# Solved: Need help wiring a trailer



## BanditFlyer (Oct 25, 2005)

I just recently bought a trailer kit. It's one of those that you have to assemble yourself. I got it mostly assembled and got the lights hooked up. That's when the problem surfaced. I tested the lights by hooking them up to a truck that I had towed other trailers with before. Everything worked fine until I turned on the headlights. When I turned on the blinkers, brakes, and hazard lights, the lights lit up just fine, but then when I turned on the headlights, the lights stopped working. They turned off. No more blinking for turn signals, hazard lights or brakes. But then when I turned off the headlights again, the turn signals, hazard lights, and brake lights worked on the trailer.

Any ideas? Has anyone seen something similar before?

I'm not exactly an electrician, so make sure you enunciate and spell everything out really, really slowly.


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## Guyzer (Jul 3, 2004)

You have a wire crossed somewhere and me not being there ain't gunna help. It shouldn't be a tough one to resolve because the wires are all color coded. If I'm correct you should have a yellow, green, brown and white wire. I can't remember what colors are coming out of the fixtures. Fill me in. Also, make sure you have a good ground as that's very important.


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## Guyzer (Jul 3, 2004)

I just googled and found this........ scroll down to the bottom and you will see a nice color diagram of a 4 way set-up. Follow that and you'll have it whipped. 
http://www.easternmarine.com/em_store/lighting/


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## BanditFlyer (Oct 25, 2005)

Guyzer said:


> I just googled and found this........ scroll down to the bottom and you will see a nice color diagram of a 4 way set-up. Follow that and you'll have it whipped.
> http://www.easternmarine.com/em_store/lighting/


Very cool! :up:

I'm taking a look at it now. My connector seems to have five cables coming out of it - two brown, one yellow, one green and the white ground wire.

From that diagram, it looks like the side marker lights up front should be connected to the brown cables. I don't think my instruction manual had it set up like that - I think mine had me connect the side markers to the yellow and green ones. Which is probably why they worked like turn signals.

Hopefully, connecting the side markers to the brown wires will fix it. :up:


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## Guyzer (Jul 3, 2004)

BanditFlyer said:


> Very cool! :up:
> 
> I'm taking a look at it now. My connector seems to have five cables coming out of it - two brown, one yellow, one green and the white ground wire.
> 
> ...


The brown wires are for all marker / tail / license plate lights. The green ( right ) and yellow ( left ) are for your stop & turn signals. The white is always the ground. What I do for the ground on the trailer is get a sheet metal screw, drill a hole in the frame and attach the wire around the screw, then tighten into frame. I usually use a electrical connector and solder the wire into the connector, then insert the screw. That stops the wire from breaking off... remember the ground is one of the most neglected connections that can cause no end of grief if done in a half hazard manner. Also ensure no wires are able to rub against a sharp edge of the frame. The road vibration will cut through it like a hot knife in butter.

Click the link... I usually use one like the second from the top on the left. The sheet metal screw would be about 5/32" in diam.... whatever that gauge would be. 
http://happyterminals.com/index.php?cPath=21_27_56&osCsid=4hg5mnv33uamjr20tpbfkf2da4

TIP... once you get it all working correctly I suggest you solder all connections and seal with heat shrink tubing. It takes more time but will be worth the effort in the long run. There's nothing worse that having problems on the road.

Let me know how you make out.


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## BanditFlyer (Oct 25, 2005)

Guyzer said:


> Let me know how you make out.


Will do. :up:


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## JohnWill (Oct 19, 2002)

If you have a trailer with combined brake/turn lamps and a truck with separate ones, or the other way around, there's a little module to do the conversion. Basically, it's a bunch of diodes, but it's easier to just buy one. That may be the issue here.


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## BanditFlyer (Oct 25, 2005)

JohnWill said:


> If you have a trailer with combined brake/turn lamps and a truck with separate ones, or the other way around, there's a little module to do the conversion. Basically, it's a bunch of diodes, but it's easier to just buy one. That may be the issue here.


I'll be taking a closer look later on today, hopefully, and post back with more info. Hopefully, just connecting the brown wires to the side-marker lights will be enough to solve the problem(right now, I think I have the yellow and green wires connected there, as per the instructions).

Out of curiosity, anyone have any info on the topic in general? Like a good website to go to for electronics, or electrician-type stuff or whatever larger category this would fall into?


