airbag problem
Discussion
I'm new to posting on forums, but I'm hoping I can get some help or advice. For the past few days the SRS warning light on my dashboard (1999 Mini) has been lit up permanently, I took it to my local garage and they contacted someone they use that deals with airbag repairs. After having a quick look and twist of the steering wheel he told me it was something to do with what he described as a 'plastic ring' in the steering wheel area, (sorry I don't know any of the technical terms), and quoted me £200 for parts and fixing. Today I've had a look around some other forums and similar problems suggest it might be something to do with the SRS computer and advise using computer diagnostic equipment to find out what the problem is. Another garage has quoted me £47 just to look for the problem with this equipment, so now I'm not sure if I should go with the £200 quote for the plastic ring, or if the computer diagnostic equipment would find a completely different problem. I don't mind paying for what it needs, but don't want to be wasting money on the 'plastic ring' if it's a computer problem and vice versa. Any advice would be very welcome.
For the air bag to work properly all the electrical connections to the sensors etc must be perfect, even condensation in the wrong place may cause the SRS warning light to stay on. When my SRS light began staying on, I just disconnected and reconnected all the electrical contacts and all was back to normal. There is a connector in the steering wheel hub, attached to the rotary slip ring, and others which plug into the air bag control box (situated under the rear seat) plus one on each seat belt tensioner (you have to remove the rear "side bin" liners to get at these) In my case it is always the connector in the steering wheel hub that is at fault. This is the first thing to try, but you must first "deactivate" the air bag by disconnecting the positive and negative leads from the battery and waiting at least 1 hour. Then remove the air bag from the middle of the steering wheel by unscrewing the two retaining bolts (found on the underside of the wheel) Lift the airbag clear (be gentle with it) and disconnect the wiring connector from the centre of the airbag unit. This may be the faulty connection but since the air bag is out it is worth checking the one attached to the rotary coupling. This entails removing the upper and lower steering column shroud. Once removed, the connector for the horn and the air bag will be visible. Just unplug them and reconnect, but be careful not to disturb the position of the rotary coupling (or mark it so it can be returned to the correct position before refitting the steering wheel)
Reassemble everything, then once the battery is reconnected, turn on the ignition whist standing outside the car (arm through window). Hopefully the light will come on then extinguish. If it stays on, deactivate the airbag again then disconnect and reconnect the other connectors mentioned above (under the rear seat and in the side bins). If this dosen't work then a new rotary coupling may be required.
Removal of the steering wheel etc is explained, with pictures, in the Haynes Manual for 1969 to 2001 cars.
ETA: Forgot to say that the steering wheel has to be removed after removing the airbag and before removing the steering column shroud.
Reassemble everything, then once the battery is reconnected, turn on the ignition whist standing outside the car (arm through window). Hopefully the light will come on then extinguish. If it stays on, deactivate the airbag again then disconnect and reconnect the other connectors mentioned above (under the rear seat and in the side bins). If this dosen't work then a new rotary coupling may be required.
Removal of the steering wheel etc is explained, with pictures, in the Haynes Manual for 1969 to 2001 cars.
ETA: Forgot to say that the steering wheel has to be removed after removing the airbag and before removing the steering column shroud.
Edited by GTRMikie on Friday 1st August 09:37
One thing which plagues all cars equiped with airbags is dirty/intermittent connections. As previously mentioned by disconnecting and reconnecting the various sensors you can normally make the faults "go away" for a while. Don't worry though, in virtually all cases (except if the airbag itself is faulty) the Airbag system will still respond in the event it is needed !!
The main problem is that each component in the system has a resistance built, in so the Airbag ECU can tell if the component is connected correctly or not. If the connection becomes dirty or intermittent (or reversed in some cases) then the resistance is "wrong" and the ECU throws the fault light. Most more modern cars suffer with something called the "occupancy sensor", which tells the ECU if there is someone sitting in the seat or not !! As you are most likely to adjust the seat for different drivers, and all the dirt and rubish which gets thrown on the floor of the car collects under the seat you can see why these are the usual culprets !!
In the case of the mini I don't think there are occupancy sensors in the seat (not sure), but as already described there are sensors around the seat belts and stearing wheel. In fact if you look at the "aftermarket" stearing wheel kits for mini's the company supplies a resistor to connect in the circuit to keep the Airbag ECU from throwing the fault light all the time........
So I think the advice given is good, and the precaucions are sensible. From memory the Airbag ECU is mounted on the underside of the rear seat bench, the wiring runs under the carpet on the passenger side of the car, and I guess the stearing slip ring will most likely be the culpret, although if there are switches in the seat belt buckles these are also pretty likely to be either dirty or disturbed in normal use.
Good luck !!
Phil.
The main problem is that each component in the system has a resistance built, in so the Airbag ECU can tell if the component is connected correctly or not. If the connection becomes dirty or intermittent (or reversed in some cases) then the resistance is "wrong" and the ECU throws the fault light. Most more modern cars suffer with something called the "occupancy sensor", which tells the ECU if there is someone sitting in the seat or not !! As you are most likely to adjust the seat for different drivers, and all the dirt and rubish which gets thrown on the floor of the car collects under the seat you can see why these are the usual culprets !!
In the case of the mini I don't think there are occupancy sensors in the seat (not sure), but as already described there are sensors around the seat belts and stearing wheel. In fact if you look at the "aftermarket" stearing wheel kits for mini's the company supplies a resistor to connect in the circuit to keep the Airbag ECU from throwing the fault light all the time........
So I think the advice given is good, and the precaucions are sensible. From memory the Airbag ECU is mounted on the underside of the rear seat bench, the wiring runs under the carpet on the passenger side of the car, and I guess the stearing slip ring will most likely be the culpret, although if there are switches in the seat belt buckles these are also pretty likely to be either dirty or disturbed in normal use.
Good luck !!
Phil.
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