# Help with trailer wiring



## itmustbeslim (May 7, 2011)

Ok so here is where I am at after my work today: I know this is a repost but I was hoping to try and resolve the issue this weekend.

I pulled the old wires and ran new wires from the pigtail back, wired a new pigtail and connected the new wires to the lights. I connected the front ground to the tongue and tried to connect a ground to the back of the lights. So far I still get nothing, which makes me think it may be the lights themselves or at the very least the grounding of the lights. Here are some pictures:

This is the view of the lights from the back:






Another view of the lights:





Here is a view of the ground I made for the lights, because the lights are elevated a attached the ground at the bottom to the trailer frame, which I have since changed and shortened:





Here is the pigtail with the ground in the background:





Here is another view of the front ground:





Before any ground screw I used a cone grinding attachment and took all of the paint off at the ground site and used #10 self tapped screws. If you'll notice I didn't match the color of the wires up because I did not want to have to buy a whole other roll of wires.

The weirdest part is what happened after I connected the car to the trailer. Without connecting the car to the trailer I tested the car harness and the correct posts are firing when turn signals etc are turned on. After I connected the trailer and turned on the left or right turn signal all 3 wires on the trailer were showing voltage blinking but still not lights (using a circuit tester). Why would this happen? I even checked the ground on the car just in case.

Do I need to replace the lights? The bulbs seem fine.

I am not sure what is happening so any help or direction would be much appreciated, this is very frustrating because it should be so simple and yet just out of reach.


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## chuck in nc (May 8, 2011)

The white wire is DC Common. It MUST be at the same potential as the car/truck frame (common of car battery or "-" terminal).

Maybe the supply plug from the car is NOT wired to the car frame? Normally the trailer ball connection will make the common connection for you but that will not happen with the trailer tongue off the ball. Connect the trailer to the car and see if it works. If so just make sure the supplied DC Common on the automobile side of the harness is grounded to the car frame. 

An easy check/bypass is to run a bare wire from your trailer tongue ground point to the car frame - pick a point that has bare metal on the car frame.

Carrying the white wire to each light is more reliable than depending on the trailer frame for DC common distribution. But the trailer frame will work so long as you don't have any points where the conductive path is broken between the trailer light connections and the main (tongue) DC common connection.

Hope this helps.

Chuck


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## itmustbeslim (May 8, 2011)

OK, so if I used the white wire that came in the wire roll as a turn signal connection, it won't work? I need to use the white only to ground and that's it?


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## TNtroller (May 8, 2011)

also suggest you put the other nut on the lights to secure them to the trailer. you may have an open circuit if you don't tighten both nuts/bolts on the back of each light down snug.


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## chuck in nc (May 8, 2011)

itmustbeslim said:


> OK, so if I used the white wire that came in the wire roll as a turn signal connection, it won't work? I need to use the white only to ground and that's it?



I am not sure what you mean when you are referring to the white wire. If the white wire in the roll is physically connected to the trailer harness plug terminal with the white wire then it will not work as a turn signal "+" connection. That white wire connection point must be tied to the trailer frame or used as a DC common.

You can run any color wire you want to make the connections from the trailer harness to the trailer lights but the connections must be made according to a 4-wire harness diagram.

I found this on Ask.com:

Trailer Wiring Colors:
Brown wire to the tail or parking lights
Green wire to right turn signal/stoplight
Yellow wire to the left turn signal/stoplight
White wire to common or chassis ground

My earlier post reference was to make sure that the white wire on the automobile connector (the one permanently wired on the car that you plug the trailer connector into) was wired to the automobile frame or straight to DC common (- terminal of the automobile battery). If the DC common connection was not made on the car then you will not get a completed electrical circuit unless the trailer is physically coupled to the car (like it is when you are pulling the boat). I have seen a few occasions where whoever wired the car side of the connector did not tie the common port to DC common on the car. The lights work when the trailer is connected but not when the ball/hitch is uncoupled.

Hope this helps.

Chuck


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## crkdltr (May 9, 2011)

Do you have a test light? If so, use it to make sure the contacts in the light housings are hot. 

Since you got the new harness, I assume you also got the shorter harness for your vehicle? If so, hook it up to one of your batteries to use instead of having to hook the trailer up to your car every time. That way you can hook the white wire to negative and the green/brown/yellow to positive and have a hot plug to hook to the trailer harness. By doing this you can troubleshoot one wire at a time.

You mentioned in my thread that you thought you didn't have a tilting trailer. Can you take a picture of the trailer where the tongue of the trailer intersects with the frame and how those posts are connected to the frame? Posting those images may help us to direct you where to further troubleshoot. 

Have you tried hooking the lights directly to the battery? (You will have to use a small jumper wire to ground the studs of the lights to the negative post of the battery). If they work then you can rule that out.


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## itmustbeslim (May 9, 2011)

Ok, so I used terminal connectors instead of wrapping the wire around the light housing like so:






This time I put the trailer on the ball, connected the wires and turned on the headlights and signals. This time the correct poles lit up on my tester on the car end, but on the trailer pigtail all the wires were lighting up, as opposed to the brown and the turn signal that was on. With brand new wires, new grounds, and new wires in the car (I even moved the car ground screw just in case), the only wild card are the lights themselves. I do not have the adequate tools to test whether the lights are even functional or not so I think I will buy new lights tomorrow and install them, if those work then I have won the battle, if those don't turn on I may just start sobbing like a baby. I mean seriously, there are only 4 wires, it is so frustrating that something so simple can be so difficult. 

