Airbag light on/clicking from steering!

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Time_Bandit
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Airbag light on/clicking from steering!

Postby Time_Bandit » Fri Mar 05, 2010 11:28 am

Hi fellow owners/sufferers.

My vehicle:

Renault Megane Expression
1.6 16V petrol engine
05 plate
48000 (roughly) mileage
Manual

Well I have yet ANOTHER fault with my car.

The Airbag light is intermittently coming on. As is a very annoying and quite loud clicking/grinding noise coming from within the steering cowling area (strangely also intermittent).

Having done a small amount of research it would appear likely to be the "Rotary Switch".

My questions then i suppose:

1. Do Renault replace these under warranty regardless?
2. The noise actually occurred well within the warranty period (although it is now out of warranty) and so I am assuming/demanding that they cover it anyway. I do have proof that I complained of the noise. Opinions?
3. Anyone heard of the handbrake warning light being delayed in illuminating after pulling handbrake on?
4. Any other 'regular' or known faults that are coming my way (I have been stung by the dephaser thing already!!!)?

Regards T_B

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Re: Airbag light on/clicking from steering!

Postby chevin » Fri Mar 05, 2010 12:10 pm

TB,

seems yes to the Roatry Switch. Air bag light is clearly the wires under the seat - search the forum on this

- other inherents - you missed the window regulators at £ 300 a fix at main stealers

Time_Bandit
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Re: Airbag light on/clicking from steering!

Postby Time_Bandit » Fri Mar 05, 2010 12:27 pm

Thanks for the reply.

Actually I thought the Rotary Switch was something that cuased the airbag light to come on (clearly I don't know what the rotary switch does!). I thought the two were linked?

I believe I read that whatever it is that is actually clicking/grinding wears out the wires or something behind the steering wheel.

I think the window regulator has actually been done under warranty (fortunately! {£300..... :shock: })

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Re: Airbag light on/clicking from steering!

Postby Anthony » Fri Mar 05, 2010 3:16 pm

The two are realated, as the rotary switch is the contact for the airbag to work. No rotary switch, no airbag.
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Re: Airbag light on/clicking from steering!

Postby milleme » Fri Mar 05, 2010 8:10 pm

Hi TB
sounds very much like your rotary switch/clockspring(same thing different names) is on the way out.My Megane did same thing last year-service light came on as well.The rotary switch contains a ribbon which starts to unravel until it starts to catch,hence the clicking sound,the rotary switch takes power through to the horn and airbag.
Renault very kindly charged me £150 inc vat just to supply-i fitted it myself,its a straight forward job just remember to disconnect battery and let car stand for half hour to let airbag discharge-for Renault to do it I think its about £300+
Hope this helps
Steve

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Re: Airbag light on/clicking from steering!

Postby triumph2.5man » Fri Mar 05, 2010 10:00 pm

Hi T_B, sorry to hear about your problems with the airbag light etc. When the warnings glow like a beacon it could be the connectors under the seat but when you mentioned a clicking noise from behind the steering wheel this leads me to believe that the problem lies with the clockspring (Renault calls it the "rotary connector"). Failure is not uncommon unfortunately! Have a butcher's immediately behing the steering wheel and you will see the round, black plastic housing that contains the clockspring which is in effect white tape. It winds and unwinds as you turn the steering wheel from lock to lock. If you look very carefully you will be able to see the edge of the tape. If the tape is starting to ressemble a birds nest, and looping back on itself, you have a problem - Houston!
The noise you mentioned has been described to me as a chafing noise, as if the kids have stuffed a bit of silver paper behind the wheel! I have quite a bit of experience with the clockspring and have changed several. In fact I have been intending to write a diatribe on here to assist other members. Perhaps I should get writing!
The main drawback is that you cannot just buy the tape/spring, you have to buy the whole switch housing which will cost you £150 if you have auto lights or £125 if you do not. I have successfully bought several via scrappies on ebay.
If you are a DIY bod, the job is not hard and after the first one I did I could do others in half an hour easily. Don't worry about the airbag provided you follow the correct procedure!
Do check those seat connectors first though. When the tape breaks, that's it, the warning lights come on and stay on!
I attach a photo of the switch unit. This includes a view of the broken tape. It breaks at one end and I speak from experience when I say it is absolutely impossible to mend! The clockspring housing can be clearly seen here.
Mike
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Re: Airbag light on/clicking from steering!

Postby davelowe » Fri Mar 05, 2010 11:33 pm

This is very interesting. I must admit I'm a little puzzled. Please correct the bits that I am wrong in the following guesswork:

1. The white ribbon is supposed to be fitted in between the circular part in the photo and the housing.
2. The ribbon connector fits directly under where the Renault logo is shown (5 or 6 pins)
3. I assume it detects the position of the steering wheel.
4. How does it work? Is there a sensor, if so where?
5. What has the position of the steering wheel got to do with the airbags (ignore this if it's a wiring loom / common connection point)
6. When you say the 'tape breaks' does it actually snap - is it looped back into the connector?

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Re: Airbag light on/clicking from steering!

Postby Time_Bandit » Sat Mar 06, 2010 1:05 am

Thank you all for the replies.

Car in at dealership ALL day.

My airbag warning light has been "diagnosed" as a wiring problem under the seat. Cost is £75!

The noise coming from my steering......they could not hear. That is both the technician AND the service advisor have not been able to hear it. So there we have it....car all sorted....right???

WRONG!!

I get in the car and guess what I can hear.......straight away.....the clicking noise from my steering (although to be fair it was a LOT more quiet than it sometimes is.....but STILL audible). I ask the same service advisor to come out and have a listen "Oh that's the rotary switch" (I kid you not.....).

