The system is turned off when the light is on so it will not deploy in a crash. There will be a diagnostic fault code stored in the computer that will indicate the circuit that needs further diagnosis. Probably the most common cause would be a broken clock spring. That is a wound-up ribbon cable in a plastic housing under the steering wheel. The horn and cruise control wiring go through it too and those systems will also eventually fail if the clock spring is at fault.
Even though the system has a lot of safeguards to prevent accidental deployment when anything is unplugged to work around it, a broken clock spring in effect circumvents that safety system. That leaves it vulnerable to being deployed from static electricity. We use a nine volt transistor battery to fire air bags for demonstrations. When you can feel a static shock when touching a door knob in your house, that is at least 3,000 volts. You can generate that by sliding across the seat in your car. That is how the air bag could pop accidentally, but the chances of that happening are very slim.
Tuesday, March 26th, 2013 AT 8:37 PM