# Boat Trailer Lighting ???'s



## RiverGulfFshr (Oct 2, 2007)

My left side brake lights nor my left blinker will work. All running lights work on that side but no brake or turn. My question is about my male plug to the truck plug-in. My trailer plug is the5 prong type, not the4 prong which I am used to having. I am basically not using one of the prongs due to the way my truck plug-in is set up. Is that the reasonI am not getting brakes and turn on the left or is it in the wiring?


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## flipjohnson (Apr 14, 2008)

Depending on the truck year and make, check the fuses for the trailer circuits. It would be a good place to start. Also I would purchase a circuit tester at Wal-Mart or auto partsstore (the light type) and test your plug. Real easy way to see what is going on.


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## Tuna Man (Oct 2, 2007)

> *RiverGulfFshr (6/16/2008)*My left side brake lights nor my left blinker will work. All running lights work on that side but no brake or turn. My question is about my male plug to the truck plug-in. My trailer plug is the5 prong type, not the4 prong which I am used to having. I am basically not using one of the prongs due to the way my truck plug-in is set up. Is that the reasonI am not getting brakes and turn on the left or is it in the wiring?


1) use the correct plugs even if you need to make/buy an adapter.

2) Brake/Turn Signalis the same wire

3) As mentioned get a test light and test each terminal and draw a drawing.

I'll post a picture of the adapter I made for my6 prong truck plug and my 4 prong trailer plug.


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## CurtyV22 (Sep 30, 2007)

I also have the incorrect setup but it seams to be working fine so I just leave it alone


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## RiverGulfFshr (Oct 2, 2007)

Thanks for the imput. Deffinately sounds like i am going to get a tester first thing. I will also look into adapters. If I am not mistaked, the 5 prong adapters have one prong for trailer brakes, which I dont have. Correct me if I am wrong.


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## Tuna Man (Oct 2, 2007)

> *RiverGulfFshr (6/16/2008)*Thanks for the imput. Deffinately sounds like i am going to get a tester first thing. I will also look into adapters. If I am not mistaked, the 5 prong adapters have one prong for trailer brakes, which I dont have. Correct me if I am wrong.


There are ONLY 3 wires needed if you use the trailer to truck ball as a ground (lights have to be grounded to trailer). 4 if you use the harness as a ground. I think the trailer brakes use the stop light (brake switch)wire through a brake controller for the brakes. 5 prong for either hydraulic brakesor an accessory. Don't "F" with two different plugs as in a 4 and 5 prong plug, plugged in together. The electrical system on newer vehicles are so touchy it will be easy to blow something, and you DON'T want that to happen. 

A tester is nice to have but you can make one. Wire and a 12V bulb. Connect one wire to base of bulb and the other to bulb terminal. Speaker size wire works well. Easy to make if you have problems on the road away from home.


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## BJW (Oct 1, 2007)

Just as a little help for trouble shooting: the standard color coding for the trailer wires are Green - Right Turn and Stop, Yellow - Left Turn and Stop. 

I don't trust the trailer ball for a ground. I always run aseparate ground wire.The groundgoes through the odd connector on the flat wire connectors: the one male on the female connector (and the one female on the male connector.)Although it is not the problem in your case,it seems that 90% of trailer wiring problems are bad ground. 

As for a test light, I don't know how many times I have taken a bulb and a piece of wire, stipped about two inches of insulation off of the wire, split the strands in half, put one half on one side of the bulb, one half on the other, then twisted the ends together and had an instant test light in 30 seconds - sometimes it seems quicker than finding a test light or meter if I have my electrical box handy.


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## X-Shark (Oct 3, 2007)

> Deffinately sounds like i am going to get a tester first thing.




Check the dang fuse 1st!



You don't give enough info to know what truck you have? Look in the fuse box under the hood, on top of the fender well.



Refer to your owners manual for the proper fuse. Should have 3 fuses for the trailer. Left Stop/Turn--Right Stop/Turn and running lights.



On my truck the Stop/Turns are 10amp fuses and the running lights are 15amp fuses. ['94 F-150]



When I rewired my small trailer, I did away with the 4pin connector. I installed a 7 pin connector. [Only using 4 wires]



The reason is that most all trucks have a 7 pin connector as standard. No more stupid adapter to have a extra connection to worry about making contact. The 7 pin connector fits much better than having all that leverage of the adapter hanging out in the breeze.



The Mako of course has a 7 pin connector on it due to having brakes on the trailer. I've never understood why a 5 pin or 6pin flat plug's were installed on trailers. The only way to hook them up is with adpters.  I know I wouldn't have one.









> There are ONLY 3 wires needed if you use the trailer to truck ball as a ground (lights have to be grounded to trailer)




Never Ever do that. Have you ever followed a trailer that has it that way? You will know when you do. The lights will work great sitting still and flicker all the time going down the road.



Don't use the trailer frame as you ground wire either. Run separate ground wires. 

Note: If you have surge brakes, you will still need a ground from the truck to the trailer frame to operate the brake solenoide when backing up.


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## RiverGulfFshr (Oct 2, 2007)

> *X-Shark (6/16/2008)*
> 
> 
> > Deffinately sounds like i am going to get a tester first thing.
> ...


Sorry, should have elaborated. I know it's not my truck's problem, Chev 2500HD, 2006 model, because my other boat has no problemswith it's lights nor does myflatbedtractor trailer. I have gone throughall connections on my boat trailer but to no avail.


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## X-Shark (Oct 3, 2007)

Then you have a bulb out, faulty connection at the socket or open somewhere in the trailer wiring.



Check the ground too while your there.



Bad grounds are 90% of trailer light problems and why I don't use the trailer frame for the ground, yet the manufactures use it all the time.



The reason is it's cheap and will work long enough to sell the trailer.


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## Tuna Man (Oct 2, 2007)

I don't use the trailer for a ground either (use a 4 wire set up) ...I was pointing out the various wiring possibilities that are out there.

Since you don't know where your problem lies try this.....

How I check the trailer lights is to check the trailer by itself. I will use a battery charger or a battery and two lengths of wire. This isolates the trailer. Easier to find out what works first then trying to figure out all three possibilities...Truck...Connector...Trailer..all at the same time.

Keep in mind that the brake filament will burn brighter then the tail lights. 1 wire will run the tail lights 1 wire will run the L turn signal and a brake light 1 wire will run the R sideand 1 wire for ground as pictured.


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## sosmarine (Sep 28, 2007)

It may have been said already, but I'll put my .02 worth in anyway. Don't worry about the 5th pin. As you said, it is for the Brake lock out, which you don't have. Most of the trailer companies are using the 5 pin plugs now on all their trailers. They don't cost much more and it saves them from stocking two different plugs.


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## bamasam (Sep 27, 2007)

Anyone have a wiring diagram for a 7 pin connector for a Dodge truck to the trailer with electric brakes?


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## Tuna Man (Oct 2, 2007)

> *bamasam (6/23/2008)*Anyone have a wiring diagram for a 7 pin connector for a Dodge truck to the trailer with electric brakes?


Damn Sam, Why didn't you call or PM me. You know I have a Dodge and a 5th wheel.:doh










*White...Ground (10g) <Highlight







*

*Blue...ElectricBrake (12g)*

*Green...Tail/Tag (14g)*

*Black...Battery charge (10g)* You can charge battery in-route

*Red...Left Stop/Turn (14g)*

*Brown...Right Stop/Turn (14g)*

*Yellow...(center) Auxiliary (14g)*


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