Knee Airbag
| Refer to COMPONENT INDEX . |
In vehicles manufactured for the North American market, the front airbag system also includes a driver KAB that is located just below the steering column, behind the instrument panel steering column opening cover. In vehicles manufactured for EMEA markets the KAB is optional equipment. This airbag is also a passive, inflatable SRS component and vehicles with this equipment can be readily identified by the AIRBAG logo molded into the steering column opening cover on the instrument panel just beneath the steering column.
The KAB can help prevent leg injuries during an impact event. A molded thermoplastic KAB deployment door, located below the dashboard, is the most visible part of the KAB. The housing contains the airbag inflator. The airbag inflator is a single-initiator and the two units are sealed within the KAB housing. EMEA vehicles can be equipped optionally with driver knee airbags. North American vehicles are always equipped with driver knee airbags.
When the ORC sends the proper electrical signals to the initiator, the electrical energy generates enough heat to initiate a small pyrotechnic charge, which in turn ignites chemical pellets within the inflator. Once ignited, these chemical pellets burn rapidly and produce a large quantity of inert gas. The inflator is sealed to the airbag cushion and a diffuser in the inflator directs all of the inert gas into the airbag cushion, causing the cushion to inflate.
As the cushion inflates, the KAB deployment door will split at predetermined tear seam lines concealed on the underside of the door, then the door will fold open and out of the way. The cushion protects the lower extremities of the vehicle driver and helps to keep the seat occupant properly positioned for the driver airbag deployment during a frontal impact collision. Following an airbag deployment, the KAB cushion quickly deflates by expelling the inert gas through the loose weave of the fabric.
The KAB is deployed by an electrical signal generated by the ORC through the KAB squib circuits to the initiator in the airbag inflator. When the ORC sends the proper electrical signal to the initiator, the electrical energy generates enough heat to initiate a small pyrotechnic charge which, in turn ignites chemical pellets within the inflator.
Once ignited, these chemical pellets burn rapidly and produce a large quantity of inert gas. The inflator is sealed to the back of the airbag housing and a diffuser in the inflator directs all of the inert gas into the airbag cushion, causing the cushion to inflate. As the cushion inflates, the KAB cover will split at predetermined breakout lines, then fold down out of the way. Following an airbag deployment, the airbag cushion quickly deflates by venting the inert gas towards the instrument panel through vent holes within the fabric used to construct the back panel of the airbag cushion.
Some of the chemicals used to create the inert gas may be considered hazardous while in their solid state before they are burned, but they are securely sealed within the airbag inflator. Typically, all potentially live pyrotechnic or hazardous chemicals are burned during an airbag deployment event.
The inert gas that is produced when the chemicals are burned is harmless. However, a small amount of residue from the burned chemicals may cause some temporary discomfort if it contacts the skin, eyes, or breathing passages. If skin or eye irritation is noted, rinse the affected area with plenty of cool, clean water. If breathing passages are irritated, move to another area where there is plenty of clean, fresh air to breath. If the irritation is not alleviated by these actions, contact a physician.
The ORC monitors the condition of the knee airbag through circuit resistance. If any fault is detected the ORC will illuminate the airbag indicator in the instrument cluster and store a DTC. Proper diagnosis of the KAB initiator and squib circuit requires the use of a diagnostic scan tool and may also require the use of the Airbag Kit. Refer to the appropriate diagnostic information.
The KAB cannot be repaired, and must be replaced if deployed, ineffective, or in any way damaged. Following a KAB deployment, the KAB and the steering column opening cover must be replaced.