Hyundai Elantra MD/UD: Anchor Pretensioner (APT). Description 
and Operation - Seat Belt Pretensioner - Restraint - Hyundai Elantra MD 2010-2015 Service manualHyundai Elantra MD/UD: Anchor Pretensioner (APT). Description and Operation

Description

Front seat belt anchor pretensioner operates as well as belt pretensioner at the same time If it gets into its deploy condition after a collision. It is located at near anchor on front seat and it is an equipment to make up for the existing short stroke. Front seat belt anchor pretensioner is an auxiliary equipment to prevent the driver and passenger from breaking away doubly as seat belt is being pulled toward anchor side after a collision.
Never measure resistance of anchor pretensioner directly, current of measuring device may cause unexpected airbag deploy.

Installation
1. Remove the ignition key from the vehicle. 2. Disconnect the battery negative cable and wait for at least three minutes. ...