Airbag Alarm Light

Recently I changed a turn signal switch on my VW Jetta 1994, and it turned out the new switch had a faulty horn/airbag connection (just not springin out enough), such that power was not being relayed - I figured this out when the horn would not blow, and on inspection I realized that there was a gap between the connector on the top of the switch and the horn. At the same time I realized that my problem was the signal relay, and not the switch. So I changed back to my old signal switch. The horn is now fine, but I have the airbag alarm light on. I am cannot think of anything I did wrong. So I am wondering whether the light could be coming on because of the initial error when there was no connection. Does anyone have such an experience, where the airbag signal keeps coming on even after the repair error is corrected, or does the alarm indicate a current error rather than a lingering memory of the error I had initially?

You need to take this to someone who works on air bag systems. Do not drive it,as the air bag could deploy. Its sounds like you messed up the clock spring. The air bag light is telling you its disabled. It may or may not be. Any time you have to work on a steering column and you have to remove a air bag it needs to be done by a pro.

Would the horn work if the clock spring was messed up? Perhaps I did not install it right, but I doubt that it is messed up - it is the same medium that delivers power to the horn, and the horn works.

I remember the manual instructed me to “center” the clock spring. I was not quite sure what that meant, and I was not sure I attained the result the manual described as centering. Can anyone describe centering, and also tell me if this is something I can correct if it is what I missed?

To answer myself, the horn does not rely on the clock spring for power.

I have however figured out through creative checks that my problem is not the clock spring. There is a full circuit from the clock spring connector below the steering wheel to the steering wheel itself. However the circuit is broken somewhere between the battery and the connector to the clock spring. I tested this by disconnecting the battery and putting the two cables together (watch out not to have your battery anywhere in the cicuit if you are going to try this), and confirming that there was sign of continuity at various other power outlets- Then I tested the airbag connector, there was no sign of continuity.

I cannot figure out where the circuit is broken - I am confident it is not just a wire, as there was not too much movement when handling this work. I do not see anything like an airbag fuse, or relay, the 2 things that I would have suspected after this diagnosis. Does someone know what would be broken? The one thing that keeps bells rindin in my mind is the “air bag control module”. Could this be my handicap?? What else, and what would be the remedy?

Back in '94, most cars 'bags worked like this…The 'bag module runs a self-test on the system at each power-up and if it checks out, it arms the system and turns off the 'bag light…If for any reason the self-test fails, the module blows an internal, non-replaceable fuse that disables the system. With the 'bag light on, the system is disabled. To repair, you must first cure whatever problem that caused the self-test failure (dealers have a special diagnostic tool to do this) AND THEN REPLACE THE BLOWN AIR-BAG CONTROL MODULE…If you guess wrong on your repair, if the fault remains, the new module will be instantly destroyed…($$$$) Sometimes you can find unblown modules in salvage yards…

On late model cars I’m told, the module can be reset after the fault is corrected…

Also, there is never any power in the 'bag firing circuit…But there must be continuity in that circuit back to the control module. I believe the bags are fired by a high voltage capacitor discharge system triggered by the control module…

Thumps up Caddyman.

I am not familiar with VWs, but I am familiar with Volvos and BMWs of that vintage. On those, if there has been an error, such as someone turning the key on when part of the system is unplugged, the airbag light will not reset itself after the problem is corrected. You have to reset it manually. No fuse, but you may need the proper tool that plugs in to the air bag system, reads the error codes, and clears them so the light will go out.

The bad news is that your air bag is 17 years old, and they don’t last forever. If it ever goes off, it may look like someone’s dirty laundry exploding out of your steering wheel rather than an intact bag inflating.

bwa ha ha ha … appreciated the humor Manolito! I do not look forward to dirty laundry flying in my face, leave alone the smack that I imagine would accompany it. Still I am not sure I am ready to let go this lovely fossil of mine.

Would you guys describe to me the location of the Airbag Control Module in this car? At least I would like to complete my diagnosis, i.e. to find out whether there is continuity up to the control module and none beyond.

Kimland your air bag will work fine once you have someone who is trained to work on them fix it. DO NOT TRY TO FIX THIS YOURSELF!! You could end up setting the bag off. Its not fun to be hit by one. I have seen arm’s and nose’s broke.

Manolito air bags are sealed, it will go off with the force intended. They will out last the car. Buy the way I set one off that came from the junkyard that had set in water on the floor of the car for along time. It went off just fine.

oldbodyman, I am the curious type. Even if I have to take it to a specialist I would like to do my diagnosis first. Besides the car is a fosil now, and I am not sure how much I am willing to throw at it from here. Knowing the exact problem would help me gauge the expected expense.

I do not doubt the danger you express in an exploding airbag. I have seen the stooges on youtube who launch them under their bottoms - not smart. But if it is going to explode on me, I suppose it will be the moment I connect power, and I know enough not to be seated in the car the first time power reaches the bag.

I don’t think the thing would go off in its present situation - the problem is that it may not go off even if I hit a wall. That is because there is no power to launch it. I already figured out that power is cut off somewhere far behind the stearing wheel. The clockspring is fine. I actually drove it for quite some time before disassembling again. So I am still interested in locating the airbag control module. I have seen several explanations that lead me to nothing.

You say you figured out the power is cut. But don’t know why its cut. That is a problem. It could be a cut wire… could be any reason. All it will take is power to get into the system and that power can come from any were. Just turning the key on can do it. Then its a airbag in your face. If you driving it wont be good. You will lose control. It is no way safe to drive a car with a airbag like this. If you must drive it take the airbag out till you have it fixed.

Airbags are not something to be curious about. By the way I had one go off in my shop on a hot dry day. It was not in the car,it was sitting on the floor sill in the steering wheel.

I have a Passat. It’s a known item on newer VWs, and a recall too (at least for my '06 Passat.) It’s the connector under the front seat. Give a VW dealer a call and ask.

oldbodyman, I get your point and will definitely take it seriously. Trombenik, thanks. I will be under that seat tomorrow serving my curiosity.

Eureka (not quite, but close): Found the location of the da’n thing: Highlighted very well here (but accessing it is another matter):

Another think I learn from the same source is that I might have set the airbag controller off when I scanned the airbag system with my OBD scanner (bought at $52 purposely for this scan). Ross-tech says " Please avoid scanning the airbag controller in these cars, unless you are prepared to buy a new one!". Time for the mechanic now - I have learned enough of this.

Since body shops deal with these things all the time, they are very familiar with them and may take pity on you before a dealer would…But you may reach the point where you put a little black tape over the light and drive on…