Description - SRS (RESTRAINT SYSTEMS) (page 4 of 6)

RESTRAINT SYSTEMS

75-6

DESCRIPTION AND OPERATION

Seat belt pretensioners

The seat belt pretensioners are located within the front seat belt anchors and are controlled by the DCU.  They are 
pyrotechnic devices that, when deployed, tighten the front seat belts.  This works in conjunction with the airbag 
module(s) to protect front seat occupants in the event of an accident.

The DCU regularly applies a test current to the seat belt pretensioner squibs to confirm continuity of the ignition 
circuitry.

The DCU is capable of detecting a short to ground, a short to battery and an open circuit for the squibs.  It will also 
identify if the configuration of the DCU differs from that actually fitted to the vehicle.

The DCU also stores the following additional information on each fault:

l

A count indicating the number of times the fault has occurred.

l

A start time and an end time for the fault to indicate duration of the fault.