ML 350 (163.157) V6-3.7L (112.970) (2004)
Seat Belt Tensioner: Description and Operation
GF91.40-P-4001-04A Rear Emergency Tensioning Retractor, Function
GF91.40-P-4001-04A Rear Emergency Tensioning Retractor, Function
Rear seat belt emergency tensioning retractor, left and right
In the event of a rear end collision or front end collision (crash with min. actuation stage 1) the restraint system control module (N2/7) activates the
emergency tensioning retractors in the rear of the vehicle. The left rear ETR squib (R12/6) and the right rear ETR squib (R12/7) are simultaneously
ignited electrically by the restraint systems control module (N2/7).
The emergency tensioning retractors can only be actuated once. In the event of a second crash the mechanical protective function of the seat belt is
maintained. Without emergency tensioning retractor the reel shaft is locked mechanically by the locking system so that it takes up the entire force of the
belt.
The left and right rear emergency tensioning retractors are only activated in the event of a crash when the corresponding seat belts are actually buckled.
The switch states of the left rear seat belt buckle and seat belt wear convenience switch (S68/11) and right rear seat belt buckle and seat belt wear
convenience switch (S68/12) are checked directly by the restraint systems control module (N2/7).
The emergency tensioning retractors in the rear of the vehicle are not equipped with a belt force limitation feature.