Air bag failure is pretty much unheard of. The shorting bars are only in places that a lack of them would leave the bag susceptible to static discharge. That means you'll find one inside the connector on the back of the air bag assembly, but one isn't needed on the wire coming out of the clock spring. Similarly, the wire traveling up the steering column is plugged in either on back of the clock spring or at the base of the steering column. In that connector, if you unplug it, the top half has the terminals going to the air bag, so that will have the shorting bar. There's no need for a shorting bar on the lower part that goes to the computer module.
With the air bag set aside, you can safely measure continuity of the squib, or "initiator" wire. If you have tilt steering wheel, moving it repeatedly can cause those wires to break and make intermittent contact. Be sure to move the steering wheel up and down while taking those readings.
If the car was crashed in the past, usually the connector at the back of the air bag melts from the heat of the burning rocket fuel, and that requires replacing the clock spring. If it didn't melt, and someone reused it, check for deformed terminals that aren't making good contact. Be aware too that around that time period, a lot of fault codes for the squib referred simply to a "shorted OR open" condition. A melted or deformed plastic finger on the connector could fail to move the shorting bar away from the terminals. That would cause a shorted condition. To measure for a shorted squib with an ohm meter you have to push the shorting bar away from the terminals.
Also, most Air Bag Computers will shut the system down permanently during that key cycle when an intermittent problem is detected. The problem may correct itself during 99 percent of the time, including while you're taking measurements. In that case, the fault code is all you have to go on This is where we just replace the clock spring as it's the only logical cause of an open squib. We will guess wrong so seldom that in those rare cases, the additional time we need for diagnostics is tiny compared to the time we didn't waste on all the other cars.
Saturday, June 4th, 2016 AT 2:24 PM