GF91.29-P-0004LE Electric Seat Adjustment (ESA) Function
GF91.29-P-0004LE Electric Seat Adjustment (ESA) Function
- Front Seats
Function requirements, general
^ No engine start (circuit 50 OFF)
^ No undervoltage (U < 9.3 V)
^ No overvoltage (U > 16.0 V)
The EIS [EZS] control unit (N73) transmits the circuit status via interior CAN (CAN B).
Function description of electric seat adjustment (ESV [ESA]), general
The seat adjustment is described for the driver seat for a left-hand drive vehicle by way of example; this also applies analogously for the front passenger seat.
With the seat adjustment the front seats can be adjusted electrically as follows:
- Seat fore/aft position
- Backrest angle
- Seat height
- Seat cushion length
- Seat cushion 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 left front seat control unit (N32/1) checks the plausibility of requests received for seat adjustments. 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 electric seat adjustment enables the following subfunctions:
^ Manual adjustment
^ Storing and calling seat positions (model 221 with code (275) Memory package for electrically adjustment front seats or on model 216)
^ Head restraint presetting (only vehicles as of model year 2010/YoM 09 and vehicles with code (494) USA version, code (460) Canada version or code (498) Japan version)
^ Normalizing
^ Position measurement
^ Anti-lock device
^ Adjustment possibility for passenger seat by driver with left front seat operation switch group (S22) (Courtesy function) (model 221 with code (275) Memory package for electrically adjustable front seats or on model 216)
^ Adjustment option of front passenger seat from the rear via the right rear seat operation switch group (S55/2) (only model 221 with code (223) Rear bench seat with electrically adjustable outer seats with PRE-SAFE positioning function for outer seats and outer head restraints)
^ Easy entry function (rear easy entry) (only model 216)
^ Non-occupied position of passenger head restraint
Manual adjustment
The manual adjustment is operated via the left front seat operation switch group (S22). The left front seat operation switch group is read in via front door LIN (LIN B1) on left by the left front door control unit (N69/1) (model 221) or by the left door control unit (N69/1) (model 216). The left front door control unit transmits the requests from the switch group via interior CAN to the left front seat control unit, which actuates the following ESA [ESV] motors depending on the request.
- Left front seat fore/aft adjustment motor (M27/1)
- left front head restraint motor (M27/4)
- Left front backrest angle adjustment motor (M27/5)
- left front seat cushion fore/aft motor (M27/8)
- left front seat cushion inclination motor (M27/9)
- left front seat height adjustment motor (M27/10)
To adjust, hold down the switches of left front seat operation 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 left front seat control unit, then the adjustment request with the higher priority is performed.
The priorities are determined as follows:
Group 1
Priority high, fore/aft adjustment
Priority average, inclination adjustment
Priority low, up/down adjustment
Group 2
Priority high, backrest adjustment
Priority average, height adjustment
Priority low, head restraint adjustment
Storing and calling seat positions (model 221 with code (275) Memory package for electrically adjustment front seats or on model 216)
Additional function requirements
^ Normalized electric seat adjustment
Store driver seat position function sequence
There are two button operation options for storing the seat position:
- The memory switch (S22s6) is held pressed and then memory 1 switch (S22s7), memory 2 switch (S22s8), or memory 3 switch (S22s9) is pressed for the particular memory.
- Press the memory switch for t > 100 ms.
Within 0.2 s ≤ t ≤ 3 s, memory 1 switch, memory 2 switch, or memory 3 switch must then be pressed for the particular memory.
The status of the switch is read in by the left front door control unit via the left front door LIN and transmitted to the left front seat control unit via interior CAN. The left front seat control unit stores
the current seat position. Successful storage of the seat position i acknowledged by the instrument cluster (A1) with an acknowledgment tone. The instrument cluster receives the information via the central CAN (CAN F) from the central gateway control unit (N93), which receives the information from the particular seat control unit via interior CAN.
At the same time as the driver seat position is saved, the position of the steering column, the outside mirrors and, with code (432) Left and right dynamic multicontour seat or code (409) Left/right front multicontour seats, also the air pressures of the contour cushions are saved.
Automatic storing
When the engine is switched off (as from circuit 15C) and the driver door is closed, the current setting for the driver seat and the position of the steering column and outside mirrors are automatically stored (last driving position).
Move to stored position, function sequence
To be able to move to a stored position, memory 1 switch, memory 2 switch, or memory 3 switch must be held pressed until the stored end position has been reached. If the switch is released, the adjustment procedure is terminated immediately.
At the same time as the driver seat is moved to the stored position, the steering column and outside mirrors move to their assigned stored positions. With code (432) Left and right dynamic multicontour seat or code (409) Left/right front multicontour seats, the stored air pressures for the contour cushions are also adjusted.
Abort conditions
Moving to a stored position is interrupted during:
- Manual seat adjustment
- Manual mirror adjustment (driver only)
- Manual steering column adjustment (only driver)
- When additional memory switches are pressed
Head restraint presetting (only vehicles as of model year 2010/YoM 09 and vehicles with 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 sequence
The height of the head restraint is adjusted automatically by the left front 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 function can be switched on and off in the left front seat control unit via diagnosis and is coded after installation 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 left front seat control unit. Normalization must be performed during initial startup or in a denormalized condition.
