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How To Connect Your Trailer Socket Wires To Your Vehicle

If you want to connect your own trailer plug to your vehicle , then I hope in this article I can show you how to do so, of course you must have a tow bar already fitted to your vehicle.

First of all, let's do a proper trailer socket wiring connection. It is always best to do the job right the first time. You will see the photo below that someone has already connect a trailer socket wires to the rear right hand side taillight of this vehicle. The red arrow point to the wire which

come from the trailer female socket. This is the trailer  socket/female which you fit to the vehicle. The other side/male is connected to the wires of the trailer.


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The blue arrows point to the bad connections this person has done. You can see that the wire's ends was rip off, and then it was just connected to the terminals of the original power (positive) terminals of the lights fittings. It is sort of just pushed over the male power terminal of the lights, and then the female terminal of the power wire was pushed over the light's terminal. Not a very good connection, you will find with this kind of connection that the trailer's lights might not work


In the next Photo, you will see I have removed the wires from the light's terminals, and I have peel of a short peace to make a proper connection. See the red arrow. I am using a soldering iron to do the connections to each light's connections.


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You need. First of all, to determine which wire must be connected to which light. To find out which wire is the stop light, ask someone to help. Let the person who helps you put his feet on the brake pedal of the vehicle so that the brake/stop lights switch on. With any 12v tester (See

photo at the bottom) you can determine which wire from the trailer must be connected to the stop light wire. This wire must then be connected to the trailer's stop lights.(Trailer Tester wire diagram  to see a 7 pin trailer plug/socket wiring details)

This operation must be done to each wire you need for your trailer. For the righthand side indicator light of your trailer ,you determine which wire is the power wire of the vehicles right hand side indicator then you make the connection to the trailer female socket wire on the vehicle. You must make a note to which terminal you have connected the wire so that

you do the same connection on the male plug of the trailer. Those terminals are usually numbered 1 - 7 all depends in which country you are. The principle stays the same. The stop lights of the vehicle's wire must be connected through the trailer socket/plug to the trailers's stoplights. This is done to each light. (See Previous page)

The photo below show how the connections should look like after it is done. After connecting the wires with a soldering iron, I have insolated the connections with heat shrink sleeve, it looks clean and isolated


Proper wire connection

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Don’t forget the earth wire can be connected straight to the body of the vehicle or to the earth wire of the tail light lamp. See the Photo below.


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The next photo show how to test the trailer socket wiring on the vehicle to see if all connections are done correctly. I have used an empty plastic tool box, fit in it a 12-volt power supply with four switches. One switch for stop lights, one for left indicator light and one for right indicator, one for park lights. The wiring of this test box is connected the same as the vehicles connections. With the trailer, male plug from this test box plug into the vehicle's female trailer socket I can now test each light in dependable . You can see on the photo of the car the left hand indicator

light is on.

Testing Trailer Wire Socket.png

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You can do the same with the trailer , The trailer's male  plug is plugged into the test box's female trailer socket, then you can test the trailer or caravans lights independently . What's nice about this tester is, when there is a problem, you can keep the power on from the tester while you are checking all the  wiring/lights for open or short circuit, without the need to plug it into any vehicle to get power, or you can do it at any place wherever the trailer is parked. you can even test and repair the vehicles lights the same way. Click here for more advance tester.

Visit Our Auto Parts Store How to connect your trailer/car wires

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