Function of protective devices

P91.29-0248-06

M27 Left front ESA motor group (with memory)

M28 Right front ESA motor group (with memory)

N32/1 Left front ESA control module (with memory)

N32/2 Right front ESA control module (with memory)

N32/5 Left seat proximity control module

N32/6 Right seat proximity control module

Automatic backrest locking

The locking of the integral seat backrest is monitored by a safety package.

If the safety package recognizes a seat backrest is not locked when the ignition is switched on and the door is closed, the "Backrest adjustment forwards" function is triggered via the front ESA control module (with memory) (N31/2 and N32/2).

Only the "Backrest adjustment" function is actuated during automatic backrest locking. All other functions are disabled.

The function is switched off if after approx. 20 seconds neither the backrest is locked nor the adjustment travel limit is reached. Normal adjustment is possible again after this.



If the backrest is not locked, first an indicator lamp in the instrument cluster flashes for approx. 5 seconds and then comes on permanently.

An audible warning signal by means of a warning buzzer installed in the seat also sounds for approx. 20 seconds.

Both signals are activated independently of belt use and seat occupation.

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Pre-lock cut-out

To restrict the number of mechanical hard stops of the seat, a pre-lock cut-out is stored in the front ESA control module (with memory) (N32/1 and N32/2).

For this the "Positions" of the mechanical end stops are stored when first approached. Any adjustment function triggered is then switched off at least before the mechanical end stop.

The stored "Positions" of the mechanical end stops are erased,

 after 255 operations of the respective adjustment function,

 by interrupting the voltage supply (terminal 30) of the control module or

 when the minimum distance between the two stored cut-out points is not reached.

The minimum distance is 90% of the total adjustment travel.

The "Positions" are stored again the next time the respective end stops are approached.

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Evading movements

To prevent a collision between the backrest and soft top compartment during large adjustment travels and steep backrest inclination, a seat proximity control module (N32/5 and N32/6) is installed.

Once the minimum distance between the seat backrest and soft top compartment is not achieved, the respective adjustment function (basic function) is stopped and an appropriate auxiliary function is performed:

Case: Basic function: Auxiliary function:

a) Fore/aft adjustment backrest adjustment

backwards forwards

b) Backrest adjustment fore/aft adjustment

backwards forwards

c) Height adjustement at backrest adjustment

rear down forwards

The basic function is switched on again once the minimum distance is exceeded.

In case c), once the basic function is switched on, the auxiliary function is only performed for a maximum of one second. If the minimum distance is not reached again when the basic function is continued, the process is repeated.

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Evading movements when adjusting a stored seat position

(with memory feature and memory package only)

If the seat proximity control module (N32/5 and N32/6) is active, the respective adjustment function stops and movement is started away from the seat proximity control module.

Only when this movement is finished is the original movement switched on again.

If the seat proximity control module (N32/5 and N32/6) is activated when the "Backrest back" and "Fore/aft adjustment forward" are adjusted at the same time, the backrest adjustment is stopped and the fore/aft adjustment runs on its own for approx. 1.6 seconds. The backrest adjustment is switched on again after this.

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Locking protection

The locking condition is recognized if a seat adjustment function is triggered and the front ESA control module (with memory) (N32/1 and N32/2) does not receive any Hall sensor pulses.

If a motor of the front ESA motor group (with memory) (M27 and M28) locks during an adjustment function, the motor is switched off after approx. one second.

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Adjustment in the same direction is only possible again if the corresponding switch is not operated for approx. 3 seconds. Adjustment in the opposite direction is possible immediately.

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