Function description of seat belt extender - ra91001400506x(0506)
Model 140
In comparison to the model C 126 the seat belt extenders in the model C 140 have only one central control unit.
Automatic activation of the seat belt extender is accomplished when the following 4 conditions are fulfilled:
- Seat belt tongue not inserted into belt buckle (signal from belt buckle switch),
- Associated door has just been closed (signal from door contact switch),
- Ignition/starter switch just turned to position 1 or 2 (terminal 15R or 15) and,
- Door open/closed signal present from affected side.
The so-called door open/closed signal from the affected side is set (in the control unit memory), when the affected door is moved from the open to the closed position. This signal is set regardless of the ignition key position, time intervals and whether the belt buckle tongue is engaged. The door open/ closed signal is reset 60 minutes after the last change in the door contact or the ignition switch. This time limitation reduces the number of so-called ghost functions, i.e. unnecessary actuation of seat belt extender when front seat is not occupied.
Automatic activation of the seat belt extender starts the following cycle: The seat belt extender moves to its front most position, and then - without pausing - back approx. 25 mm (time control) to the so-called offering position. Here the seat belt extender arm remains for 30 s before it moves back to its rearmost position.
If the cycle is started automatically, the stored door open/closed signal is reset after expiration of the complete offering time of 30 s.
However, if one of the following actions takes place during this cycle before expiration of the offering time, the seat belt extender in question immediately moves back to its initial position and any door open/ closed signal set is not reset:
- Seat belt tongue on side associated with seat belt extender in question is inserted into belt buckle (signal from belt buckle switch),
- Door in question is opened (signal from door contact switch),
- Ignition/starter switch turned to position 0 (acts on both seat belt extenders).
If the seat belt extender is subjected to a counterforce when extending, the seat belt extender arm stops and moves back approx. 25 mm (time control), however, not farther than the rearmost position, to relieve the load and remains in this position for 1 s.
This operation can be repeated a maximum of 7 times when the counterforce is present for a longer period. If the foremost position is not reached after the eighth attempt, the arm moves back to its initial position.
If the seat belt extender arm does not actuate one of the following 3 micro switches
Extender arm extended switch (A10s2, A11s2),
Extender arm retracted switch (A10s1, A11s1),
Force limit switch (A10s3, A11s3) within 8 s when the motor is switched on, so-called total switch-off is actuated. This causes the seat belt extender arm to retract immediately to the stop (the motor (A10m1, A11m1) runs in the retract direction for 8 s when it was poled to run in the extend direction before expiration of the operating time limit of 8 s).
After such total switch-off the control unit (N42) does not send further signals of any type to the affected seat belt extender. The system can be reset after total switch-off by turning the ignition/starter switch from position 0 to 1.
Both seat belt extenders can be activated manually by momentarily pressing the seat belt extender switch (S17/17).
The left and right seat belt extenders have no mutual effect on one another, whatsoever.
Diagnosis is described in the Diagnosis manual Body, Volume 3.
Manual activation of the seat belt extender can be accomplished regardless of the ignition key position when the following two conditions are fulfilled:
- Seat belt tongue not inserted in seat belt buckle on side in question (signal from belt buckle holder).
- Door in question must be closed (signal from door contact).
When the previous conditions are fulfilled both seat belt extenders are activated.