Rotary coupler airbag circuit continuity question!

OK, so my last question - is there any way I can test this rotary coupler without having to fit it and hand my car over to the garage for £66?

Yes,look carefully at the ends of the plugs.Work out how to push back the shorting bars,then check with your meter.£66 is plenty for a reset.

fishsponge said:

bugger... this means I basically have to fit it and then pay my garage to try and reset the light (they charge £66 and no other garage near me is able to do it).

How can I test this coupler while it is off the vehicle?

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Try to get two proper male plugs from the scrapyard and connect them to the rotary coupler then use the ohmeter like before...they're supposed to undo the shorting bars

what do shorting bars look like? which plug are they in?

as for £66, that is the garage's minimum charge basically, and no other garage near me (even the local indy Land Rover garages) is unable to reset these lights - their computers don't think my car has an airbag, so cannot reset the codes!

This 66-quid-per-shot garage is the only one who has a computer that can talk to my airbag unit!

Its been a while since I did srs on a D1,from memory they didnt use the 16pin plug,but used a separate 4 or 5 pin plug hanging around with the wiring under the dash.

well, my rotary coupler has a 7 pin (I think it's 7...) for the horn and cruise control, and a separate 2 pin for the airbag.

Hi
There is a special way in which you have to remove a rotary coupler or you'll knacker it. It is detailed in Rave.

I've had to fit a new one to my RRC which is the same as your Disco 1, I had to do this because I took my steering wheel off without having a look at the Rave procedue and broke it .

In the end once I found out how to remove one properly and I got one from a Disco 2, removed it myself so knew it was ok.

Have a look through Rave for removing the steering wheel and it will show you how to do it.

Your diagnostic plug for your SRS is a seperate plug just under the dash

Cheers

Graeme

What Rave says about removing the rotary coupler (apart from how to remove the plastic cowlings etc...) is:

1. Disconnect battery (did not bother).
2. Remove steering wheel.
3. Disconnect rotary coupler multiplug from steering column harness.
4. Place adhesive tape around moulding in position A to prevent rotation (I thought the locking pin served this purpose...)
5. Release clips securing rotary coupler to column stalk assembly.
6. Remove rotary coupler from column stalk assembly.

DO NOT rotate mechanism whilst removed.

This is odd because I don't see any strange instructions here or specific procedures to follow - it's just a case of unplugging it.

As for not rotating it whilst removed, this is also strange because you have to do this to center it before re-fitting it, especially if you are fitting a used one.

And other than trying to find two male plugs from a scrappy I don't know how to test this. The scrappys I know of don't sell male plugs on their own - you have to buy whole parts from them...

Hi

If you don't apply the tape it will rotate. But it should also explain how to recenter it if it has rotated.

It might have been in the D2 rave that gave more instructions, I'll need to go and have a look as it's been awhile since I've done it. I'll have a look tomorrow as it's all out in the garage and I'll also have a look at my spare rotary coupler just to remind myself exactly what it's like.

I knackered mine because I never fitted the tape when I removed the steering wheel and when I refitted it and turned the steering it stretched all the wires as it was not centered.

Pitcaig said:

Hi

If you don't apply the tape it will rotate. But it should also explain how to recenter it if it has rotated.

It might have been in the D2 rave that gave more instructions, I'll need to go and have a look as it's been awhile since I've done it. I'll have a look tomorrow as it's all out in the garage and I'll also have a look at my spare rotary coupler just to remind myself exactly what it's like.

I knackered mine because I never fitted the tape when I removed the steering wheel and when I refitted it and turned the steering it stretched all the wires as it was not centered.

Click to expand...

that's odd because every rotary coupler i've had will not rotate while out of the wheel unless you push in the locking pin...

It does explain how to re-center it - you have to push in the locking pin and go all the way anti-clockwise and then 2.5 turns to the right and then let the locking pin out again so it will not rotate further.

How it rotates without the locking pin being pushed in i'm not sure...

I'll have a look at the one in my garage tomorrow and try measuring the continuity in the wires like you've done with yours and let you know how I get on.

fantastic - thank you so much for this! i wouldn't be bothering with this if the MOT rules hadn't changed!

i'm on my third coupler now, and knowing if this is broken or not before ordering my fourth one would be great... I look forward to your results!!

Hi

I've just been out and checked my spare one. There is continuity between the Red and Yellow wire. Inside the plug which connects to the Airbag is a small coil which links the two wires together.

So I would check all the other wires for the horn and crusie control and if they check out ok the I would think the coupler is ok.

Hope this helps

Cheers
Graeme

hmm... so basically both pins are electrically connected both other pins, right?

I know the horn and cruise control wires are fine. A different garage has said that this should not be the case and my coupler is knackered... tough choice now!

Hi
Yes they are connected through a small coil which I suspect is there to filter out any high frequency noise to prevent an unwanted discharge.

I took the plug apart to check it and it is as it should be. The rotary coupler I have is from a 1994 RRC so I would assume it is the exact same as yours.

Cheers

OK... well I think i'll give it to the garage and ask them to fit it and reset the light.

if it does not reset the light, I guess i'll need a new airbag... very unlikely though (I hope).

Right - new plan!!

Either me or my local garage (with no diagnostics computer) is going to fit this one for me again and I will then try to get a cheap garage to reset the light.

If they cannot reset the light, I will take it to the more expensive garage to get them to reset the light.

If they cannot reset the light either, then I will get the more expensive garage to buy me a brand new coupler and fit it. If that does not reset the light then I guess i'll need a new airbag...

There's more reason to this plan than I have put here, hence why it may sound like an odd plan.

For the money u'll spend if u go untill the end of your plan u could buy your own hawkeye

Hi

What is actually wrong with your SRS system?

Are you sure it's the rotary coupler?

You would be best to get the codes read as there is many faults which bring the SRS light on. Because you could be spending alot of money on the rotary coupler only to find out it is some thing else that is at fault.

The diagnostic plug should be under the trim you drop down to access the fuse box and it's on the left hand side of the steering column. If I remember correctly the plug is red.

Cheers

I know it's the coupler because I crunched the old one which made the light come on.

I replaced it with another from a scrappy and that didn't fix it. Garage then investigated and traced the fault to the coupler.

Also, does Hawkeye do SRS light on a Disco 1?? I thought it only did Disco II...