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## Guyzer (Jul 3, 2004)

Um....... stupid question but what more do you need to know other than what the diagram shows?


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## BanditFlyer (Oct 25, 2005)

I don't (or at least, _shouldn't_) _need_ to know any more than that to get the job done. I'm only interested out of curiosity, since I've never done stuff like this(wiring and such) before. I don't even know what broader category the topic falls into - electronics? Electrician-stuff? I don't even know the right name for it. So, naturally, I'm curious to learn more.


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## Guyzer (Jul 3, 2004)

Got it. You might find more if you Google trailer wiring. That's where I got my link from. It's fairly basic stuff though, unless you get into the 7 way stuff which is a bit more in-depth. Then there's the issue Johnwill raised.


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## JohnWill (Oct 19, 2002)

http://www.accessconnect.com/trailer_wiring_diagram.htm

http://www.easternmarine.com/em_store/tech_info/light_tech.html

And here's a whole site on all sorts of different wiring configurations.

http://rides.webshots.com/album/428683237MDvYEN


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## BanditFlyer (Oct 25, 2005)

Here's an update on what I did today:

I connected the yellow and green wires to the front marker lights, and scraped some paint off the spot where the ground wire screws into a "self-tapping screw". The way I had it before was the way the instructions wanted me to set it up, but that didn't work, so I changed it. The way the instructions had me do it was to connect the front two lights to the brown wires. That didn't work yesterday so today, I connected the front two lights to the yellow and green wires. 

Here's what happened. The front lights no longer worked as turn signals, but all the lights still stopped working when I turned the vehicle headlights on.


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## wacor (Feb 22, 2005)

Bandit,

If I missed it I apologize but what is the year, make and model of the vehicle you are wiring up to?

If this is a newer vehicle I am wondering if you need to get a specific wiring harness that connects into the a plug at one of the rear light connections?


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## BanditFlyer (Oct 25, 2005)

wacor said:


> Bandit,
> 
> If I missed it I apologize but what is the year, make and model of the vehicle you are wiring up to?
> 
> If this is a newer vehicle I am wondering if you need to get a specific wiring harness that connects into the a plug at one of the rear light connections?


2003 Nissan Frontier pickup. I got the plug that connects to a connector before the rear lights, and I have hooked up the car to other trailers and it works no problem. That's why I was thinking there's something wrong with the trailer wiring(or maybe one or more of the trailer lights).


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## kiwiguy (Aug 17, 2003)

The symptoms suggest that the lights are not using the ground as a return, but the tail lights circuit instead. That means if the tail lights on the vehicle are not on, all trailer lights work. That means when the headlights (and therefore the tail lights are on) on the vehicle that there is no return possible, evertthing is at +12v, so nothing at all goes.

But a multimeter would confirm this in 30 seconds.


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## Guyzer (Jul 3, 2004)

BanditFlyer said:


> Here's an update on what I did today:
> 
> I connected the yellow and green wires to the front marker lights, and scraped some paint off the spot where the ground wire screws into a "self-tapping screw". The way I had it before was the way the instructions wanted me to set it up, but that didn't work, so I changed it. The way the instructions had me do it was to connect the front two lights to the brown wires. That didn't work yesterday so today, I connected the front two lights to the yellow and green wires.
> 
> Here's what happened. The front lights no longer worked as turn signals, but all the lights still stopped working when I turned the vehicle headlights on.


Bandit the brown wires connect to *all* marker lights. That means the front and the ones on the back. The yellow and green ones connect to the *rear lights only*. One to one side and the other to the opposite side. The yellow and green are your brake / signal lights. If you hook them up any other way it isn't going to work. Something else to check.... make sure you haven't crimped any wires in the frame when you you were putting it together. That would also cause a short which usually blows a fuse. ( but not always )


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## BanditFlyer (Oct 25, 2005)

kiwiguy said:


> The symptoms suggest that the lights are not using the ground as a return, but the tail lights circuit instead. That means if the tail lights on the vehicle are not on, all trailer lights work. That means when the headlights (and therefore the tail lights are on) on the vehicle that there is no return possible, evertthing is at +12v, so nothing at all goes.
> 
> But a multimeter would confirm this in 30 seconds.


