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

GF91.29-P-0009CA Electrical Seat Adjustment (ESA)
- with CODE (275) Memory package (driver seat, steering column, mirrors)
- with CODE (242) Electrically adjustable front passenger seat with memory

Function requirements, general
^ No engine start (circuit 50 OFF)
^ No undervoltage
^ Backrest not unlocked

When the backrest is unlocked, the backrest, head restraint, height and steering column adjustment are disabled. However, seat fore/aft adjustment is possible.

Electric seat adjustment function description, general
The driver seat on vehicles with code (275), and also the front passenger seat on vehicles with code (242), can be adjusted electrically as follows:
- Seat fore/aft position
- Backrest angle
- Seat height
- Seat inclination
- Head restraint height

Moreover, it is possible to store and call the corresponding seat positions (memory function).

On the driver-side, the positions of the outside mirrors and the steering column are also stored and retrieved via the memory function. The functions of the steering column adjustment or the outside mirrors are described in the separate function descriptions "Electrically adjustable steering column (ESC [EVL])" or "Electrical outside mirrors".

The electrical seat adjustment (ESE) is described on the driver seat for left-hand drive vehicle as an example, however this also applies for the front passenger seat.

Fault handling
The driver control unit checks the requests for seat adjustments it has received for plausibility. Adjustment requests for the same adjustment function in an opposite direction (e.g. backrest adjustment 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.

The ESE allows the following partial functions:
^ Manual adjustment
^ Saving and retrieving seat positions (memory function)
^ Head restraint presetting
^ Synchronizing
^ Position measurement
^ Anti-lock device
^ Rear easy entry (easy entry)
^ Collision avoidance with bench seat in rear (only model 207.3 (C207) with code (287) Through-loading feature)
^ Collision avoidance with draft stop (only model 207.4 (A207))

The PRE-SAFE positioning function of the passenger seat is described in the separate "PRE-SAFE" function description.

The easy entry/exit function is described in the separate "Easy entry/exit steering column adjustment" function.

The crash-active easy exit function is described in the separate "Triggering supplemental restraint system" function description

The function of the retractable rear head restraints (only 207.4 (A207)) is described in the separate function description "Soft top" in the subchapter "Comfort/open driving".

Manual adjustment
The manual adjustment is operated via the left front seat operation switch group (S22). The left front seat adjustment switch group is read via the left door LIN (LIN B5) by the left front door control unit (N69/1). The left front door control unit transmits the request from the left front seat adjustment switch group to the driver seat control unit (N32/1) via the interior CAN (CAN B). To adjust, hold down switches on left front seat adjustment switch group until the desired position is reached.

Priorities
The electrical seat adjustment is divided up into 2 groups and 3 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
Priority high, backrest adjustment
Priority average, head restraint
Priority low, inclination adjustment

Group 2
Priority high, seat fore/aft adjustment
Priority average, height adjustment

The driver seat control unit actuates the following ESE motors depending on the request:
- Driver seat fore/aft adjustment motor (M27/1)
- Driver seat height adjustment motor (M27/2)
- Driver seat inclination adjustment motor (M27/3)
- Driver seat head restraint adjustment motor (M27/4)
- Driver seat backrest inclination adjustment motor (M27/5)

Saving and retrieving seat positions (memory function)

Additional function requirements
- Electrical seat adjustment normalized

Store driver seat position function sequence
There are two button operation options for storing the seat position:
- Hold down left front memory function switch (S22s6) and then press left front memory switch 1 (S22s7), left front memory switch 2 (S22s8) or left front memory switch 3 (S22s9) for the corresponding memory location.
- Press left front memory switch function for at least 100 ms. Press left front memory switch 1, left front memory switch 2 or left front memory switch 3 within 0.2 s to 3 s for the corresponding memory location.

Successful storage of the seat position is acknowledged by the instrument cluster (A1) with an acknowledgment tone.

The status of the switches is read in via the left door LIN and transmitted to the driver seat front door control unit via the interior CAN. The driver seat control unit stores the current position of the seat.

Move to stored position, function sequence
To actuate the stored position, press left front memory switch 1, left front memory switch 2 or left front memory switch 3 until the desired end position is reached. If the switch is released, the adjustment procedure is terminated immediately.

