Seatbelt Pretensioners Designed to eliminate slack from the seatbelt. The more aggressive systems will pull the occupant back into seat. Introduced in late 70's, rare until 90's, now found in roughly 125 models from 29 manufacturers Variety of designs, most using pyrotechnics to trigger (a few are spring loaded). Typical design attaches the pyrotechnic to the rewind spool of the belt installation, usually located at the lower "B" pillar area. Volvo and Saab use the mid "B" pillar location. BMW and Ford Econoline Vans use a style that is installed at the transmission tunnel area with the tensioning mechanism attached to the seatbelt latch mechanism. See Rescuer's Guide to Vehicle Safety Systems for specific vehicle type and location information. Rear seatbelt pretensioners can be found on a few models, including Volvo and Audi Gas generator used is typically nitro-cellulose Most systems activated electronically, some use mechanical trigger device With very few exceptions, pretensioners are designed to deploy in front impacts (Mercedes triggers in front or rear impact) and precede the deployment of the airbag There are no visible identifiers for seatbelt pretensioners. When in doubt, carefully remove the "B" pillar trim cover and visually inspect Avoid cutting, pinching or otherwise disturbing the undeployed pretensioner To avoid creating or increasing injury to patient, remove or cut belt as soon as practical (once you have control of patient). Example of a Seatbelt Pretensioner mounted at the bottom of "B" Pillar. Example of a Seatbelt Pretensioner mounted in the middle of the "B" Pillar.