From what little I know about this type of stuff, that makes perfect sense. Now googling "multimeter tutorial".


Guyzer said:


> Bandit the brown wires connect to *all* marker lights. That means the front and the ones on the back. The yellow and green ones connect to the *rear lights only*. One to one side and the other to the opposite side. The yellow and green are your brake / signal lights.


That's the way I had it set up initially(I checked yesterday morning before changing anything) and it didn't work. For some reason, with that setup, the front lights were working as turn signals also.


Guyzer said:


> If you hook them up any other way it isn't going to work. Something else to check.... make sure you haven't crimped any wires in the frame when you you were putting it together. That would also cause a short which usually blows a fuse. ( but not always )


There were no wires crimped in the frame so I'm thinking there must be some part that isn't working right, whether that part is one of the taillights or the actual connector. My guess is the connector since the front lights worked as turnsignals when I had the brown wires connected to them. Not sure if that's a logical conclusion to draw in this case. 

This thing is really annoying. I don't think I'm going to do any work on it today other than some googling.


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## JohnWill (Oct 19, 2002)

I think you need to step back and do some thinking about what you have at each end.

What are the connections available from the truck, do you have a specific list of the connections from the trailer connection?

What are the connections from the trailer? Is this a 4 wire rig, or something more complicated?

If you have a list of each side of the connection, and what they're wired to, it would probably be pretty easy. From yourr one message, I'd say the brown connections are for the running/tail lights, and the green and yellow are for each brake/turn signal. Now, if we knew exactly what came out of the truck connector, we could give you a diagram to connect them.

Your owner's manual should tell you exactly what each wire for the truck's trailer connection does, can you post that? Remember those modules I mentioned? Since I'll bet your truck has separate turn and brake lights, you may yet need one of those to wire this trailer to that truck.


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## Guyzer (Jul 3, 2004)

JohnWill said:


> Your owner's manual should tell you exactly what each wire for the truck's trailer connection does, can you post that? Remember those modules I mentioned? Since I'll bet your truck has separate turn and brake lights, you may yet need one of those to wire this trailer to that truck.


I was thinking the same thing but his initial post states he has pulled other trailers with the same vehicle without any problems. If that's the case then his problem is in the trailer set up.


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## wacor (Feb 22, 2005)

This is getting a bit confusing.

So you have a vehicle that has existing wiring and the same plug which has worked to hook up other trailers to?


Have you hooked up to something else that worked before since trying to wire the trailer to make sure that it will operate properly? I would do that first to make sure what used to work still does so that you can rule out there being a problem on the vehicle end. 



If you have hooked something up to confirm and it is ok then it has to be the trailer wiring. If that is the case if it were me I would disconnect all the wire at all the connections on the trailer, remove and inspect the wire and then start from scratch. It sounds like you got something crossed or scraped. The best way is to start from point one.


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## BanditFlyer (Oct 25, 2005)

JohnWill said:


> I think you need to step back and do some thinking about what you have at each end.
> 
> What are the connections available from the truck, do you have a specific list of the connections from the trailer connection?
> 
> What are the connections from the trailer? Is this a 4 wire rig, or something more complicated?


It looks like the top one in one of the links you gave: http://www.accessconnect.com/trailer_wiring_diagram.htm

There are four "pins"(for lack of a better term) in the trailer and vehicle connectors, but the connectors have five wires coming out of them. The wires coming out of the trailer connector are: A white ground, two brown wires(which _appear_ to be behaving like turn signal lights rather than running lights, at least on the front marker lights), a green for the right turn signal and a yellow for the left turn signal.


JohnWill said:


> If you have a list of each side of the connection, and what they're wired to, it would probably be pretty easy. From yourr one message, I'd say the brown connections are for the running/tail lights, and the green and yellow are for each brake/turn signal. Now, if we knew exactly what came out of the truck connector, we could give you a diagram to connect them.


The trailer instructions said that the brown _should_ be wired to all four lights, so it makes sense that those would be the running lights rather than turn signals, but they don't work that way. That's why I'm thinking the trailer connector might have something wrong in it somewhere.


JohnWill said:


> Your owner's manual should tell you exactly what each wire for the truck's trailer connection does, can you post that? Remember those modules I mentioned? Since I'll bet your truck has separate turn and brake lights, you may yet need one of those to wire this trailer to that truck.