So give me some advice. Obviously I am getting some signal to the trailer but it is being distorted, hence my feeling that it is a ground issue. Does my terminal rigging seem adequate? What would you do in this situation? I am at my wit's end.

Thanks for all your help thus far.


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## chuck in nc (May 9, 2011)

crkdltr said:


> Do you have a test light? If so, use it to make sure the contacts in the light housings are hot.
> 
> Since you got the new harness, I assume you also got the shorter harness for your vehicle? If so, hook it up to one of your batteries to use instead of having to hook the trailer up to your car every time. That way you can hook the white wire to negative and the green/brown/yellow to positive and have a hot plug to hook to the trailer harness. By doing this you can troubleshoot one wire at a time.
> 
> ...



+1

Easier to check things one at a time.


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## crkdltr (May 10, 2011)

itmustbeslim said:


> So give me some advice. Obviously I am getting some signal to the trailer but it is being distorted, hence my feeling that it is a ground issue. Does my terminal rigging seem adequate? What would you do in this situation? I am at my wit's end.
> 
> Thanks for all your help thus far.



Did you remove the light poles from the frame and clean the area where the two pieces make contact? You could have bad grounding there due to age/rust/paint. I actually liked that you had the extra ground from the lamp stud to the trailer. 

Also, looking back at your pictures... why do you have the left turn signal wire (yellow) attached to the right tail light running light (brown)?


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## itmustbeslim (May 10, 2011)

Well, stupid me, (by the way I went to law school and this is one of the most technical things I have done) I bought a wiring kit from autozone and instead of just going to Ace to buy an extra length of brown wire, I used the white wire that came in the 4 wire roll as my right signal running light wire. So I went green to green, yellow to yellow, brown to brown on one side and white to brown on the other. When I got to the pigtail I just wired the white and the brown in to the same butt connector that went to the brown wire on the pig tail. Some people seem to think using the white as a signal wire won't work others seem to think it does not matter, any thoughts?

As to your other question I took a cone grinding attachment for my drill and ground off the paint and the rust in the post holes and where I connected the ground terminals.


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## lckstckn2smknbrls (May 10, 2011)

You need to follow the color coding.


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## chuck in nc (May 10, 2011)

itmustbeslim said:


> Well, stupid me, (by the way I went to law school and this is one of the most technical things I have done) I bought a wiring kit from autozone and instead of just going to Ace to buy an extra length of brown wire, I used the white wire that came in the 4 wire roll as my right signal running light wire. So I went green to green, yellow to yellow, brown to brown on one side and white to brown on the other. When I got to the pigtail I just wired the white and the brown in to the same butt connector that went to the brown wire on the pig tail. Some people seem to think using the white as a signal wire won't work others seem to think it does not matter, any thoughts?
> 
> As to your other question I took a cone grinding attachment for my drill and ground off the paint and the rust in the post holes and where I connected the ground terminals.



Electrically it doesn't matter if you use the white wire as a feed for the tail light. Some would mark the wire with a magic marker or brown tape but it is easy enough to see the butt splice at the harness.

Did you get this thing working?

Keep it up we're gonna start with the lawyer jokes! :LOL2:


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## itmustbeslim (May 11, 2011)

*Success!*

So I got so angry the other day (my wife will verify) that I was in a downright pissy mood. In fact I got so angry that I ripped out all of the wiring and started over, with the same new wires. Matched everything up, and got it all in just before a massive thunder storm hit. Today I had a couple of hours so I cut everything off too, pigtails grounds etc. and brought out my deep cycle to begin testing wire by wire, and tested each light individually. The lights worked fine so I moved to the wires. I found that every wire was registering hot so the only problem left could be the grounding, which is weird since I did so much with the grounds, setting new holes wiring etc.

So what I did was I ran a ground wire all the way from each light to the ground spot on the front of the trailer where I grounded the pigtail and voila! Lights!

So I am surmising that 2 things are probably happening: I never paid much attention to the fact that the tongue of my trailer is black while the back half is white. This tells me that the guy I bought it from replaced one of the two sections and both sections were painted which means no matter where I grounded it on the back 2/3 of the trailer it would never ground enough. The other thing I think may be happening is the trailer is not metal (not a very convincing theory) But if OJ could sell himself as an upstanding citizen that did not kill his wife or Ron, then I have enough circumstantial evidence to sell a jury that the trailer is not metal.

Either way it is a flippin relief to see those lights light up. I think what I will do is run a ground wire from each light to the front ground point, then over the winter take the trailer apart and re do it. The thing I am most pissed about is that I will have to pull the wires again to run the ground wires nicely.

Thanks for all your help.


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## lckstckn2smknbrls (May 11, 2011)

I loop 1 ground wire to all the lights and then back to the front of the trailer.


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## RBuffordTJ (May 13, 2011)

Holy Cow! I'm tired after reading this...lol. I'm glad you got it figured out, chasing ground problems can be a royal pain in the defense attorney! :shock: Oops, did I just type that? :wink: 

Just having fun with you man, now go catch some fish!
Bufford


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## pelagicbldr (May 17, 2011)

Thanks for the info. I can build anything but don't ask me to wire a thing!


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