The tow bar with 2 x 7pin electrics was fitted to our Touran Tow car 14 years ago and all has been perfect ever since. We succeeded in towing the Puck home from Bristol using a simple 7 pin to 13 pin adaptor with no grey plug in use, as the Puck has 13 pin electrics.

The tow bar with 13 pin electrics was fitted to the Kuga about 4 years ago at a guess and when we hooked up the Puck for our first trip all went well. However, when we tried to get the towing lights to work for the return journey they were dead. Being NOT a fan of 13 pin electrics I checked with the site manager if I had plugged them in correctly and he said all was OK. Eventually we had to make the shortish distance homw with no rear lights on the Puck. We believe that there was plenty of rear car light showing to each side and through the Puck windows but we took our time as well.

Yesterday was the first occasion I was able to look at it and believing the Kuga was at fault, I plugged our 7 pin trailer board into the Touran and all was OK. I then plugged the board into the Kuga using a 13 pin to 7 pin adaptor and we had zilch. OK, defo the Kuga or so we thought.

Taking the Touran to meet the Puck and plugging it in but now using a full 2x 7 to 13 adaptor, the Puck lights were all over the place. Only one indicator and brake lights stuck on permanently, no side lights no flashers AND the high pitch indicator peep sound from the car would not shut off unless I disconnected the battery.

Tried the Touran on the 2 x 7 Troll and the lights were all over the place. Now that was working fine last month. Connecting the trailer board to the Touran gave me the same result.

I've overcome the high pitched sound by removing the appropriate fuse but will now have to go to the experts to figure it all out. It looks like the Puck is the culprit but I can see no reason why. While writing this I suppose I haven't yet looked at the wiring of the 2 x 7 pin to 13 pin adaptor which is a brand new purchase but no adaptors were responsible for the failure between Kuga and Puck which started the saga. Both are on 13 pin electrics.

Randa

Hey, thanks for that Dinky. I'll take a look when the weather is better.

What I have done today is checked that the 1 x 7 pin trailer board is OK. I've "hot wired" it to a nearby battery and all the lights are OK.

I'm not going to try either car until I get them checked out because I think I may have sussed out the problem.

By "hot wiring" the Puck rear light cluster to the battery and probing each flow and return, I'm getting a lot of sparking from the tail lights and indicators. I've unscewed the pesky 13 pin plug to find that there is a broken black wire which I believe to be the all important earth wire for the fridge and battery charger and this wire should be in terminal 11.

Steve (and Debbie) pointed out the following explanation we had on Facebook to a member who's Volvo was playing up on the way back through France.

Zitat

---

Regarding your towing electrics problem. I recently saved this post because Andy Dingley mentions the wiring in his comments and he talks about some shoddy common practice in the wiring. this is the post, you have to drill down to find Andy's comments. https://www.facebook.com/groups/eriba/pe...773986182771108 or this is a copy of one of them...

What was getting hot? The plug on the caravan? The socket on the car? The relay box inside the car boot? There is nothing in the car socket that should be getting hot. But they do. So this is an indication that at least one of the pins is making a poor connection. That's a high resistance, and if there's current flowing through it, then that gets it hot. First thing is to try and sort out the socket (and plug) that you have. 13 pin plugs can get a little misaligned, there's a 'green cap' you can get cheaply which can help sort them.

Then a squirt of contact cleaner in there, a brush around inside (tiny bottle brush or big dentist's TePe interdental brush.) and then a dribble of Servisol contact lube (WD-40 is not the same thing). Anyone storing electrical devices outdoors should have some Servisol. To get a connector hot needs some power going through it. Check the lights, but I doubt it's them. I would suspect the fridge, because it's the only thing pulling enough power to warm up a socket. So that's pins 9,10,11,13 to check.

Also pin 3, because that's the earth for all the lights and causes all sorts of trouble if it's wrong. Also check the connection from the cable into the back of the plug and socket. These should have bootlace ferrules crimped onto the cable ends, before being screwed into the plug terminals. Especially for the power pins. Don't just stuff twisted bare cable into a screw clamp. Don't solder the cable ends and put them into a screw clamp. Also, once assembled, these contacts should be sprayed with either a contact lube, or a contact varnish. (A bootlace ferrule crimper is a tenner from AliExpress.)

