GF91.29-P-0009FL Electric Seat Adjustment (ESA (ESV)) Function

GF91.29-P-0009FL Electric Seat Adjustment (ESA [ESV]) Function
- with CODE (275) Electrically adjustable front seats with memory package

Function requirements, general
^ No engine start (circuit 50 OFF)
^ No undervoltage (U < 9.3 V)

The electronic ignition lock control unit (N73) transmits the circuit status and the rear SAM control unit with fuse and relay module (N10/2) the amplitude of the on-board electrical system via the interior CAN (CAN B).

Information on PRE-SAFE positioning function for passenger seat is given in the "PRE-SAFE" function description.

With code (494) USA version the code (275) is Electrically adjustable front seats with memory package, standard equipment.

Function description for electrical seat adjustment (ESE), general
The electrical seat adjustment is described as an example on the driver seat for left-hand drive vehicles; this applies analogously for the passenger seat.

On vehicles with code (275) Electrically adjustable front seats with memory package, the driver and passenger seat 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 move to the particular seat position.

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

Fault handling
The driver seat control unit checks the requests for seat adjustments 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
^ Head restraint presetting (only code (494) USA version, code (460) Canada version or code (498) Japan version)
^ Normalizing
^ Position measurement
^ Anti-lock device
^ Collision avoidance (on vehicles with code (287) Through-loading feature)

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

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

Priorities
The 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 adjustment 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, fore/aft adjustment
Priority average, height adjustment

The driver seat control unit actuates the following ESE motors according to 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

Additional function requirements
^ ESE 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) the corresponding memory location;
- Hold down left front memory function switch for t > 100 ms. Press left front memory switch 1, left front memory switch 2 or left front memory switch 3 within 0.2 s ≤ t ≤ 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 switch is read in by the left front door control unit via the left door LIN and transmitted to the driver seat control unit via the interior CAN. The driver seat control unit stores the current seat position.

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

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

Head restraint presetting (only code (494) USA version, code (460) Canada version or code (498) Japan version)

Additional function requirements
- Normalized seat fore/aft position
- Normalized head restraint height
- Function switched on via variant coding

Function sequence
The height of the head restraint is preadjusted automatically by the driver seat control unit depending on the seat longitudinal position according to the parameters programmed by development (coupling curve) 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 nominal curve is defined by the starting point and the inclination. Both values are adjusted via diagnosis at the factory.

One end stop (software stop) is programmed at the factory, if it is not programmed, the mechanical stop (hardware stop) is actuated. The head restraint presetting function can be switched on and off in the driver seat control unit via diagnosis and is coded after installation according to the country.

Head restraint adjustment using the control in the left front seat adjustment switch group and the setting of a stored position are independent of the head restraint adjustment function. If, in addition to the seat fore/aft adjustment, an additional manual adjustment is performed, the head restraint presetting function is not started or terminated. If the additional setting is terminated, the head restraint is again moved along according to the performance map when the seat fore/aft adjustment is active. This means, that the head restraint adjustment is interrupted only once during fore/aft adjustment and backrest adjustment. However, this is aborted on additional head restraint adjustment; the head restraint adjustment is resumed only upon receipt of the next adjustment request.

Abort conditions
The head restraint presetting function is interrupted in the event of:
- Manual head restraint adjustment

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 carry out the normalization procedure, it is necessary to drive 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 left front 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 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 seat control unit.

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

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

Collision avoidance (on vehicles with code (287) Through-loading feature)

Additional function requirements
- Normalization of the fore/aft adjustment, height adjustment, and backrest adjustment carried out
- Driving speed v < 5 km/h
- C. 15 off (driver seat only)

Function sequence
If the rear seat backrest is unlocked, the rear SAM control unit with fuse and relay module transmits a signal to the driver seat control unit via the interior CAN.
- Seat fore/aft adjustment is moved toward front to a certain position, if it is too far toward rear.
- Backrest is set up if it is too far inclined
- Seat height adjustment is moved upward if it is too far down
- Seat inclination adjustment is inclined toward front, if it is inclined to far toward rear

If the seat adjustment is set to a certain position, an adjustment toward the rear is only possible when the rear seat backrest is not locked (only with code (494) USA version).

If collision danger is present with the front seats when the rear backrest or the rear seat is folded down, the rear seat affected is moved. The fore/aft adjustment is moved toward front, if the seat is behind a certain position. The backrest is set up if it is inclined too far. The seat height adjustment is moved downward to a collision-avoiding position, if it is too far up.
- If the rear seat backrest is locked again, the seat remains in its current position. It is not moved automatically to the initial position
- The seat fore/aft adjustment is possible again over the entire adjustment range when the rear seat backrest is locked.

The rear seat backrest inclination 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).

Abort conditions
The collision avoidance with the rear seat function is aborted upon:
- Locking the rear backrest
- Actuation of left front seat adjustment switch group

After terminating the collision avoidance feature with the rear seat, the front seats can also be adjusted without limitation on vehicles with code (494) USA version.. On vehicles without code (494) USA version a manual adjustment into the collision zone during the collision avoidance function is possible. The seat adjustment is coded following installation depending on the country.

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