Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Mercedes Benz >> 2021 >> CLS450 Base >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Seats, Bunks, Restraint Systems - 257 Chassis 1 Of 3 >> Basic Knowledge >> Reversible Belt Tensioner, Basic Function - GF91.40-P-9890A

Reversible Belt Tensioner, Basic Function - GF91.40-P-9890A

Model all (CAR) 

G14474484Courtesy of MERCEDES-BENZ USA

Location 

The reversible emergency tensioning retractors are located at the bottom of the respective B-pillar.

Task 

The reversible belt tensioners have the task of tensioning the seat belt of the driver or front passenger seat in certain hazardous situations by actuating the integrated actuator motor. Securing the vehicle occupants in the seat in a more optimal fashion minimizes the consequences of a potentially impending accident. If the seat belt adjustment function is active, the seat belt slack is additionally reduced when the seat belt is fastened.

The reversible emergency tensioner retractors are connected to the network architecture of the vehicle.

The reversible belt tensioners process, for example, the following information:

The reversible belt tensioners process this information and actuate the integrated actuator motors accordingly. Faults and malfunctions are communicated to the driver.

IMPORTANT The seat belt tensioners are equipped with a mechanical acceleration sensor which locks the belt tension in the event of vehicle deceleration of over 0.3 g. Therefore, the seat belt can remain mechanically locked despite the emergency tensioning having ended.

  Component descriptions     
  Component description for front reversible emergency tensioning retractors Model 223
with code 460 (Canada version)
with code 562 (Driver seat belt buckle with integrated tensioning function)
Model 223
with code 494 (US version)
with code 562 (Driver seat belt buckle with integrated tensioning function)
GF91.40-P-4020A
    Model 243
with code 299 (PRE-SAFE®)
GF91.40-P-4020B
    Model 206
with code 299 (PRE-SAFE®)
GF91.40-P-4020C
    Model 297
with code 299 (PRE-SAFE®)
GF91.40-P-4020D