TENSIONER, Seat Belt: Operation

The seat belt tensioners and adaptive load limiter are deployed in conjunction with the dual front airbags by signals generated by the Occupant Restraint Controller (ORC) through the individual driver or passenger retractor (or sill end), tensioner (or anchor) or adaptive load limiter line 1 and line 2 (or squib) circuits. When the ORC sends the proper electrical signal to the tensioner and adaptive load limiter initiators, the electrical energy generates enough heat to initiate a small pyrotechnic Micro Gas Generator (MGG).

In sequence, the ORC activates the retractor tensioner, followed by the anchor tensioner. The adaptive load limiter on the retractor is activated only after both the retractor and anchor tensioners. The retractor tensioner gas generator drives the seat belt retractor spool causing slack to be removed from the front seat belt. The anchor tensioner gas generator pulls the buckle downward, causing the slack to be removed from the front seat belt. The ORC uses the adaptive load limiter to adjust the belt resistance, based upon impact data, to reduce the force of the tightened seat belt on the chest of the front seat occupant, reducing the potential for injuries.

Removing excess slack from the front seat belts not only keeps the occupants properly positioned for an airbag deployment following a frontal impact of the vehicle, but also helps to reduce injuries that the occupants of the front seats might experience in these situations as a result of harmful contact with the steering wheel, steering column, instrument panel or windshield.

The ORC monitors the condition of the seat belt tensioners and adaptive load limiters through circuit resistance. If any fault is detected, the ORC will illuminate the airbag indicator in the instrument cluster and store a Diagnostic Trouble Code (DTC). Proper diagnosis of the seat belt tensioner and adaptive load limiter initiators and squib circuits requires the use of a diagnostic scan tool and may also require the use of the Airbag Kit. Refer to the appropriate diagnostic information.