Component Description For Front Reversible Emergency Tensioning Retractors - GF91.40-P-4020RF

Model 205, 253 

with code 299 (PRE-SAFE®) 

Shown: Model 205.0 

Fig 1: Front Reversible Emergency Tensioning Retractors Components Location - Model 253 With Code 299 (Shown: Model 205.0)

Courtesy of MERCEDES-BENZ USA

Location 

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

Tasks 

The reversible emergency tensioning retractors have the task of tensioning the seat belt of the driver or front passenger seat in certain hazardous situations by actuating an integrated actuator motor. This reduces the consequences of a possible subsequent accident. If the seat belt adjustment function is active, the seat belt slack is additionally reduced when the seat belt is fastened.

The tasks are subdivided as follows:

• Reading in of signals 
• Evaluation of input factors 
• Transmitting signals 

Reading in of signals 

The following signals, among others, are read in via the user interface CAN (CAN HMI):

• Status of driver seat belt buckle switch (S68/3)
• Status of front passenger seat belt buckle switch (S68/4)
• Crash signal
• PRE-SAFE® status
• PRE-SAFE® stage
• Status of seat belt adjustment function

The functions that use these signals are described in the individual function descriptions (see block diagram or function schematic).

Evaluation of input factors 

The read-in input factors are evaluated by the integrated microprocessor whereupon the integrated components are actuated and the CAN signals issued.

Transmitting signals 

The reversible emergency tensioning retractors send e.g. the request to display a fault message via the user interface CAN to the instrument cluster (A1).

The functions that use these signals are described in the individual function descriptions (see block diagram or function schematic).