Towbar Wiring Not Terrano

[jims-terrano]

Hi guys has anyone fitted towbar electrics to a car with canbus?

Basically I've been looking at fitting a twobar to my skoda, got put off by the prices when it was new and didn't fancy spoiling a brand new car myself. So looking at it again and the elctric kits are confusing me. There's dedicated and they need coding which looking further is plugvagcom into my ecu and tell it that ithas a towbar.
However the universal with bypass relays are a hell of a lot cheaper and don't stipulate coding. I understand how these devices work and obviously don't introduce much load on the existing systems. Don't think my vehicle has bulb out warnings so that side shouldn't be a problem.

Any advice welcome.

 

[jims-terrano]

Forgot to say the unversal kits are 10 times cheaper too.

 

[zippy656]

It's a total pain.

If you car dose stuff to handling its not just the lights you need to get to work.
The car has to know there is a trailer attached and change settings.

 

[jims-terrano]

Great another consideration that nobody either knows or is willing to tell you.

Kind of suspect there's nothing electronic about the suspension but brakes? Who knows.

Long live Terranos far far easier to play with.

 

[rustic]

Hi Jim, 1st question, what do you want to tow with the car?
If a caravan or heavy trailer, then you should have a proper unit coded to the car, this helps with brake stability in case of jack knifing etc. rear guard light deactivation, disabling reversing sensors, trailer bulb failure, and even detecting the trailer being disconnected thus setting off the alarm.
Some tow bar companies fit basic kits that feed off the can bus, take a small current so "should not" interfere with the canbus. BUT if they do or are blamed to have done damage, then you are looking at repairs that would be out of warranty.

I looked at the price for after fit for our yeti, it was going to be £600-£800 had it been done as an order at the factory, it would have been cheaper, however, as ours is a Greenline, it would have increased the weight, so couldn't get the lower emission category, as would a spare wheel, or glass sun roof, so it was not offered as an option.

We only wanted a towbar for a 5'x3' Klinn camping trailer, or to fit a bike carrier and lighting board, so I had to look elsewhere.

I was aware of issues with "tampering" with wiring in the can bus, so as an electronic engineer I designed my own isolated interface, I used this to connect to an off the shelf black box for can bus interfaces, but due to isolation, there was no electrical connection other than ground between the trailer socket and the car wiring, thus protecting the can bus.
I connected all my wires by micro surgery to the innards of the rear lights, so if you fitted new lights you could remove ALL traces of electrical connections.
In brief I tapped off each bulb with a resistor that took a few mA this went through an opto isolator, which then connected to the black box.
The opto isolation provides 5000 volts isolation, so you could stick 5000 volts on any pin of the socket and the car will be safe, the black box would be wrecked though.

Costs.
I bought a new tow bar EU approved from towsure at a special once in a life time offer for £60, bought it even though the Yeti hadn't been built at the time, the black box, maybe around £30, a few opto isolators fuse holders connectors less than £20
So for around a £100 I have my towbar.
Now if I was to tow a caravan, I would probably upgrade to a fully integrated system.

Before anyone asks, I don't feel upto making any new ones, as it does require some skill to wire in too.
So why did I do it...? as an Engineer... Because I could. :thumb2
Rick and many others will understand this view point. :augie

Hope this helps.

Richard.

 

[jims-terrano]

Well it's for the Roomster Rustic so like you just a small camping trailer though in theory the car can and others have used my engine variant for towing small caravans. Doubt I would ever do that but I always like to do things that cover any eventuality. I've looked at the vehicle specific kit which is plain ridiculous price. Will have a word with a bloke that does my mot's as he is a vw specialist so may have some useful advice.

 

[rustic]

Towsure do the kits for canbus, got mine from PF Jones or someone like that, that bit is standard, and I could have tapped into the wiring loom but at the time the Yeti was a brandnew car, and we have the extended 5 year warranty, so I didn't want to risk it, there was also a lot of scaremongering on the Yeti owner's forum... don't do it, cost £1000's to put it right etc etc
My bit was the interface between the two, just in case, but I think was over done, and that a good VW tow bar fitter can give you the very basics, I would guess for £250 -£300 You can always try Towsure in Sheffield for a quote.
But all singing all dancing will be a lot more as I said in previous text.

The next thing, do you want all the 13 pin socket arrangement ? you only need a basic old fashioned 7 pin for the camping trailer.
Upgrade later if required.

On the Yeti, I had to remove the rear bumper, special plastic covers to give access to the bolts, remove half the trim in the boot etc etc...
Stripping down a brand new car when the paint was virtually still wet was quite a major task. Cutting the bumper, was even worse.
They say measure twice, cut once, more like measure 10 times mark it up in masking tape and pencil, then have two cups of tea, measure it again... and make that first cut, and still keep measuring lol.
I got it right first time though.
I am not without some experience, I have fitted tow bars to a Toyota Corolla, Ford Escort, Austin Ambassador, Vauhall Vectra, Rover 600, the Maverick, and now the Yeti, but this was the first ever canbus, so a lot of web searching, electronic calculations, and practical experiments to ensure my circuit would work before putting it in place lol.
Rustic

 

[jims-terrano]

I'm old fashioned Rustic, 7 pin 12 n and s for me. But to begin with just a 12n for the trailer.
Not in too much of a hurry though so will have a think what to do first.

 

[rustic]

Hi Jim, have a look at PJ Jones web site, Old Trafford Manchester, they have nearly half price offers on some tow bars. Yours included.

They explain the electrics etc, so worth a read when you get 5 minutes, at least it might help you understand what each bar can do, we just went for the standard 2 bolt fixing, but you can have removable ones, so it looks like you don't have a tow bar.
I prefer the fixed bar, making people give you that extra bit of space when parking near you lol.:thumb2

http://www.pfjones.co.uk

Hope it helps, there are just too many options, but when you see the prices, often the decision is made for you lol... :thumb2
Best regards,
Richard

 

[jims-terrano]

That looks a comprehensive site and have heard of those too. Will get in touch and see what they say about the little car.

Cheers