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

MODEL 166 up to model year 2016 with CODE 275 (Memory package (driver seat, steering column, mirrors)) 

MODEL 166 up to model year 2016 with CODE P64 (Memory package) 

Function requirements, general 

• Circuit 30g On or run-on active
• No overvoltage or undervoltage

When circuit 30g is switched off, the power seats can still be adjusted for t = 180 s (run-on time). If, during the run-on time, the circuits status or the door status is changed, the run-on time starts again.

Electrical seat adjustment (ESA), general 

The ESE enables the electrical adjustment of the driver and front passenger seat (with CODE P64 (Memory package)). The driver and front passenger seats can be adjusted as follows:

• Seat fore/aft position
• Backrest inclination
• Seat height
• Seat inclination
• Head restraint height

The respective settings can also be saved and retrieved.

Priorities: The seat adjustment is divided up into two groups and two priorities. Each adjustment in a group is independent from an adjustment in another group. If several adjustment requests are received in a group by the driver seat control unit, then the adjustment request with the higher priority is executed.

The priorities are determined as follows:

Group 1:

• High priority: Fore/aft adjustment, steering column adjustment fore/aft, inclination adjustment

Group 2:

• High priority: Backrest inclination, steering column adjustment up/down, height adjustment
• Low priority: Head restraint adjustment

PRE-SAFE®: In certain danger situations, the front passenger seat is adjusted. Detailed information on this can be found in the separate "PRE-SAFE® function" function description.

The ESA includes the following subfunctions:

• Function sequence for position measurement 
• 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 position measurement 

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. When seat adjustments are being made, 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.

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.

In order to carry out the normalization procedure, the front mechanical end stop of the seat fore/aft position, the backrest inclination and the bottom mechanical end stop for the seat inclination, seat height and head restraint height must be moved to.

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. The status of the front seat adjustment switch group is read in via the front door LIN by the respective front door control unit. The respective front door control unit sends the requests from the front switch group, seat adjustment over the interior CAN to the driver seat control unit or the front passenger seat control unit. The driver seat or front passenger seat control unit actuates the relevant seat adjustment motors directly in accordance with the request. 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 for t < 2 s with active adjustment, this is considered blocking and the relevant adjustment function is deactivated by the driver seat or 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 setting is made with each front switch group, seat adjustment. The status of the front seat adjustment switch group is read in via the front door LIN by the respective front door control unit. The respective front door control unit sends the requests over the interior CAN to the driver seat control unit or to the front passenger control unit. To adjust, hold down the switches of the respective 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, height adjustment
• Seat adjustment motor, inclination adjustment
• Seat adjustment motor, head restraint adjustment'
• Seat adjustment motor, backrest inclination

Additional function requirements for saving and retrieving seat positions 

• ESA normalized

Function sequence for saving and retrieving seat positions 

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 for t < 100 ms, then press corresponding memory switch 1, 2 or 3 within t ≥ 0.2 s to 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 with an acknowledgment tone. The request for this is transmitted to the instrument cluster by the driver seat or front passenger seat control unit via the interior CAN.

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's seat control unit or the front passenger seat control unit actuates the seat adjustment motors accordingly.

Compensating movements: In order to avoid collisions when moving to seat positions, compensating movements are started. When adjusting the backrest to the rear, the fore/aft adjustment, height adjustment and the inclination adjustment are ended first and the backrest is then positioned. When adjusting the fore/aft adjustment to the rear, the seat backrest adjustment to the rear and the 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
• Height adjustment until memory position is reached, then inclination adjustment
• Fore/aft adjustment until memory position is reached, then inclination adjustment
• Seat backrest adjustment until memory position is reached, then inclination adjustment

Abort conditions:

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

As well as the seat position, the following settings are saved or retrieved:

• Pressure in the air cushions of the lumbar support
• Pressure in the air cushions of the multicontour seats (with CODE 399 (Front multicontour seats with massage function))
• Position of the steering column (when saving/retrieving position of driver seat)
• Adjustment of the outside mirror (when saving/calling up position of driver seat)

Detailed information about this can be found in the following separate function descriptions:

• "Lumbar support adjustment, function"
• "Multicontour seat (MKS), function"
• "Electrically adjustable steering column (ESC) function"
• "Electric mirror function"

	Electrical function schematic for seat adjustment (ESE) with memory		PE91.29-P-2054-97NAA
	Overview of system components, electric seats		GF91.29-P-9992GR