Rotary Coupling advice

Si Click said:

I have an SRS light on a 1999 D2 TD5 ES. The fault code is B1008 "Open circuit in Drivers Airbag - Permanent". The OBDII decode would be "Too high resistance in Drivers Airbag", which sounds like the same thing.

I have put a 2 ohm resistor in place of the airbag, reconnected the battery and tried to clear the fault with no success. I have also tried this unsuccessfully with another airbag, so I'm reasonably certain that the airbag itself is not the issue. That leaves the Rotary Coupling as the most likely culprit.

I have read every thread I can find on this subject - and there are a few. One of them once had pictures on testing and replacement which would have been ideal, but they are no longer available, so I'm left with some questions.

If I understand right I should be able to remove the wheel, and whilst leaving the coupling in place, disconnect it from the main loom and because of shorting bars I should be able to test continuity of the airbag circuit just by testing the pins in the airbag connector. Is this right?

Assuming I detect an open circuit (hope I do 'cos I have no idea where to look otherwise), I need to replace the coupling. The correct one seems to be YRC100350. Is this right?

At £200 a new one seems steep for what is in essence an extension lead, but given they need treating carefully is a used £20 one likely to be serviceable? There is at least one for sale that seems to come from a breaker that understands their fragility and has been tested, so £45 may be a decent compromise. I would ask the seller if the halves were secured with tape before removal, but there is nothing to stop them saying yes and sticking some tape on before posting. I may be better off keeping quiet and getting a confidence check if it comes with tape.

Finally can anyone point me to a definitive guide to removing without breaking (I might need to put it back) and replacing without cocking it up? I have not worked out how to download or access RAVE, but I do have a Haynes manual which makes it sound simple. Is the trick just to mark the position of the wheel before removing and to prevent counter rotation of the coupling with tape, or am I missing something?

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sierrafery said:

a common problem can be at C0257(see RAVE - Electrical library - Connector views), make sure it's well connected and if it is insert the resistor there and if you can clear the fault then you know it's the coupler, if not go to the SRS ECU C0256 and measure resistance across pins 1 - 2

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Si Click said:

OK, thanks for the advice. The replacement rotary coupler was installed and the SRS light obligingly went out and has stayed out.
The only downside was my discovery of this on the carpet after I had put everything back together. I was not expecting it, cannot find a reference to it in the parts manual and did not see where it came from. I pulled it all apart again and tried to find where it might fit, but could not do so. The outer diameter of the sleeve neatly fits inside the rotary coupler, but the internal diameter is then too small to allow the steering shaft through. The D2 is driving fine without it, so what is it, where does it go and do I need to fit it? Cheers.

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brian47 said:

I can't say for certain, but it could be something to do with the auto-cancelling mechanism for the direction indicator switch stalk.

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Si Click said:

I thought that too and checked the auto-cancel when I road tested it. Works fine, as does the horn, the audio controls and the cruise control.

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Lazydave said:

I believe it goes between steering column top and bottom cowls around ignition switch?

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