Do you know what 'trailer light faults indicator' means? Probably not (they're secretive about this stuff) but maybe P F Jones' website does. Which faults does it detect, and does it hint as to which one? Does it look for power circuit faults, or just lights? What you might have (because it's not uncommon) is a fault that's not a 'fault' and it's not even a design error (except that it is), it's just shoddy practice. A fridge should be wired onto a 13 pin caravan through 4 wires. If it only uses 2 (power from pin 10) then it can work fine, but if it's then plugged into a car that was wired correctly for 4 wire supply, it can pull an excessive current from pin 10 when it should be pulling it from pin 9 instead. This doesn't usually overheat the plug/socket, but it can overheat the cable to them (pin 9's cable is fat, pin 10's is thin) or (more commonly) it pops the fuse in the voltage-controlled relay.

You can detect this with a specialist tool that's £800 (!) in a posh garage box, or mine is made of a few cheap ammeters on a plank, spliced into a cable between a 13 pin plug and socket. Measure the current in the pin 9 & 10 circuits and also the three earth returns, and really see what's going on.
www.facebook.com

---

Another reason to me at least, to favour the 2 x 7 pin arrangement because there is a some pretty hefty wiring going on in the 13 pin plug with pin 9 (12V permanent power), 10 (12v ignition for fridge snd battery charger), 11( Earth for Terminal 10)and 13 (Earth for Terminal 9). All housed in the same size plug as a 7 pin. No wonder it needs to be screwed in.

Randa

When I was having electrical problems, I replaced the 13 pin plug and cable to the front junction box under the caravan. I found quite a few loose spade terminals and corroded wires. Since replacing the cable I've had no further problems. *nervously touches wood*

Is this of any use? How to replace cable

Thanks mate. I'll have an in depth look at that when I get stuck in.

Not looked under the van yet but there are two junction boxes like that next to the battery under one of the seats. What is interesting though is that your Pin 11 Earth, White/Black, is listed as being 2.5 mm where in my case the broken black wire is only 1.5mm and could have burned out because to me it is too thin but is part of the 13 pin plug loom. Another thing to look at.

Randa

OK. The towing electrics problem is definitely the Puck.

Thanks to a very nice man (Mark) the owner of Port Talbot Tow Bars, he easily found the fault in the Kuga. A blown fuse. So after he fixed it (no charge) we came back home and tried the Troll electrics by "hot wiring" and found that the towing electrics worked fine. Didn't chance the grey plug (fridge and battery).
Then we put the Kuga onto the Troll using a 13 pin to 7 pin adaptor and all is working OK (touch wood).

However when we took the Touran to get it checked out it would appear that the Puck has blown the relay so a longer job. We'll get it sorted later.

OK. 13 pin electric loom cable and colours.

As I mentioned above. Mr Calder's list of colours and wire thickness differs from the one I got off the internet which in turn, differs again from what I've actually got on the Puck. Upon deeper research it would appear that although most diagrams and looms stick to the "standard" colours if I can use that term, unlike the constant of the good old 7 pin plug, there are many alternatives to the colour and thickness of the 13 pin plugs.

When I mentioned this to the Tow Bar guy he showed me the wiring he uses and it is totally different again.

Anyway, next job is to poke some wires into the plug holes of the Puck 13 pin and see what's what.

Randa

Update.

It's taken some time due to this horrible weather we've been having and an unplanned trip in the Troll to look after sick relatives but I've cracked it.

After a lot of research, it would appear that nothing is straight forward with 13 pin towing electrics. Different websites show different wire colours, none of which totally match the wiring on our Puck except for the 7 colours that run the towing electrics which seem to be standard and universally agreed on. Also, dependant on where you look, some websites refer to thicker return wiring for the fridge and the battery charger. All in all, a bugger's muddle.

OK, after poking a wire in the appropriate towing electric holes in the 13 pin plug, I was getting brakes, side lights, but only one indicator and one side light, of course, on opposite sides. Checked the bulbs and they are OK so bad earths?

After a lot of head scatching and discussions with the boss we decided to go down the road of our recent adage "Keep It Simple" so I have removed the Puck 13 pin plug and wired up a 7 pin towing electrics plug with no battery charger and no 12v fridge and after curing or semi curing the bad earth situation on the two bulbs, all works Hunky Dory.

