front, the front passenger seat is adjusted as per the following function sequence:

The seat height adjustment moves upwards or downwards to a defined intermediate position and the inclination adjustment simultaneously moves upwards until it reaches its end position
The seat backrest adjustment moves forward to a defined position
The head restraint is moved to the lowermost position, inclined forward and then folded down

In chauffeur mode, the driver's view of the right outside mirror may be impaired by the front passenger head restraint that was folded down. Therefore, the front passenger head restraint can be mechanically unlocked and removed.

The fore/aft adjustment moves to the front end stop and the seat height adjustment moves to the upper stop

The front passenger seat control unit then actuates the corresponding motors directly.

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.

Additionally, the footrest under the front passenger seat can be extended and retracted using the right rear seat switch group, seat adjustment. To do this, the front passenger seat control unit actuates the footrest adjustment actuator motor directly.

If the head restraint is folded down, the driver head restraint inclination microswitch or front passenger head restraint inclination microswitch is actuated. The driver seat control unit or the front passenger seat control unit reads in the status of the corresponding head restraint inclination microswitch directly.

Model 222

with code 864 (Rear compartment entertainment package)

Depending on the backrest inclination of the front passenger seat, the inclination of the right rear display (A40/6) is also adapted to allow the best possible view for the rear passengers. To do this, the front passenger seat control unit actuates the screen adjustment actuator motor directly.

The front passenger seat moves back to its normal position automatically if one of the following events occurs:

Actuation of a switch in the right front switch group, seat adjustment
Front passenger belt buckle is recognized as inserted
Front passenger seat is recognized as occupied
Front passenger head restraint is raised using right rear seat switch group, seat adjustment or left front switch group, seat adjustment

To manually exit the front passenger seat chauffeur mode, the right rear seat inclination adjustment switch or the left front seat fore/aft adjustment switch must be pressed backward and held until the front passenger seat has reached the normal position.

The chauffeur mode of the front passenger seat can not be stored with the driver seat or front passengers seat memory function. It can be stored using the right rear seat adjustment switch group.

Fault handling function sequence

The driver seat control unit or the front passenger seat control unit checks the requests for seat settings it has received for plausibility. Adjustment requests for the same adjustment function in an opposite direction (e.g. backrest inclination forward//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 front door control unit or the right front door control unit.

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