Safety System Repair Basics (Part 4 of 5) Accident with Seat Belt Pretensioner Deployment Only

| April 24, 2015

Component Replacement and Inspections


The seat belt pretensioners (driver and passenger) consist of a housing, seat belt retractor (located in the B-pillar), seat belt anchor (located on the floor), seat belt webbing, an initiator and a canister of gas-generating materials. The initiator is part of the seat belt pretensioner deployment loop.

When the vehicle is involved in a collision of sufficient force, the inflatable restraint sensing and diagnostic module causes current to flow through the seat belt deployment loops to the initiator. Current passing through the initiator ignites the material in the canister producing a rapid generation of gas. The gas produced from this reaction deploys the seat belt pretensioners which removes all of the slack in the seat belts.

Depending on the severity of the collision, the seat belt pretensioners may deploy without the frontal air bags deploying, or they will deploy immediately before the frontal air bags deploy. Each seat belt pretensioner is equipped with a shorting bar that is located in the connector of the seat belt pretensioner. The shorting bar shorts the seat belt pretensioner circuitry to prevent unwanted deployment of the seat belt pretensioner when the connector is disconnected.

After a collision involving driver/passenger Seat Belt Retractor or Anchor Pretensioner deployment, replace the following components:

  • Driver and Passenger Inflatable restraint seat belt anchor pretensioner and/or retractor pretensioner
  • Inflatable Restraint Sensing and Diagnostic Module (SDM), if the Inflatable Restraint Sensing and Diagnostic Module has set DTC B0052 and will not clear


Perform additional inspections for any damage and repair or replace each component as needed on the following components.

  • Mounting points or mounting hardware for the Inflatable Restraint Sensing and Diagnostic Module
  • Mounting points or mounting hardware for the Seat Belt Anchor Pretensioners
  • Mounting points or mounting hardware for the Seat Belt Retractor Pretensioners

Tags: , , , , , , , , , ,

Category: The Technical Side