Seat Belt Systems: Testing and Inspection

CONTINUOUS LOOP SHOULDER/LAP BELT TEST

NOTE: The vehicle is equipped with two front and two rear seat belt systems, which are dual sensitive (i.e., will lock when webbing is extracted quickly or when the vehicle is braking, cornering or accelerating heavily).

TESTING THE WEBBING SENSOR
To establish that the webbing sensor is working, the vehicle should be stationary and level. The webbing coming from the retractor must be grasped firmly and pulled out quickly. The retractor should lock up and prevent further webbing payout after a few inches of initial extraction.

TESTING THE VEHICLE SENSOR
1. Buckle up and drive the vehicle to a safe test area. If the front and rear passenger belts are to be tested, a passenger should be buckled into the belt that requires testing.

NOTE: The seat belt should not be fully extended to preclude possibility of a false feeling (full extension vs. lockup).

2. Accelerate to a speed of approximately 5 mph (8 km/h). The driver should inform the passenger that he is prepared to make a severe brake application. At this time, both driver and passenger should grasp their respective shoulder harnesses and prepare to lean forward slightly at the moment the brake application is made.
3. The driver will make a maximum brake application without tire skidding. The maximum brake application should be on dry concrete or equivalent hard road surface.) The driver and passenger should lean slightly into the shoulder harness. At this point, the belts should lock up without webbing payout.
4. If there is a lockup of the shoulder strap, the seat belt assembly is functioning properly. Should either or both retractors fail to lock up at 5 mph (8 km/h), the test must be repeated at 15 mph (24 km/h).
5. If any of the front or rear shoulder belts do not lock up at 15 mph (24 km/h), the vehicle is to be returned for replacement of the malfunctioning belt and retractor assembly.

NOTE: If the retractor of a new seat belt assembly has been bolted into a damaged or distorted mounting area, the new retractor may be mounted at an incorrect installation angle. This will cause the vehicle sensor to activate prematurely and not allow webbing payout. If this is the case then the sheet metal should be reworked to the correct shape and the retractor reinstalled.

NOTE: A 17 mm socket wrench, or equivalent, should be used for removal and installation of seat belt bolts on all seat belt assemblies.