Before I start
PLEASE be careful with these damm things:
1) They are saftey equipment and they do actually help unless its the old basic US system, in which case, hell yes, yank it out.
2) When they go off, BOY do they go. A sharp knock on the airbag controller or the airback internals in the hub can be enough. For example a frisbee'ed clio sterring wheel from a Phase 2 clio will fly about 50 foot if it goes off on landing. An airbar CAN break bones, people have been killed workign with them.
Check all the wiring as mentioned, check that the rings (if fitted) are clean and not corroded and the contacts are in good shape. Dont take the wheel apart unless you really have to. the book of lies has information on making the wheel safe should you need it.
Some systems have a battery pack, others use a cpacitor so they always have power. In the battery based systems the pack may have failed. TBH the best way to know whats died if its not a simple case of dirty rings, is to get the fault code read. There are ways to get the codes to 'blink out' on Autoliv system and you might find the info on the net.
The most common system IIRC is the Autoliv system but I dont know what Rover used. The Autoliv system typically has an ECU bolted to the floor pan or some solid, flat peice of bodywork someplace and will contain an accelerometer, this is why clocking the thing might set it off. There is sometimes a supplementory sensor and a remote storage pack. In the Autoliv system this lives in the steering wheel hub with the airbag. Signals are passed into the hub via rings and contact much the same way as the horn does on some cars. Inside the compressed airbag is an explosive charge that detonates with considerable force. If you have the hub apart there is normally a labelled connector you can seperate to isolate the charge. The charge is sensitive to shock and heat, remove the hub and put it someplace where it cant fall off.
The most common bodge I have seen is wiring the airbag lamp to the oil warning lamp, also seen this done for ABS lamps too.
This also applies to explosive seatbelt pretensioners too.
Incidentally most airbag ECUs record a lot of information about the crash, impact force and direction are almost always recorded, some even pull data from the car's ECU and continously store data one speed, brake application engine speed etc in a short loop. Full Impact control systems such as those used on more recent cars and very high end veichles such as the RRSC this may extend to minutes of data about all aspects of the car.
BTW I used to do a lot of work for Autoliv, TRL, MIRA and Klippan, can you tell? :)
