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

Model 463 (except 463.342) 

as of model year 2013 

Courtesy of MERCEDES-BENZ USA

Model 463 as of 03.04.2018 

Courtesy of MERCEDES-BENZ USA

Model 463 up to 02.04.2018 

Function requirements, general 

• Circuit 30g or 30t ON
• 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 longitudinal direction
• Backrest inclination
• Seat height
• Seat inclination
• Seat cushion length (as of 03.04.2018)
• Head restraint height

Furthermore, the respective seat position can be stored and called up together with other settings.

Priorities:

The seat adjustment is divided up into three groups and three 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 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:

• Priority high: Head restraint adjustment, seat cushion length (as of 03.04.2018)

Model 463 (except 463.342)

as of model year 2019

PRE-SAFE®:

To enable a favorable seat position to be adopted by the vehicle occupants in critical situations, the front passenger seat is automatically adjusted.

The ESA function comprises the following subfunctions:

• Function sequence for position recognition 
• Function sequence for normalization 
• Function sequence for antilock device 
• Function sequence for manual adjustment 
• Function sequence for saving and retrieving seat positions 
• Function sequence for EASY-ENTRY (on model 463.20) 
• Function sequence for head restraint presetting (as of 03.04.2018) 
• Error handling 

Function sequence for position recognition 

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. For seat adjustment units, the driver or 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.

On model 463 as of 03.04.2018 the following mechanical stops have t be moved to for the normalization procedure:

• Front end stop with seat fore-and-aft position and seat backrest inclination
• Downstop for seat height and head restraint height
• Upper stop with seat inclination
• Rear end stop with seat cushion length

On model 463 up to 02.04.2018 the following mechanical stops have to be moved to for the normalization procedure:

• Front end stop with seat fore-and-aft position and seat backrest inclination
• Downstop for seat inclination, seat height and head restraint height

Here, the corresponding switch in the front switch group, seat adjustment must remain activated for 250 ms after reaching the mechanical end stop. 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 

The driver seat control unit or the front passenger seat control unit continuously monitors the power consumption of the seat adjustment motors. If the power consumption is too high (e.g. due to blocked seat adjustment), the driver seat control unit or the front passenger seat control unit switches the corresponding seat adjustment motor off.

Function sequence for manual adjustment 

The manual setting is made with each front switch group, seat adjustment. The respective front door control unit reads in the status of the front switch group, seat adjustment via front door LIN and sends the adjustment requests via interior CAN to the driver seat control unit or 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, backrest inclination
• Seat adjustment motor for seat height adjustment
• Seat inclination adjustment seat adjustment motor (as of 03.04.2018) or inclination adjustment seat adjustment motor (up to 02.04.2018)
• Seat cushion length adjustment seat adjustment motor (as of 03.04.2018)
• Seat adjustment motor, head restraint adjustment'

Additional function requirements for saving and retrieving seat positions 

• ESA normalized

Function sequence for saving and retrieving seat positions 

The seat position can be stored and called up again together with other settings.

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

• Press and hold down the front memory function switch and then press memory switch 1, 2 or 3 for the respective memory.
• Press front left or front right memory function switch for 100 ms and release. Then press the corresponding memory switch 1, 2 or 3 within 0.2 to 3 s for each memory preset.

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.

Storage of the seat position is confirmed by the instrument cluster with an acknowledgment tone. On vehicles as of 03.04.2018 front passenger seat control unit sends the request over the interior CAN, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. On vehicles up to 02.04.2018 the front passenger seat control unit sends the request over the interior CAN to the instrument cluster. The instrument cluster actuates the instrument cluster speaker (as of 03.04.2018) or the integrated warning buzzer (up to 02.04.2018) to emit the acknowledgement tone directly. As well as the seat position, the following settings are saved or retrieved:

• Steering column position (when saving/calling up the driver seat position): The current position is recorded and saved by the driver seat control unit.
• Outside mirror position (when saving/calling up the driver seat position): The current position is recorded and saved by the left front door control unit and the right front door control unit. The driver seat control unit transmits the request to save/call up the outside mirror position via interior CAN to the left front door control unit and to the right front door control unit.

To retrieve saved 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. The adjustment of the memory position is interrupted under the following conditions:

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

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 moving the fore/aft adjustment to the rear, the seat backrest adjustment to the rear and the seat height adjustment upwards, the memory is set according to the following sequence:

• 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, until the memory position is reached then the inclination adjustment
• Fore/aft adjustment until memory position is reached, then inclination adjustment
• Seat backrest adjustment, until memory position is reached, then inclination adjustment

Additional function requirements for EASY-ENTRY (on model 463.20) 

• ESA normalized
• Corresponding door opens or circuit 15 ON (irrespective of whether the corresponding door is opened or closed)

The respective front door control unit transmits the corresponding door status via interior CAN to the driver seat control unit or to the front passenger seat control unit.

The status of circuit 15 is transmitted by the electronic ignition lock control unit via the interior CAN to the driver seat control unit and the front passenger seat control unit.

Function sequence for EASY-ENTRY (on model 463.20) 

In order to facilitate access to the rear passenger compartment, the following settings are made when folding the corresponding backrest forward:

• Seat cushion and head restraint move downwards.
• Front seat moves forward, the seat cushion inclination is adjusted.
• Seat backrest is moved forward.

Additionally, the steering wheel on the driver side is moved forwards and then upwards.

By pulling the backrest release handle, the seat is released manually and can be folded forward. The front seat backrest release microswitch is thereby actuated (electrically closed). The current position of the seat is stored via the position detection.

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

The EASY-ENTRY position of the respective front seat is adjustable via diagnosis.

When folding back the front seat, the front seat backrest release microswitch is released (electrically opened). The front seat assumes the previously stored default position again.

If the position of the fore/aft adjustment is located behind the EASY-ENTRY position, the front seat is no longer moved for safety reasons. The backrest inclination may also not exceed a certain position toward the rear.

The EASY-ENTRY adjustment is aborted under the following conditions:

• Request for seat adjustment pending.
• Request for steering column adjustment pending.
• Vehicle speed is higher than 12 km/h.

The instrument cluster sends the vehicle speed via interior CAN to the driver seat control unit and the front passenger seat control unit.

Warning message: 

If the respective front seat is not locked when the engine is running, the driver or front passenger seat control unit sends a request to output a warning message via the interior CAN to the instrument cluster. The warning message is shown in the multifunction display.

Additional function requirements for head restraint presetting (as of 03.04.2018) 

• ESA normalized

Function sequence for head restraint presetting (as of 03.04.2018) 

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 setting for 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 presetting function can be switched on and off using a diagnostic tester and is coded after installation according to the country.

Error handling 

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.

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