Seatbelts: a guide to safely resetting and recalibrating

Education posted on 09/06/17

In the unfortunate event of a collision, seatbelts help protect the occupants from injury. During a collision, the airbag computer initiates the seatbelt igniter to ignite, activating the seatbelts and locking them into position around each occupant wearing the seatbelt. Once a seatbelt has been locked after a collision, it will need to be replaced, repaired and/or reset following the OEM recommendations.

Before the Repair

In a collision, the gas charge ignites, locking the seatbelt in place. Regardless of whether it’s the seatbelt retractor, or the buckle pre-tensioner, once activated, they will not work again.

All seatbelt parts must be inspected before the repair is started. All locked and disabled seatbelts must be replaced to restore this critical component of the vehicle’s safety system to factory condition. The SRS airbag module may also need to be reset or replaced. Repair shops should always follow OEM recommendations. Before beginning repairs, a pre-scan using the asTech™ device should be performed. The asTech™ report provides the in-shop technician with a complete list of the diagnostic trouble codes triggered as a result of the accident.

Once the scan is completed, the technician can determine which parts will need to be replaced, after a visual confirmation has been completed by the in-shop repair technician.

Replacements and Installation

Every seatbelt retractor is equipped with a complex mechanism that is engineered to lock during a collision. The components are accompanied by a small explosive apparatus known as the inflator. The inflator is triggered by the igniter, and must deploy in a timely matter.

The entire process is all controlled by sensors which communicate with the airbag system. In the event of a collision that causes the system to deploy, the sensor, igniter and the inflator will all need to be completely replaced in order to make the seatbelt operational once again. If the airbag warning light is on after a collision, the pre-tensioners, seat belt retractors, or buckles, will also need to be repaired or replaced following the OEM recommendations.

Each seatbelt is equipped with at least one two-pronged sensor that connects to the plug. This sensor will activate the gas charge in the seatbelt which causes it to deploy. A properly working sensor has a resistance between 2-3 Ohms. An improperly working sensor will either have no resistance, or will read something other than between 2-3 Ohms. If the resistance is not between 2-3 Ohms, the sensor or circuit is not working properly, and must be replaced or diagnosed to isolate the source of the concern.

Recalibration

Once all of the parts have been replaced, a completion scan with the asTech™ device will ensure that the seat belt safety system is working properly after the repairs have been completed.

Questions about replacing, repairing and resetting safety systems? Contact one of the experienced Master Technicians at asTech™.

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