Crap, I didn't see that anywhere in the owners manual. I'll check google for info on the vehicle. I'd hate to have to buy an extra part and add even more complexity to it. One of the things I've kept repeating to myself is that this whole thing _looks_ very, very simple - only four lights and five wires, one of which is a ground. But the mess in finding where the problem is seems just about impossible!


wacor said:


> This is getting a bit confusing.
> 
> So you have a vehicle that has existing wiring and the same plug which has worked to hook up other trailers to?


Here's the history of the wiring on the vehicle. I bought an adaptor to plug in before the lights in a spot under the bed of the pickup. Then I towed a rented trailer with it. Then I towed a borrowed trailer with it. Those trailers worked just fine. Then I bought a trailer kit. That's when the problem started. Also, that's the only trailer that it hasn't worked right with.


wacor said:


> Have you hooked up to something else that worked before since trying to wire the trailer to make sure that it will operate properly? I would do that first to make sure what used to work still does so that you can rule out there being a problem on the vehicle end.


Yesterday I drove to a Home Depot and hooked up to two of the trailers they had sitting outside just to check to make sure the truck-side was working. Those trailers worked perfectly so the vehicle itself must be set up right(at least for _those_ trailers - like John Will said, there might be some type of converter I need for the trailer I bought).


wacor said:


> If you have hooked something up to confirm and it is ok then it has to be the trailer wiring. If that is the case if it were me I would disconnect all the wire at all the connections on the trailer, remove and inspect the wire and then start from scratch. It sounds like you got something crossed or scraped. The best way is to start from point one.


Yeah, it sucks. I'm guessing (blindly at that) that there's a crossed wire in the trailer connector or something(maybe a bad taillight in the trailer? One of my friends suggested that the taillights might have been assembled improperly and that might cause a short or something. I don't remember his exact wording, but kiwiguy's post _seems_ to say something similar). I pretty much dissassembled and reassembled all the lights and wiring yesterday and took a look at how the lights responded with various cables plugged into them. The "best" way seemed to be with the green and yellow wires plugged into the front marker lights - the reason I call it "best" is that the front marker lights _stopped_ working as turn-signals when I set it up like that. When I had the brown cables plugged into them, they worked as turn signals just like the rear lights. But regardless of which wires were plugged into the front lights(brown, like the day before yesterday, or green and yellow yesterday), _all_ the lights in the trailer stopped working when I turned on the headlights of the vehicle.

This is a HUGE help to talk about this. The more I sit and type out responses, the clearer it becomes. I would never have thought all this stuff through by myself. Thanks, guys! :up:


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## wacor (Feb 22, 2005)

Here is a typical 4 wire flat plug connection. You do have the flat plug?? 
http://www.classicmfg.com/photos/wire4.jpg

Or do you have this? 
http://www.classicmfg.com/photos/dscn2367-84m.jpg

You got a schematic for what came with the light kit? If so how about scanning and posting it. or take a picture of the trailer plug and pigtail. 
I am not seeing where there should be two browns. Could one of the browns be black? I see it that there is one brown which is RH stop and turn.
The only common is green which is for running light.


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## BanditFlyer (Oct 25, 2005)

wacor said:


> Here is a typical 4 wire flat plug connection. You do have the flat plug??
> http://www.classicmfg.com/photos/wire4.jpg


It's similar to this one, only with five wires coming out of it. I'm looking through various auto parts stores' websites to see if I can find one like it now.

Edit: Here's a setup that looks just like mine:

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=93861

http://www.harborfreight.com/cpi/ctaf/manuals.taf?f=form&ItemID=93861

For some reason, I can't get acrobat reader working, so hopefully that second link provides more detail with the manual.


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## Guyzer (Jul 3, 2004)

5 wires is strange. Besides white,brown, yellow and green what is the 5th color? Can you find a pic of said 5 wire plug and post it?


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## Guyzer (Jul 3, 2004)

What I would do is head on down to the store and buy a 4 wire plug kit and they are cheap. It will come with all the wire you need as well as both ends. Toss the female aside and use the male for the trailer and start fresh by wiring one light at a time to see where the problem is. Something is fishy in Denmark as trailer wiring is very basic stuff.