Yes, I know I'm in a huge minority who absolutely hate the idea of 13 pin electrics (the Troll is 2 x 7 pin ) and because we ALWAYS use campsites with EHU and only ever drive about 3 or 4 hours between campsites, we see no really advantages of keeping the fridge and leisure battery topped up by the car. I keep getting the arguement that the 13 pin doesn't fall out because of the twist, I dislike the twist and in all my decades of towing I've never had a 7 pin fall out.

If I could have made some sense of the 13 pin plug on the Puck, obviously a retro fit as the Puck is pre 13 pin electrics, then I would have had a go at keeping it even if only as a challenge. The plug looks to have been professionally fitted and the reason the fault didn't show up when we bought the van is because we brought it home with the Touran with 7 pin wiring, by using a straight foreward 7 pin car to 7 active pin 13 pin caravan adaptor.

To start with, 13 pin electrics normally only have 12 wires and pin 12 is not normally used. The Puck doesn't have a reversing light so there was no wire for pin 8. One of the most important wires, the earth for the 12v ignition (pin 11), which runs fridge and battery charger (Pin 10) was missing. There was a broken small black wire but on further investigation it was not a wire but a sheath for a fine fibre optic which was not in use.

So much for a 13 pin plug. It only had 10 wires in the sheath. Perhaps at a later date, I may take the Puck down to our local friendly Tow Bar Expert as I need to take the Touran down there some time to see what damage the wrongly wired Puck had done to the electrics on that. Very little I know, probably a stuck relay which will not stop beeping when the car battery is connected. (I've removed the appropriate fuse).

So, to list my additional towing aids, all bought in the past month and to join my simple 13 Pin car to 7 Pin trailer adaptor which we've had for years and will now be employed to tow the Puck with the Kuga.

1) 7 pin car to 7 active pin 13 pin caravan adaptor bought urgently especially to bring the Puck home with the Touran after purchase.(we didn't have the Kuga then).
2) 2 x 7 pin car to 13 pin caravan adaptor which was intended to tow the Puck with the Touran.
3) 13 pin car to 2x 7 pin adaptor for towing the Troll with the Kuga
4) 3M 7 Pin Towing Trailer Light Board Extension Cable Lead Socket Wire Curly Cable for using with my trailer board, if ever I need to employ it on the Puck or Troll. (This is a lovely bit of kit )


So, at least for the time being, another problem off the list.

Randa

Oh, I can see a can of worms has been opened here.

I've had several cars with twin 7 pin electrics and remember the wiggling, contact cleaning and lights sometimes not working. Then my first car in 2014 with 13 pin socket and what a joy. No more wiggles, dirty contacts or iffy lights.
Why put up with lights that do not work correctly. Why have a battery that you cannot charge or a fridge you cannot operate on the move. You've paid good money for them so get the things to work as they should.
Push the plug into the socket, a slight rotation and as Guy Martin would say, "Jobs a good-in"

Colin

Had various towing trailers over decades all working fine on 7 pin electrics and the Troll has worked fine for the past 14 years with 2 x 7 pin electrics. On older Eribas you still have to wobble light bulbs to get a good circuit whether you use 7 pin or 13 pin and as far as keeping the fridge cool while travelling, I bet the battery input to keep and already cold fridge cool is very limited.

SDA, tell me what the proper colour codes are for 13 pin electrics and I'll show you several websites that will disagree. Even our local towbar centre uses diffent coloured cable. At least 7 pin lighting wiring sticks to the accepted international colours.

No, I still stand by what I think and that is there was nothing wrong and there is still nothing wrong with 7 pin electrics and IF I was to modify the Puck I would just get a grey 12S 7 pin plug to go alongside my black one. So many things today are over designed. Simple is best.

Randa

I'm much happier now that I've taken control of the towing electrics on both vans. I sort of know what I'm doing when dealing with 7 pin electrics and I would hate to be in the situation we found ourselves in on our last trip with the Puck when we had to tow her home without rear lights. Fortunately we were only about 30 miles from home on a sunny day, with lots of motorway in between.

I would hate to be stranded further afield with no rear lights, especially on the Troll.

Randa