What do you know about SB pre-tensioners & joining wires.

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NewcastleFalcon
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What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

Thought the forum might assist here...from one of my fleet...not French but a common "problem" sufffered also by a French member of the fleet.
own copyright N.Falcon Flooring by Livyn Balance-Canyon Oak Beige!!!
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This is what I know. Especially on 2-door cars, where the front seats are regularly moved backwards and forwards, the wiring and or connectors associated with the pre-tensioners routed under and around the seats, are subject to physical damage which manifests itself with the Airbag light being on. As can be seen from the photo this physical damage was a complete severing of the wire.

Now I reckon "Main dealers" love an Airbag Light on job...licence to print money. First of all a diagnostic fee for the all of 20 seconds it takes to do one. Then the chance to fit some eyewateringly and unnecessarily expensive parts.

Can't get the wiring seperately on this model, so for the wiring and the pre-tensioner for one of the most popular small cars in the UK lets say over £200 plus VAT for the necessary bit.

Thankfully, loads available second-hand, pulled out of scrap cars at £15-£30 quidish so thats what I'll be doing most likely, but....

Would repairing the wire be a decent alternative option?

Looks like a two-core thin walled cable something like this

Can't find the exact spec for the cable, as fitted in the car to the pre-tensioner so not sure what current rating would be appropriate. Its pretty thin stuff really and the circuit is protected by a 5A fuse.

For potential joining of the conductors I was thinking along the lines of twisting and soldering the wires and surrounding the joint in heat-shrink. Are there better/neater ways of joining thin wires?

Regards Neil
Last edited by NewcastleFalcon on 14 Jan 2017, 22:30, edited 1 time in total.

mickeymoon

Re: What do you know about SB pre-tensioners & joining wires.

Post by mickeymoon »

NewcastleFalcon wrote: For potential joining of the conductors I was thinking along the lines of twisting and soldering the wires and surrounding the joint in heat-shrink.
I did exactly that on my Berlingo 3 years ago, and it was, and still is fine..

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Re: What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

mickeymoon wrote:
NewcastleFalcon wrote: For potential joining of the conductors I was thinking along the lines of twisting and soldering the wires and surrounding the joint in heat-shrink.
I did exactly that on my Berlingo 3 years ago, and it was, and still is fine..
Thanks Mickey. Just imagine if a main dealer offered that perfectly acceptable solution....

Parts wire/solder/heat shrink........50p all in!

Never going to happen is it?

Regards Neil

mickeymoon

Re: What do you know about SB pre-tensioners & joining wires.

Post by mickeymoon »

It sure isn't. I think the design on many of them is made to fail so they can take money from you. A wire on mine had snapped right where it came out of the connector. Not even sure why they need connectors, it's not as though people remove the seats often these days is it? A single plug under a flap in the centre console would do with enough flexible cable to allow full seat movement. Many of them seem to have the plug attached to the seat base, where the wire is weak, it gets moved back and forth, and is susceptible to feet/bags, and being broken, as happened to mine.

I snipped the plugs off, twisted, soldered and wrapped the wires.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by elma »

If you see how the cars go together and the machines that fit seats the odd placement of connectors makes sense. The manufacturers aren't really thinking about the end user, they're interested in shaving 5 seconds of the cars production time.

I don't see any harm in using a similar wire, I'd choose a multicore rather than the single core in the link so it can flex more easily. The circuit is simply on or off rather than measuring a resistance so nothing should go awry.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by CitroJim »

mickeymoon wrote:
NewcastleFalcon wrote: For potential joining of the conductors I was thinking along the lines of twisting and soldering the wires and surrounding the joint in heat-shrink.
I did exactly that on my Berlingo 3 years ago, and it was, and still is fine..
I've done this many times and as Mickey says, it works perfectly well...

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Re: What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

Thanks James/Jim/Mickey that's reassuring. Fix the bit that's broken :) .

Now if I wanted to get a bit of twin core thin walled cable of an appropriate current carrying rating off the high street where would I go? Maplins do have 3A cable which looks pretty similar, but is this too "low" for the job?

Regards Neil

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Re: What do you know about SB pre-tensioners & joining wires.

Post by CitroJim »

That 3A cable will be absolutely fine Neil, the main thing is it needs to be nice and flexible. The current flows are negligible... The only time any appreciable current flows is if the thing is triggered and even then it's not much - certainly well within the capability of the Maplins stuff..

The most important attribute is that it's flexible and can stand up to much seat movement...

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Re: What do you know about SB pre-tensioners & joining wires.

Post by elma »

This looks good from Maplin.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

elma wrote:This looks good from Maplin.
Thanks James, the new section of cable will stand out nicely using that!

Seeing as 99.9% of the time, the pretensioner "fault" throwing the airbag light on will be a wiring problem bits of this thread may help others to avoid an unnecessarily high bill for sorting similar problems out.

Seems, like the airbag light does need "erasing" via an approriate scanning tool, after the repair is complete, but definitely not worth paying main dealer prices to get it done. Luckily I have a a good independant family run garage where I get my "fleet" of various makes and models tested, maintained and repaired, which will do this for me.

Thanks to all for the help. It is reassuring to get advice from trusted people who you know, "know their stuff".

Regards Neil

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Re: What do you know about SB pre-tensioners & joining wires.

Post by elma »

They had white and black I think if you'd like me to find a link?
I prefer the Orange though, it's a safety circuit after all.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by elma »

1mm cable is probably overkill as well but is less likely to break on you again.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

I like the orange too!

The twist/solder and heat shrink method for making joint in two thin conductors is has proved good for this job.

I did come across this sort of thing in searching around...simpler than soldering?

http://uk.rs-online.com/web/p/crimp-but ... s/0433078/

I suppose you could even use male/female spade connectors to effect a join.

Regrds Neil

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Re: What do you know about SB pre-tensioners & joining wires.

Post by elma »

Personally I'm not a fan of those type of connections, a soldered joint would be my choice. Crimps are perfectly good in a static environment and have there uses, especially in panels and machines, but are not what I would choose over soldering here.

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Re: What do you know about SB pre-tensioners & joining wires.

Post by NewcastleFalcon »

Thanks James I do have one of those "third hand" things with various crocodile clips and a magnifying glass which believe me I will need for any sort of close up work! I certainly don't do soldering often enough to be any good at it, but am quite confident to give this little task a go :)

regards Neil