Abort conditions
Moving to a stored position is interrupted during:
- Manual seat adjustment
- manual mirror adjustment (driver only)
- manual steering column adjustment (driver only)
- When other memory switches are pressed

Head restraint presetting

Additional function requirements
- Normalized seat fore/aft position
- Normalized head restraint height

Function sequence
The height of the head restraint is adjusted automatically by the driver seat control unit depending on the seat fore/aft position. If the seat is adjusted forward, the head restraint moves down. If the seat is adjusted rearward, the head restraint moves up. The head restraint is adjusted in stages.

The head restraint presetting can be switched on and off on the driver seat control unit via diagnosis and is coded using the software according to the country.

Synchronizing

Additional function requirements
- Circuit 15R ON

Function sequence
Normalization is important for the assignment of the absolute adjustment position and the position recorded by the driver seat control unit. Normalization must be performed during initial startup or in a denormalized condition. To normalize, actuate the following mechanical stops:
- Front stop of seat fore/aft adjustment and backrest adjustment
- Downstop of inclination adjustment, height adjustment, and head restraint adjustment

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

Upon successful normalization, the driver seat control unit switches off the corresponding seat adjustment motor.

The normalization procedure should be performed via diagnosis for initial startup. In this case, circuit 15R must be switched on.

An adjustment is denormalized, if the signal of the corresponding Hall sensor is not received. The Hall sensors are allocated to the particular adjustment motors. The denormalization procedure can also be performed via diagnosis.

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 control unit.

Anti-lock device
If a defective Hall sensor is recognized for t > 2 s, the corresponding adjustment function is switched off by the driver seat control unit.

Reactivation in the same adjusting direction is not permitted until the corresponding switch has been released for at least 2 s. Re-enabling in the opposite direction is possible immediately.

Rear easy entry (easy entry)

Additional function requirements
- associated vehicle door open or
- Circuit 15R or
- Circuit 15 ON and vehicle speed below 5 km/h

If, during the process, the function conditions are canceled, the head restraint movement continues until it is completed. Furthermore, the function is only started when no abort conditions are pending.

The precondition for the function is that the head restraint adjustment was normalized at the upper stop.

The left EASY-ENTRY system limit switch (S159/3) consists of two contact switches, backrest inclination switch contact switch and backrest release contact switch.

Function sequence
Pulling the backrest release handle mechanically releases the backrest and can then be folded forward. When unlocking, the backrest release contact switch in the left EASY-ENTRY system limit switch is actuated, which is read in by the driver seat control unit. Then the head restraint moves to the lower stop to prevent collision with the headliner.

When folding the backrest forward from the non-actuated state, the seat inclination switch contact in the left EASY-ENTRY system limit switch is actuated and read in by the driver seat control unit. Then the seat starts moving forward. If, during moving forward, the backrest is folded back, the seat moves back again.

The excess force limiter is active during forward movement of easy-entry. If pinching is recognized, the seat reverses toward the rear, however, only up to the rear EASY-ENTRY end position at maximum.

By pulling the backrest release handle, the backrest is unlocked in the front-most position and can be folded back and the backrest release contact switch actuated in the left EASY-ENTRY system limit switch. When folding back the backrest from the non-actuated state, the seat inclination contact switch is actuated. Then the seat starts moving backwards. The backrest returns to the initial position and locks in the folded-back position. If the backrest is folded forward again during backward motion, the seat again moves toward the front.

When the easy-entry function moves backward, the excess force limiter is active. If pinching is recognized, the seat reverses toward the front but not beyond the front end position of easy entry. After locking the backrest and reaching the initial position of the seat fore/aft adjustment, the initial positions of the head restraint and the seat cushion length, height adjustment and inclination are actuated again. Here the priorities observed according to the group category.

The left EASY-ENTRY system limit switch consists of two contact switches, backrest inclination switch contact switch and backrest release contact switch.

Combination signal if seat not locked correctly
Additional function requirements
- associated vehicle door closed and circuit 15 ON

or

- Circuit 15R ON and vehicle speed above 6 km/h

The driver seat control unit monitors whether the seat is correctly locked and sends a signal to the instrument cluster (A1), if necessary, in order to trigger a corresponding warning indicator.

Abort conditions
The easy-entry function is interrupted, when the Hall sensor for the head restraint is detected as defective

Collision avoidance with bench seat in rear (only model 207.3 (C207) with code (287) Through-loading feature)

Additional function requirements
- Normalization of seat fore/aft adjustment, height adjustment and backrest adjustment performed
- Vehicle speed below 5 km/h
- C. 15 OFF (driver seat only)

Function sequence
When the rear seat backrest is unlocked, this is detected via the left rear backrest inclination switch (S54/7) and right rear backrest limit switch (S54/8) by the rear SAM control unit with fuse and relay module (N10/2). The backrest inclination in the rear is recognized by the rear SAM control unit with fuse and relay module via the left rear backrest inclination switch (S54/5) and right rear backrest inclination switch (S54/6).