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## BanditFlyer (Oct 25, 2005)

Guyzer said:


> 5 wires is strange. Besides white,brown, yellow and green what is the 5th color? Can you find a pic of said 5 wire plug and post it?


There are only four colors - two of the wires are brown.


Guyzer said:


> What I would do is head on down to the store and buy a 4 wire plug kit and they are cheap. It will come with all the wire you need as well as both ends. Toss the female aside and use the male for the trailer and start fresh by wiring one light at a time to see where the problem is. Something is fishy in Denmark as trailer wiring is very basic stuff.


I called the store headquarters and they said they think it's probably a bad ground. I told them that I tried it with the ground wire connected to various parts of the frame and that I scraped the paint off where it's supposed to connect. They said that they would ship me out a new connector with all the wires, but it will take a while. By the time it gets here, the 30-day return policy will have expired on the trailer. So your idea to buy the kit at a store sounds good.


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## Guyzer (Jul 3, 2004)

Bandit part of the bad ground issue could be with the light fixture(s) themselves. The ground to those is actually built into the fixture and when attached to the metal trailer it completes the ground. Thats why you don't see a white wire coming out of the fixture and you only connect the " hot " wire. Did you install the lights and if so made sure that the bolts/nuts would be contacting bare metal and not a painted surface?


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## wacor (Feb 22, 2005)

Guyzer said:


> Bandit part of the bad ground issue could be with the light fixture(s) themselves. The ground to those is actually built into the fixture and when attached to the metal trailer it completes the ground. Thats why you don't see a white wire coming out of the fixture and you only connect the " hot " wire. Did you install the lights and if so made sure that the bolts/nuts would be contacting bare metal and not a painted surface?


If he wired it right and it was a matter of the light fixture not being grounded to the frame then I would expect the light trailer light could not work at all. As he can get the light to do some things and his headlight acts up I doubt it is the fixture not being properly grounded.


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## Guyzer (Jul 3, 2004)

I was thinking the same thing but mentioned it as a " what if covering all bases sort of thing. "
I've wired many trailers in my life and am overly fussy about how I go about things because I don't like to do repairs on the road. Kinda anal about those things. ( I'm thinking there is a fault inside one of the light fixtures )


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## wacor (Feb 22, 2005)

Guyzer said:


> ( I'm thinking there is a fault inside one of the light fixtures )


I am thinking he has screwed things up and miswired.

There is a self help thread somewhere around these parts that should fix that.


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## Gabriel (May 2, 2003)

Could mismatched wire guages cause a problem with this type of wiring?


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## JohnWill (Oct 19, 2002)

Unless you overload the wires. wiring two different size wires together isn't an issue.

I really think you have to determine exactly what you have on the truck before you can intelligently attack this issue. The fact that other trailers have worked isn't that significant, unless we know for sure they're wired exactly like this one.


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## BanditFlyer (Oct 25, 2005)

Anm update - we got replacements for all the electrical parts. Then, before beginning assemply with the new parts, I tried out the new lights and cable with the ground wire plugged directly into the white cable on the pickup end of the electircal connector. I tried this with all the lights, one by one, and they all worked. So I attached the lights and made sure to ground each of them individually to the white cable(bought a 24' extension cable to do that), and EVERYTHING WORKED!

Thank you for all your help guys! I really could not have done it without you guys. :up:


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## JohnWill (Oct 19, 2002)

Glad to see you got it going. Now you're a trailer wiring expert! 

*You can mark your own threads solved using the thread tools at the upper right of the screen.©*


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## DSPRING (Sep 30, 2007)

My vehicles all have integrated turn signals/brake lights. The electrical plugs for connecting trailers are standard 4 wire. I have 2 trailers with separate turn signals and brake lights( there are no trailer brakes on these trailers) with five wire plugs. One wire for turn signals and another for the brake lights. How do I connect the my vehicles to these trailers? All converters I have found seem to go from 5 on the vehicle to 4 on the trailer, but not the other way around.


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## JohnWill (Oct 19, 2002)

Since the brake light and turn signal are integrated on the incoming line, there's no real way to separate them. However, if you just don't connect the brake line line, the turn signals will do both jobs. I suspect that both brake lights are wired together on the trailers, so a direct connection is not possible. You could also rewire the trailers... 

I suspect that a buffered device that separates the signals and senses if the brakes are on would be required if you want to keep the wiring intact.


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