The following mechanical end stops have to be moved to for the normalization procedure:
- Front end stop of fore/aft adjustment and backrest adjustment
- Downstop of head restraint adjustment
- Upper stop of height adjustment and inclination adjustment
- Rear end stop for up/down adjustment
For normalization, the corresponding switch in the left front seat operation switch group must remain actuated for a further t = 250 ms after the mechanical end stop has been reached. Upon successful normalization, the left front seat control unit switches off the respective 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 left front 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 left front 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.
Adjustment possibility for passenger seat by driver with left front seat operation switch group (S22) (Courtesy function) (model 221 with code (275) Memory package for electrically adjustable front seats or on model 216)
By actuating the left or right seat operation selection switch (S22s10) in the left front seat operation switch group, the adjustment request is read by the left front door. control unit via the front door LIN and relayed to the right front seat control unit (N32/2) via the interior CAN. After actuating the left or right seat adjustment selection switch, the front passenger seat adjustment is active for 10 s and this is indicated by the light emitting diode (LED) in the left or right seat adjustment selection switch.
The following adjustment functions are possible:
- Seat fore/aft position
- Backrest angle
- Seat height
- Seat cushion length
- Seat cushion inclination
- Head restraint height
Adjustment option of front passenger seat from the rear via the right rear seat operation switch group (S55/2) (only model 221 with code (223) Rear bench seat with electrically adjustable outer seats with PRE-SAFE positioning function for outer seats and outer head restraints)
S55/2s10By actuating the front or rear seat adjustment selection switch in the right rear seat operation switch group, the adjustment request is read in over the rear door LIN (LIN B2) on the right by the right rear door control unit (N69/4) and sent over the interior CAN to the right front seat control unit. After actuating the left or right seat adjustment selection switch, the front passenger seat adjustment is active for 10 s and this is indicated by the light emitting diode (LED) in the front or rear seat adjustment selection switch.
The following adjustment functions are possible:
- Seat fore/aft position
- Backrest angle
- Seat height
- Head restraint height
Adjustment requests from the right front door control unit have priority over requests from the left front door control unit or right rear door control unit.
Easy entry function (rear easy entry) (only model 216)
Additional function requirements
^ Front seat normalized
^ Easy entry/exit inactive (for driver seat)
Moving to entry position
When pulling the backrest release handle, the current seat position is stored automatically as initial position. The head restraint then moves to the lower stop to avoid any collisions with the headliner. Folding the backrest forward out of the reclining position actuates the left front seat backrest angle microswitch (S91/1) and this in turn then initiates the fore/aft movement of the seat toward the front.
After reaching the end position, the fore/aft movement of the front seat is stopped and the backrest adjusted, if necessary. If the backrest was set to a relatively "flat" position, it is adjusted forward to increase the entry area and to ensure that the rear passenger's legs are not trapped when it is folded back. If the backrest was set to a relatively "steep" position, it is moved backwards to enable it to be locked in the folded forward position.
Moving to initial position
Pulling the backrest release handle mechanically releases the backrest again, which can then be folded backward. The backrest angle microswitch closes and the seat adopts the previously stored position. The backrest is mechanically locked again in the folded back position. The excess force limiter is active when the seat is moving backward. If any obstruction is detected, the front seat moves forward again.
Non-occupied position of passenger head restraint
Additional function requirements
^ Circuit 15R ON
^ Normalized head restraint height
^ The function is activated via diagnosis
The non-occupied position of the front passenger head restraint is described for the front passenger seat for left-hand drive vehicles by way of an example, but this also applies for the front passenger seat for right-hand drive vehicles.
A non-occupied position of the passenger head restraint will see the head restraint move to the lower stop, in order to improve the rear passenger's view to the front. When the passenger side seat is occupied the head restraint moves back to its original position. The function is only executed by the passenger-side seat control unit. The Easy-Entry function (model 216 only) has priority. If the Easy-Entry function is active or the backrest is unlocked and with an existing fault in the right front seat backrest angle microswitch (S92/1) (model 216) there is no head restraint adjustment because of this function.
The function is triggered as a function of the front passenger seat belt buckle status, the vehicle speed the seat occupied signal. The right front seat control unit (N32/2) receives these signals via the interior CAN. An ongoing function is interrupted as soon as the Easy-Entry function (model 216 only) is initiated.
The seat changes to the "occupied" state if:
- The seat has been recognized as occupied for longer than 2 s,
- The seat belt buckle is recognized as inserted.
The seat changes to the "not occupied" state if:
- The seat has been recognized as not occupied for longer than 1 s, the seat belt buckle has been recognized as not fastened and the vehicle speed is below a certain threshold.
For detailed information on seat occupied recognition and on the seat belt buckle status see supplemental restraint system (SRS) system description.
Abort conditions
The not-occupied position of the front passenger head restraint is interrupted with:
- Circuit 15R OFF
- Manual seat adjustment of front passenger seat
- Manual seat adjustment of front passenger seat from the rear via the right rear seat operation switch group (only model 221 with code (223) Rear bench seat with electrically adjustable outer seats with PRE-SAFE positioning function for outer seats and outer head restraints)
- Seat adjustment via memory (move to position)
- Saving of front passenger seat position
- Easy entry function (only model 216)
- Hall sensor for front passenger head restraint defective
