940 Airbag reinstallation

My volvo 940 celebration has been off the road for a while, needing a few bits (tyres, brakes etc). Now i'm in a position to get it back on the road. However, before taking it for its annual MOT (I'm UK Based), i noticed the horn wasn't working. Some googling suggested wires behind the airbag, so i disconnected the battery and removed the airbag. I managed to get the horn working, and reassembled the airbag and screwed it all back in as it was.

Now i have an SRS light on the dash. I have tried disconnecting the battery for a period of time, i have tried taking out and reinstalling the airbag again, and still i have this SRS light.

I can't move the car to a garage as it has no road tax or MOT currently, and i can't take it for MOT as the SRS light is on and it would fail the test.

I have googled extensively on how to extinguish the light with little success apart from the fact i might need some software and a cable.

My car does have the OBD2 port in the armrest but from what i understand, only very few readers will actually work with this?

Can anyone help me before i'm forced to break the car up for bits? hich is a shame as its a good one and i was in the process of getting it back to its former glory, but i can't just have it sitting around abandoned so i either need to fix it or get it sold to someone who can. I dont want to sell it, however, if theres nothing more i can do, i have no choice.

It needs four tyres and front brake pads (which i was getting done before all this happened!) apart from that, its running great now.

Many Thanks
James

As I'm really only aware of the regs in the UK anecdotally... what is it that would cause it to fail? The light being on in their face or...?

It's unlikely that they'll have a way to test the system but then again... I'm a 240 person. My advice would be to pull the bulb to get you over the hurdle or the wiser advice is to have it towed.

Let me be very clear though... messing with a bomb that's a foot away from your face isn't exactly childs play...

So no way you can read the SRS fault code?
Very likely the problem is in the clockspring (coiled driver airbag cable). In that case you can install 2-3 OHM resistor into the plug that connects into the clockspring. That will fool the control module to think that driver side airbag is connected and the circuit is fine. The warning light will work as it should: light up with key on and turn off once the car is started.
You can get the SRS bypass resistor on e-bay for cheap if you don't feel like looking for it in the electronics store.

Correct if the SRS light remains on when the car I'd started, it will fail the test.

There is literally the one cable to plugin so I'm not sure where I'm going wrong. From what I've read the horn connections behind the airbag going bad is quite common so I didn't think I would have much problem fixing that but it seems I was wrong as I've fixed the horn but now struggling with the airbag.

Pull the bulb for the inspection and then fix it?

You probably didn't lock down the clockspring when you pulled it and it unravelled. It's tough to spin em back to the proper tension. I couldn't tell you how many spins you may need to do to get the tension correct. It may be best to find a replacement and make sure it's locked in place.

It's a rookie move that I have done before. Same thing with doing any steering rack or column work-you gotta lock the wheel/spring down because if you spin the column or spring while they are disconnected= SRS light after the repair.

If you turned the key on with the air bag disconnected, you probably set a code.

Here's the procedure to pull codes and reset the light.

https://www.volvoclub.org.uk/faq/ElectricalSRS.html#SRSOnboardDiagnosticCodes1992Up

SRS does a self test each key cycle and light would clear itself. My SRS light on my 1990 240 clears itself out, but sometimes come back.

It's true that the SRS system does a self test each time the key is cycled, but in my experience the SRS light won't go out if there's a stored code. Disconnecting the battery won't clear the code either. It has to be done through the diagnostic connector.

ZVOLV said:

Pull the bulb for the inspection and then fix it?

You probably didn't lock down the clockspring when you pulled it and it unravelled. It's tough to spin em back to the proper tension. I couldn't tell you how many spins you may need to do to get the tension correct. It may be best to find a replacement and make sure it's locked in place.

It's a rookie move that I have done before. Same thing with doing any steering rack or column work-you gotta lock the wheel/spring down because if you spin the column or spring while they are disconnected= SRS light after the repair.

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No I didn't lock it down, just pulled the airbag free of the wheel and disconnected it. You are right, rookie mistake!

This is mildly off topic but I'd still like to know if you'd be able to pass with simply pulling the bulb on the SRS light? How thorough are things over the pond?

Removing the airbag won't damage the clock spring.

you have to put it in the microwave for 45 seconds for the rubber to soften up before installing it

hiperfauto said:

Removing the airbag won't damage the clock spring.

Click to expand...

I must have read incorrectly. Removing the WHEEL without locking the spring down can damage it.

I would double check your work and make sure the connector is fully seated.

Pu the codes.