Electric seat adjustment (ESA) function - GF91.29-P-0004G

MODEL 463.306 /336 /346 up to 31.5.12 as of model year 2011/YoM 10 

MODEL 463.202 /222 /236 /237 /270 /271 /303 /340 /341 up to 31.5.12 as of model year 2009/YoM 08 

Front seats 

Rear seats (with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7 with individual rear seats) 

Function requirements, general 

• Circuit 15R ON or
• Respective door open

The circuit status of circuit 15 is provided by the EZS control unit via interior CAN.

Electric seat adjustment (ESA [ESV]), general 

The driver seat and front passenger seat are electrically adjustable.

With code (ZS6) Special protection version FB6 or code (ZS7) Special protection version FB7 with individual rear seats, the left rear seat and the right rear seat are also electrically adjustable.

The front seat adjustment is operated via the front seat adjustment switch groups in the respective door trims.

The rear seat adjustment is operated via the rear individual seat adjustment switch groups in the center console.

The following adjustment options can be operated:

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

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

On the driver-side, the positions of the outside mirrors and the steering column are also stored and retrieved via the memory function.

Components of the rear seat ESA [ESV] cannot be diagnosed.

The ESA [ESV] consists of the following subfunctions:

• Function sequence for manual adjustment 
• Function sequence for memory 
• Normalization function sequence 
• Function sequence for position measurement 
• Function sequence for antilock device 
• Fault handling function sequence 

Function sequence for manual adjustment 

The function sequence for manual adjustment consists of the following subfunctions:

• Function sequence for manual adjustment of driver seat 
• Function sequence for manual adjustment of front passenger seat 
• Function sequence for manual adjustment of left rear seat (with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7 with individual rear seats) 
• Function sequence for manual adjustment of right rear seat (with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7 with individual rear seats) 

Function sequence for manual adjustment of driver seat 

The manual adjustment is operated via the left front seat adjustment switch group.

The status of the left front seat adjustment switch group is read in directly by the left front door control unit. The left front door control unit sends the adjustment requests via interior CAN to the driver-side front seat adjustment control unit with memory and steering column. To adjust, hold down the respective switches on the left front seat adjustment switch group until the desired position is reached.

Depending on the request, the driver-side front seat adjustment control unit with memory and steering column actuates the following motors of the ESA [ESV] directly:

• Left fore/aft seat adjustment motor
• Left rear seat height adjustment motor
• Left front seat height adjustment motor
• Left head restraint seat adjustment motor
• Left backrest motor

Function sequence for manual adjustment of front passenger seat 

The manual adjustment is operated via the right front seat adjustment switch group.

The status of the right front seat adjustment switch group is read in directly by the right front door control unit. The right front door control unit sends the adjustment requests via the interior CAN to the passenger-side front seat adjustment control unit with memory. To adjust, hold down the respective switches on the right front seat adjustment switch group until the desired position is reached.

Depending on the request, the passenger-side front seat adjustment control unit with memory actuates the following motors of the ESA [ESV] directly:

• Right fore/aft seat adjustment motor
• Right rear seat height adjustment motor
• Right front seat height adjustment motor
• Right head restraint seat adjustment motor
• Right backrest motor

Function sequence for manual adjustment of left rear seat (with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7 with individual rear seats) 

The manual adjustment is operated via the left rear individual seat adjustment switch group.

The status of the left rear individual seat adjustment switch group is read in directly by the left rear door control unit. The left rear door control unit sends the adjustment requests via rear individual seat CAN to the left rear individual seat control unit. To adjust, hold down the respective switches on the left rear individual seat adjustment switch group until the desired position is reached.

Depending on the request, the left rear individual seat control unit discretely actuates the following ESA [ESV] motors:

• Left rear seat adjustment motor, fore/aft
• Left rear seat adjustment motor, rear seat height
• Left rear seat adjustment motor, front seat height
• Left rear head restraint seat adjustment motor
• Left rear backrest motor

Function sequence for manual adjustment of right rear seat (with code (ZS6) Special protection version FB6 or with code (ZS7) Special protection version FB7 with individual rear seats) 

The manual adjustment is operated via the right rear individual seat adjustment switch group.

The status of the right rear individual seat adjustment switch group is read in directly by the right rear door control unit. The right rear door control unit sends the adjustment requests via rear individual seat CAN to the right rear individual seat control unit. To adjust, hold down the respective switches on the right rear individual seat adjustment switch group until the desired position is reached.

