# trailer light wiring issues



## utilitylocator (Jan 13, 2009)

When I plug in the trailer lights to the truck, I get the following results:
a) the taillights work just fine
b)the left turnsignal doesnt work but the bulb is good
c)the right turnsignal makes the emergency flashers come on instead
d)When I brake, it completely kills the tail lights on the trailer and the brakelights dont come on. 

I rewired the trailer because the old wires were severely damaged when I got it. The wireing kit was realy simple and I matched up all the colors correctly. The trailer has the ground wire connected to the frame on the tongue. I even sanded it to make sure it was good. Im at a loss...:confused1:
The trailer is an old pickup bed frame. the trailer wires have a squareish conector. The truck has a round connector. There is an adaptor inbetween.


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## Bill7 (Dec 18, 2009)

Feel your pain. I need to go out today and mess with my trailer lights.

All I can say is double check the grounds. Also, maybe replace the connectors (vehicle and trailer). I sealed all my wires LAST time I rewired. Darn mice.

Good luck!


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## BigD9 (Mar 10, 2011)

First thing to check is the ground. Connect a wire from the trailer ground connector to a good ground on the truck. Now what does your lights do? Still giving you nutty results? How many wires are at the end of the truck connector? How many wires are on the trailer connector?

If it were me, I would start by checking the truck output. Use a 12 volt light or a 12 volt tester. Ground one lead and touch the other lead to the truck wiring pins. One pin should light up when the taillights are on, one pin should only light up when left turn is blinking, one pin when right light is blinking. If these check out, then you need to start with the outputs at the end of the adapter. You should see the same results. 12v at lights, left turn, right turn. 

Plug check out OK? something is wrong with trailer wiring. 

Poor ground connections can cause a lot of screwy problems. My Daddy always said, "son, you must be well grounded in life". He must have know what he was doing, because his electrical expertise helped put a man on the moon.


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## Mr Chips (Mar 23, 2008)

utilitylocator said:


> When I plug in the trailer lights to the truck, I get the following results:
> a) the taillights work just fine
> b)the left turnsignal doesnt work but the bulb is good
> c)the right turnsignal makes the emergency flashers come on instead
> ...


 It sounds like your right turn signal is possibly sending a signal to your tailers brake light circut ( this is causing both left and right lights to blink). 

You just need to find out if the problem is in your truck or trailer. The simplest thing to do is find a buddy whose truck has the same round 6 or 7 pin plug as you, and hook your trailer up to his truck. If you get the same results you'll know the problem is with your trailer wiring ( or posibly your adapter), if the lights work as they should, you'll need to look for the problem on your truck. Once you know where the problem lies, you can start hunting for improper connections, bad grounds, or exposed wires


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## kossuth (Aug 15, 2009)

First things first make sure your truck is wired right. Even if it appears to be a factory tow package deal, you gotta make sure the pinouts are ok. It wouldn't have been the first time somebody punched out the knockout in a trucks bumper and installed their own setup and mounted it in the factory position. So grab a test light or a multimeter and verify that the truck is good also, once you verify the truck is good then move onto the trailer. If you know for sure the trailer plug is not a factory deal and is an add on then I would definately make sure stuff lines up. 

Here is a good reference on what your pinouts should be.

http://www.etrailer.com/faq-wiring.aspx


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## utilitylocator (Jan 13, 2009)

Awesome advice everyone! Thanks!! I ended up taking the truck and trailer to a shop. They found and fixed the problem in 20 minutes. The problem was that I ran the ground to the lights to the aluminum case that the lights sit in. I did not take into account that there is a rubber seal between the aluminum housing and trailer frame to stop water from getting in the lights. So the lights weren't grounded.


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