The rear SAM control unit with fuse and relay module then transmits a signal to the driver seat control unit and front passenger seat control unit (N32/2) via the interior CAN. The driver seat control unit and front passenger seat control unit evaluate the current seat adjustment and detect whether a collision hazard with the front seat is present when folding down the rear backrest. If a collision hazard with the front seat is present when folding down the rear backrest and rear seat, the driver seat control unit and front passenger seat control unit start the following measures:
- The seat fore/aft adjustment of the driver and front passenger seat is moved forward to a certain position if the latter is positioned too far to the rear
- The driver and front passenger side backrest are set up if they are inclined too far
- The seat height adjustment for the driver and front passenger seat is moved upward, if it is positioned too far down.

If the seat adjustment has been set in front of these particular positions, an adjustment towards the rear is only possible up to these respective set positions (only for code 494 USA version).
- If the rear seat backrest is locked again, the seat remains on its current position. It is not returned automatically to the initial position.
- The seat fore/aft adjustment is possible when the rear seat backrest is locked over the entire adjustment range.

Abort conditions
The collision avoidance function of the rear bench seat is interrupted when:
- Locking the rear backrest
- Actuating left front seat adjustment switch group

After interruption of the collision avoidance function with the rear bench seat, the front seats on vehicles with code (494) USA version, can be adjusted without limitation.

On vehicles with code (494) USA, it possible to adjust to the collision zone during the collision avoidance function with the rear seat bench. The seat adjustment is coded following installation depending on the country.

The rear SAM control unit with fuse and relay module monitors via the left rear backrest inclination switch (S54/7) and right rear backrest limit switch(S54/8), whether the rear backrest is locked correctly and, if necessary, transmits a signal to the instrument cluster (A1), to switch on a corresponding warning indicator.

To trigger the collision avoidance with the rear seat function again, the system must detect that the rear backrest has been locked again.

Collision avoidance with draft stop (only model 207.4 (A207))

Additional function requirements
- Normalization of seat fore/aft adjustment, height adjustment and backrest adjustment performed
- Function is activated via diagnosis

Collisions with the additional draft stop behind the front seats is possible in the event of a seat fore/aft adjustment toward the rear, a height adjustment downward and a backrest adjustment toward the rear. To prevent these, the adjustment ranges for seat fore/aft, height and backrest adjustment are limited in the driver seat control unit or in the front passenger seat control unit using characteristics maps. The characteristics map limit is adjusted depending on the height adjustment position. If two adjustments in the direction of the characteristics map limit are performed, both adjustments are ended. The rest position of the left front switch group, seat adjustment or right front switch group, seat adjustment (S23) must be recognized for additional adjustment.

Collision avoidance with active seat fore/aft adjustment toward rear
If the adjustment range limit is reached as per the characteristics map programmed in the driver seat control unit when making a seat fore/aft adjustment toward the rear, the backrest adjustment toward the front is activated for a specific backrest adjustment range. If the seat fore/aft adjustment is actuated further, the seat fore/aft adjustment is independently actuated to the next adjustment range limit. As long as the seat fore/aft adjustment is continuously actuated, this procedure alternates.

All parameters can be set via diagnosis. On vehicles with code (494) USA version, other parameters are coded. The differentiation of various parameter sets is to be performed by means of variant coding.

Collision avoidance with active backrest adjustment toward rear
If the adjustment range limit is reached as per the characteristics map programmed in the driver seat control unit when adjusting the backrest toward the rear, the backrest adjustment is stopped and, for a specific adjustment range, only the seat fore/aft adjustment toward the front (compensating movement) is actuated. If the backrest adjustment continues to be actuated, the seat fore/aft adjustment toward the front is activated as well as the backrest adjustment for a specific backrest adjustment range following this compensating movement. As long as the backrest adjustment is continuously actuated, this procedure alternates.

Collision avoidance with height adjustment
If the adjustment range limit is reached as per the characteristics map programmed in the driver seat control unit when making a height adjustment downward, the backrest adjustment toward the front is activated for a specific backrest adjustment range. If the height adjustment is actuated further, the height adjustment is independently actuated to the next adjustment range limit. As long as the height adjustment is continuously actuated, this procedure alternates.