Depending on the request, the right rear individual seat control unit directly actuates the following ESA [ESV] motors:

• Right rear seat adjustment motor, fore/aft
• Right rear seat adjustment motor, rear seat height
• Right rear seat adjustment motor, front seat height
• Right rear head restraint seat adjustment motor
• Right rear backrest motor

Function sequence for memory 

The memory function comprises the following subfunctions:

• Function sequence for storing seat position 
• Function sequence for calling up seat position 

Function sequence for storing seat position 

There are two options for storing the seat position:

• Hold the memory switch (S91s9, S92s9, S56s9 or S57s9) depressed and then press the memory 1, 2, 3 switch (S91s14, S92s14, S56s14 or S57s14) for the corresponding memory location.
• Press the memory switch for t > 100 ms and within 0.4 s ≤ t ≤ 3 s press the memory 1, 2, 3 switch for the respective memory position.

The status of the memory switch is read in voltage-coded by the corresponding door control unit.

The front door control units send this via interior CAN to the corresponding front seat adjustment control unit, which stores the current position of the seat.

The rear door control units send this via rear individual seat CAN to the corresponding rear individual seat control unit, which stores the current position of the seat.

Function sequence for calling up seat position 

To move to a stored seat position, the corresponding memory 1, 2, 3 switch has to be pressed and held until the stored end position is reached. If the switch is released, the adjustment procedure is terminated immediately.

Under the following conditions, the approach of a stored seat position is interrupted:

• Manual seat adjustment
• Manual outside mirror adjustment (driver only)
• Manual steering column adjustment (driver only)
• Request of a different stored seat position

The individual adjustment requests are prioritized by the respective front seat adjustment control unit or rear individual seat control unit. The ESA [ESV] is divided into two 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 respective front seat adjustment control unit or rear individual seat control unit, the adjustment request with the highest priority is performed.

The priorities are determined as follows:

Group 1:

• Backrest adjustment (high priority)
• Head restraint (average priority)
• Inclination adjustment (low priority)

Group 2:

• Fore/aft adjustment (high priority)
• Height adjustment (average priority)

Normalization function sequence 

Normalization is important for the assignment of the absolute adjustment position and the position recorded by the respective front seat adjustment control unit or rear individual seat control unit. Normalization must be performed during initial startup or in a denormalized condition.

To carry out the normalization procedure, it is necessary to move to the following mechanical end stops:

• Front end stop of fore/aft adjustment and backrest adjustment
• Downstop of inclination adjustment, height adjustment, and head restraint adjustment

For normalization, the corresponding switch in the seat adjustment switch group must remain actuated for t = 250 ms after the mechanical end stop has been reached.

Function sequence for position measurement 

The seat adjustment motors are equipped with Hall sensors. The signals of the Hall sensors are read in and evaluated by the respective front seat adjustment control unit or rear individual seat control unit.

Function sequence for antilock device 

With a Hall sensor recognized as faulty (t > 2 s), the corresponding adjustment function is switched off after t = 2 s by the respective front seat adjustment control unit or rear individual seat control unit. Switching on again in the same adjustment direction is only allowed after releasing the corresponding switch in the switch group, seat adjustment for t ≥ 2 s. Switching on again in the opposite direction is possible immediately.

Fault handling function sequence 

The respective front seat adjustment control unit or rear individual seat control unit checks the adjustment request for plausibility. Adjustment requests for the same adjustment function in an opposite direction (e.g. backrest adjustment forward//back simultaneously) are rejected. Correct adjustment requests for other adjustment functions remain unaffected.

	Electric seat adjustment (ESA [ESV]), location of components		GF91.29-P-0004-01G
	Block diagram of electric seat adjustment (ESA [ESV])		GF91.29-P-0004-03G
	Component description for rear SAM control unit with fuse and relay module	N10/2	GF54.21-P-6030G
	Left rear individual seat control unit, component description	N25/9 With model 463.236 with code (ZS6) Special protection version FB6 or code (ZS7) Special protection version FB7 with individual rear seats	GF91.29-P-5242G
	Right rear individual seat control unit, component description	N25/10 With model 463.236 with code (ZS6) Special protection version FB6 or code (ZS7) Special protection version FB7 with individual rear seats	GF91.29-P-5243G
	Component description of driver-side front seat adjustment control unit with memory	N32/1	GF91.29-P-5223G
	Component description of passenger-side front seat adjustment control unit with memory	N32/2	GF91.29-P-5224G
	Component description for left front door control unit	N69/1	GF72.29-P-4141G
	Component description for right front door control unit	N69/2	GF72.29-P-4142G
	Rear door control unit, component description	N69/3, N69/4 In case of model 463.236/237/270/271/341/346	GF72.29-P-6020G
	Electronic ignition/starter switch control unit (EZS), component description	N73	GF80.57-P-6000G
	Rear individual seats gateway control unit, component description	N93/6 With model 463.236 with code (ZS6) Special protection version FB6 or code (ZS7) Special protection version FB7 with individual rear seats	GF91.29-P-5238G
	Seat setting switch group component description	S91, S92	GF91.29-P-5206G