I am yet to be convinced that the problems AREN'T connected!

T_B

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Re: Airbag light on/clicking from steering!

Postby Anthony » Sat Mar 06, 2010 8:08 am

The position of the steering wheel is more likely to be related to the ESP I would have thought, as drivers' airbags are round (bar some citroens) so they can go off in any steering position.
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Re: Airbag light on/clicking from steering!

Postby triumph2.5man » Sat Mar 06, 2010 8:58 pm

Hi folks. Dave, in view of your thirst for knowledge, this diatribe is aimed at you (and anybody else who may be interested!)
There are no sensors in the steering wheel. Airbag deployment is controlled by the "airbag control module" which is secured on the bulkhead. This stores up electricity and when the module detects a rapid deceleration (as in a crash), a burst of electricity fires the airbag and the seat belt tensioners. As the module is fixed and the steering wheel is moving, how does the juice get to the airbag? This is where the clockspring comes in. It is fixed to the light switch unit at one end and to the steering wheel at the other. As the steering wheel is turned from lock to lock, the clockspring winds and unwinds. Thus there is a permanent connection which allows for movement, until something goes wrong.....For some reason, the spring starts to snag and breakage follows. You will be a lucky Megane owner if your clockspring lasts the life of the car! As I said before, it is not a spring as such but a ribbon tape. This one has 7 tracks but only uses 5. You will find a similar item in your laptop, the only difference being that in a PC the ribbons can be removed and refitted. The clockspring is hard-wired at both ends.
Why the problem with the Megane? The spring is very flimsy and easily snagged. Not only that but it is very short. There is only enough length to allow movement from lock to lock - just. When fitting a new unit it is essential to do so with the road wheels pointing straight ahead. The inner spool of the clockspring housing is moved by the steering column and must be set accurately. The central position is seen as a small dot through a hole in the plastic. Get this wrong and your expensive replacement will last only as far as the first corner - snap!
Have a look at photo no 1. This shows the Renault clockspring and the tracks can be seen, as can one of the hard connectors. Look at the other end and you can see the clean break which is impossible to bodge up.(You can't really mess about with airbags.) Examine the ribbon and you can see one of the places it doubled back on itself, resulting in its demise.
Have a look at the second photo which gives a good idea how a clockspring works. This one is from a Ford and is much more robust than the Renault one. Apart from that it is far, far longer than it need be and with a very smooth surface. It is unusual for a Ford clockspring to break and it will outlast the car.
The third photo shows a Renault unit dismantled. The white spool fits inside the housing (with the spring inside it) and the black cover can be seen next to it.
Manufacturers normally state that in the event of a crash and airbag deployment, all parts of the circuit must be replaced (they would, wouldn't they?) but I have used several such units with no problem. The Ford one shown I took from a write-off and it is in perfect condition.
I must add that as the Meggy has airbags coming out of its ears, it probably has several airbag control modules to handle prangs from all directions. Once a module has been fired, it must be replaced. As JLS say, "you only get one shot....!"
I have several unused airbags knocking around in the shed. What to do with them? Can't take 'em to the council dump!
They are all over 10 years old and cannot be reused (your'e supposed to replace them after 10 years but very few owners do. An old car, cost of replacing airbags? - more than the car is worth!
That's it in a nutshell. Sorry to bore you again! Any questions or photos>
Cheers, Mike

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Re: Airbag light on/clicking from steering!

Postby crackpotterpig » Sat Mar 06, 2010 11:42 pm

as an aside are you aware that the airbag itself ie the steering wheel centre is classed as a cat 1 explosive and should be stored as such.............in a lockable steel container if I recall the technical instruction when i worked at a vauxhall dealers,although i must say we did have some fun setting them off in the back yard,they fly up about 20 foot in the air lol

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Re: Airbag light on/clicking from steering!

Postby AlexB » Sun Mar 07, 2010 1:01 am

It's a very interesting reading, Mike.
There are traces of thermal damage on the insulation of the ribbon near the broken end. I mean a grove going across the tracks 1 and 2. Aren't they the horn circuit? They seem to be too thin for the rated horn current. Is it possible that the horn current causes overheating, which results in deformation and subsequent snapping? I am sure that many people upgrade horns without installing a relay...

The other strange thing is that the ribbon does not seem to be made of teflon, does it?
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Re: Airbag light on/clicking from steering!

Postby triumph2.5man » Sun Mar 07, 2010 11:06 am

Hi Alex. The ribbon had another connector on the broken end and the damage you have observed is where the plastic fitting clamped on before it was wrenched off. The horn connection is part of the switch/airbag unit but is powered independently by the conventional double slip-ring system. See attached close-up.

CPG thanks for the advice re storage etc. I will probably take these to somewhere remote in the countryside and connect to a 12v battery via a VERY long cable. Light the blue touch paper and stand well clear...One of these is a double so should make a good noise!

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Re: Airbag light on/clicking from steering!

Postby AlexB » Sun Mar 07, 2010 11:22 am

Thanks.

The procedure for disposal of airbags is described somewhere in the TNs or manuals. It involves putting the airbag into a stack of tyres and clearing the area.

Here it is:
https://ray-lee.co.uk/megane/dialogys/MR364MEGANE8.pdf
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Re: Airbag light on/clicking from steering!

Postby davelowe » Sun Mar 07, 2010 3:05 pm

Thanks Mike for an very clear explanation. Always interesting to learn something new!

I do have one question though - assuming the actual airbag unit itself needs only 2 wires to 'detonate', why not use the conventional double slip-ring technique to transmit power to it and bin the ribbon cable altogether? Even if 5 wires are needed why not have concentric rings? Surely copper rings with brush followers would be more reliable? Constantly twisting a cable is asking for problems.
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