Help with Witter Towbar with no electrics

[patomlin76]

Hello

My Passat Estate has had a towbar fitted by a previous owner, and only today did I try it out properly, having to tow a small trailer of garden cuttings.

I am a first-time tower so to speak so managed to fathom out what goes where when connecting up at the rear of the car, however there seemed to be no electrical feed for brake lights or indicators. Luckily the width of the trailer is less than the car so these are still visible when towing.

The towbar looks like a fixed one that has needed cutting of the lower valance to fit. It is a Witter towbar with two electrical points - the lower one covered by grey plastic, the upper one is black. For this small trailer I could only get the plug to fit in the top one, so I'm guessing that was right.

There are two thick cables running from the towbar which disappear into the soul of the car somewhere.

Can anyone provide some clues as to where I should look for possibly a relay, fuse or other connection? There seems to be nothing output at all from the connections at the rear, but completely clueless for where to look.

(I'm guessing this thread What does this look like? has nothing to do with this?!)

Thanks in advance.

Paul

[martin1810]

Are you sure the car is at fault and not the trailer. With the top plug pushed in properly, the lights and indicators on the trailer should work. Was it pushed in properly. It has a little slot in the plug/socket.

[patomlin76]

Martin,

Definitely sure it's the car not the trailer - it's lights work on another vehicle and unless a Renault 7 pin is different to my own, there is no reason for this not to work.

As a last attempt tonight I cleaned all the contacts but still no luck. I do hardly any towing but it bugs me that something on the car isn't working. I need to try to trace the wiring back somehow, or at least find where there may be a fuse or something.

Cheers


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[martin1810]

You need to know if it has genuine electrics or not. A vcds scan will tell you if it has genuine stuff. That way you will know something without searching wires. Where to look for wires is not so easy. I always make the connections on the left behind the side trim but a fitter could choose either side.

[patomlin76]

Thanks Martin,


Having now seen a towbar specialist it seems that the two inline fuses I found in the fuse box are to do with the towbar, to supply both the permanent and switched supply

I had since removed the fuses and hidden the wires, so I am showing this photo to the specialist at lunchtime to see what he thinks - it looks like it may be as simple as plugging those two spades into a corresponding permanent and switched supply.

Thanks.

photo.jpg

[martin1810]

Yes that looks like the quick bodge method. That way the fitter doesn't have to wire into the fuse box.

[patomlin76]

OK, that sounds interesting, so what do I have to do from here - will they simply plug into the fuse box from the front, or do I need access from the rear?

As this was done before I owned the car I take no responsibility for how well the job was done, I'd just like working lights by the weekend!

Thanks Martin.

[martin1810]

Just plug spade terminals into empty fuse slot from front. One spade is probably for a fridge and the other is for the towing functions. Decide if you want perma-live or ignition live. I go for ignition live. Use a test light and poke a spare fuse holder until you find an ignition fed socket and plug the spade terminal in that hole. Bingo.

[patomlin76]

Thanks for your help. I now have working towbar electrics. When I opened up the rear of the fuse box there was a red and a blue wire already spliced in. After some trial and error I found the correct one for trailer functions.

At first I had no brakes nor turn signals but a closer inspection of the trailer plug showed severe rust and frayed wires. A quick rewire I had brakes and one indicator, the other indicator wire is so rusted on I can't remove it. I also get the telltale beep when indicating... A new plug will be bought tomorrow.

Thanks again!!


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[martin1810]

Plugs are cheap. It pays to keep a spare one so you can replace it every few years.