Trailer electronics problem, can anyone help please?

mirage

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We haven't used our IW trailer for a few weeks, so hitched up yesterday to check everything was fine before venturing out on Sunday. We've found a problem, in which the indicators and brake lights won't work when the side lights are on. They are fine without the side lights. My dad and I are working on it and can't fathom out where the problem might be.
I f anyone has any suggestions, I'd be very grateful. thanks.
 

Carlosmum

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. We've found a problem, in which the indicators and brake lights won't work when the side lights are on. They are fine without the side lights..

Mine has started to do this. If the side lights are on evreything flashes if i try to indicate. Hubby has taken the plug apart & the back light bulbs out. It hasn't resolved the problem so he thinks it might be a problem with a cable junction box under the trailer. As yet we haven't looked.
 

mirage

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Thank you, we've tried WD40,ill try the sandpaper next. It is an older car and we aren't using an adapter. I've plugged the light board from my hay trailer in and that works perfectly, so we know it isn't the car.
We've run a new earth wire, and have indicators and sidelights with that,but still no brake lights, so I've just been out and bought a new trailer socket and will try that later. It is so frustrating! Thank you for all the suggestions, we'll keep trying and if we can sort it, I'll report back in case it helps someone else out in future.
 

popsdosh

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Do you have access to a multi meter as they are best for tracking faults. Were the brake lights working last time you used it. Are they 5/21w dual filament bulbs . Take bulbs out and clean the contact points and make sure they are put back the right way round .
 

SuperH

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Mine did this on and off last summer. We resolved it with a new socket on the truck and a new plug on the trailer. It was odd though as we put my father in laws towing vehicle on my trailer and there was no problem. We put our stock trailer on our towing vehicle and there was no problem. It was just my trailer and towing vehicle combination that it didn't seem to like.
 

Goldenstar

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I think it's the new EU standard wiring on the IW I had the issue when I got my new trailer I am sorry but I can't remember it all exactly but I have an adaptor on the trailer socket for using the older car .
It worked fine on the new defender .
 

PeterNatt

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In many cases it is caused by dampness or even water building up in the rear light units. Remove the plastic lens off each of both of the rear light units and one by one remove the bulbs and blast the sockets with compressed air (you can buy small canisters from stationary shops for cleaning computer key boards) and replace the bulb. At the same time check there is no rust in the sockets.
Another way to trace the fault (if it is on the trailer) is to get a working and charged car battery and connect the negative pole to the chassis of the trailer (you can use jump leads. Then one by one connect the positive to each of the terminals in the trailers socket and see which lights come on. If several come on at the same time (ones that are not meant to come on together) then you have identified the wire which is causing the problem (i.e insulation broken down or not connected correctly).
 

Mike007

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It is almost certainly a faulty earth wire . The lights work in this scenario by cross feeding through the indicator and stop light bulbs ,back to the car . If you energize these circuits the lights can no longer back feed as all the wires are now at 12 volts so the lights go out and nothing works. First step is to clean the plug and socket , then if this fails ,open the plug and check the wires.
 

Dry Rot

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There's some stuff called 'electronic contact cleaner' that the professionals use. WD40 is an excellent dampness inhibitor but it doesn't dissolve the layer of oxide that builds up on contacts. Just a thought.

Another thing to try is gently inserting a knife blade in between the slits in the pin in the connector. Just splay them out a fraction to they make a firmer contact with the female side.
 

Peggs

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Another thing to try is gently inserting a knife blade in between the slits in the pin in the connector. Just splay them out a fraction to they make a firmer contact with the female side.

Ahhhh beat me to it!!!

I had electric issues on my trailer and did this and it sorted my electrical issues. It's a simple thing to try before you start getting into taking things apart.
 

case895

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When you park the trailer, make sure the connector is left dangling downwards. Do not use the metal cup on the drawbar to store it as that collects water.
 

silv

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There's some stuff called 'electronic contact cleaner' that the professionals use. WD40 is an excellent dampness inhibitor but it doesn't dissolve the layer of oxide that builds up on contacts. Just a thought.

Another thing to try is gently inserting a knife blade in between the slits in the pin in the connector. Just splay them out a fraction to they make a firmer contact with the female side.

This with bells on!!!! I keep contact cleaner and a penknife in my tow vehicle for this very reason.
 

Clannad48

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This with bells on!!!! I keep contact cleaner and a penknife in my tow vehicle for this very reason.

Sorry to 'hijack' the thread but will contact cleaner get rid of a heavy coat of grease that the previous owner of my car has put on the connectors. If not, any suggestions please
 

Dry Rot

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Sorry to 'hijack' the thread but will contact cleaner get rid of a heavy coat of grease that the previous owner of my car has put on the connectors. If not, any suggestions please

No.

Scrape as much excess grease off with an old knife, then try washing with a solvent like diesel, white spirit, paraffin, or petrol (be careful!) with an old paint brush.
 

popsdosh

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Sorry to 'hijack' the thread but will contact cleaner get rid of a heavy coat of grease that the previous owner of my car has put on the connectors. If not, any suggestions please

Yes it will it is solvent based so will do the trick . It is actually dangerous to use WD 40 or any other oil based product as I have seen a few plugs that have burnt out through this. We use a lot of the contact cleaner on the farm as the machinery nowadays rely so heavily on electronics and the warranty on them is invalidated if you use WD40
 
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