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Please Help With Towbar Electrics.


Shedgirl

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Hi there, I'm wondering if anyone can help me before I go nuts! I have bought an old caravan, and the exterior lights worked fine on my friend's towbar. My bmw has a 13 pin electrical socket (has been tested and works fine) on the towbar and because the caravan has two 7 pin plugs, I bought an adapter. 13 pin to 2x7 pin plugs. The adapter has been tested and there is a current running from the car through the adapter. ....but when I plug it into the caravan --- nothing!. So, the caravan works and the car works and the adapter works. But when I put them all together nothing works! I'm bamboozled. And before I treck to the (pricey) motor electrics place I'm wondering if anyone can shed some light on this for m? thankyou thankyou in advance.

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Wiring systems changed around 1998 so you probably need a tow bar fitter to check it out for you. :angry:

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Have you got a test meter?

 

If so you can test the voltage from the pins on the 13 pins on the car and then plug the adapter in and check voltages again.

 

The pin uses are as shown in the following link

http://www. yoc4x4. co. uk/pdf/Ystradgynlais-Overland-Club-Ltd_Towbar-Wiring. pdf

 

 

The caravan exterior lights are through the black 12N plug and the internal lights/fridge are through the white 12S

 

For some of the test on 12S the engine has to be running.

 

Also check the brass pins on the 2 caravan plugs are clean and the contacts around the rear lights on the caravan are not corroded as sometime the lights will earth back through themselves and do funny things.

 

You can also test the continuity of the caravan from the 12N plug with the meter and see if all circuits are intact.

 

Hope this helps

 

Brian.

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I would fit a 13 pin plug to the caravan, costs about £10 to buy, i fitted both original cables into a 13 pin on my last caravan, you will need to adjust the cable entry to get them in.

 

I used silicon afterward to effect a seal.

 

If the wiring needs alterations, this can be done while fitting the new plug.

 

The caravan club has all the variations to the wiring on the web site. Its a pdf file.

 

 

3. Which System Do You Need?............................................................................................2

3. 1 Pre-October 1979 Caravans. ..........................................................................................3

3. 2 October 1979 to 31 August 1998 Caravans. ...................................................................4

3. 3 1 September 1998 And Newer Caravans. .......................................................................5

 

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The fact that you tried your caravan on a friends car and the lights worked suggest there is nothing wrong with the caravan wiring, the road lights at least. The changes in wiring in 1998 were to do with the fridge and battery charging, the road lights stayed the same.

 

One thing to ensure is that the 13 pin socket is fully rotated 90deg to make contact. However you say you have checked the voltage on the pins on the adaptor outlet with it plugged into the car. Do I understand that correctly? Have you checked every pin?

 

Brian

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The wiring needs to be checked through with a meter or if you don't have one, a 12V tester screwdriver.

 

If you don't know how to do that, its probably best to take it to an auto-electrician or get a mobile one to come to you.

 

Shouldn't take someone with experience long to pinpoint the problem.

 

 

 

 

 

 

Hi there, I'm wondering if anyone can help me before I go nuts! I have bought an old caravan, and the exterior lights worked fine on my friend's towbar. My bmw has a 13 pin electrical socket (has been tested and works fine) on the towbar and because the caravan has two 7 pin plugs, I bought an adapter. 13 pin to 2x7 pin plugs. The adapter has been tested and there is a current running from the car through the adapter. ....but when I plug it into the caravan --- nothing!. So, the caravan works and the car works and the adapter works. But when I put them all together nothing works! I'm bamboozled. And before I treck to the (pricey) motor electrics place I'm wondering if anyone can shed some light on this for m? thankyou thankyou in advance.

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Are you sure of the adaptor?

As your van works on another car and your car's been tested - my money is on the adaptor!

Every problem our customers have had and an adaptor is involved, the adaptor is at fault - even though they are very expensive, they all suffer from poor build - the earth wires are nearly always loose!

Either take the adaptor apart and check all the terminals are tight, or try another adaptor before spending lots of money on testing.

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Are you sure of the adaptor?

As your van works on another car and your car's been tested - my money is on the adaptor!

Every problem our customers have had and an adaptor is involved, the adaptor is at fault - even though they are very expensive, they all suffer from poor build - the earth wires are nearly always loose!

Either take the adaptor apart and check all the terminals are tight, or try another adaptor before spending lots of money on testing.

 

Not only that, the one I've got, but wouldn't use, has undersized wiring.

 

My advise is don't use one, not worth the trouble.

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I took apart my 12S/N to 13 pin adapter (different to yours i know) after i decided to to fit the 13pin socket to the car.

 

The wiring inside it was shocking - wires not going into terminals, terminal screws loose plus evidence of arcing. Now i know why my indicators were so dim on the caravan and the RHS side lights didn't work!

 

The point i'm trying to make (i'll get there!), is it may be worth taking that adapter apart and checking inside

2021 Swift Sienna Super 4SB

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