Seat Belt Systems: Description and Operation

GF91.40-P-2001LA Seat Belt Lock System Function

General function requirements
^ Circuit 15 On

Belt lock system in general
The mechanical automatic belt retractors for the front seats are equipped with a belt lock system. The belt extension is blocked depending on the vehicle acceleration and vehicle inclination.

Belt lock system function sequence
The vehicle-sensitive belt lock sensor (A60) monitors the vehicle's current acceleration and incline angle continuously.

If one of these variables exceeds the permissible limit value (vehicle acceleration > 0.45 g or vehicle inclination > 27°), the vehicle-sensitive belt lock sensor sends a signal to deploy the belt lock to the left front seat control unit (N32/1) and to the right front seat control unit (N32/2). The respective seat control unit then actuates the left front seat belt lock relay (K18/2) and right front seat belt lock relay (K18/3) to lock the respective belt extension.

The front seat control units receive a constant signal from the vehicle-sensitive belt lock sensor and as a result they can detect any faults in the actuation circuits for the solenoids. The fault message is displayed in the instrument cluster (A1).