Ok.. ha I dont know what the deal is.. I do low voltage light installs, run outlets all over my house, inside and out.. yet can NEVER get our trailer brakes right... Ok... heres the deal... stripped the 16' trailer of the two lights.. bought two optronics rear lights.. the only lights in the whole trailer... My truck is set up for a 7-way connection and a 4 flat, and the trailer is a 4 flat... Anway... I think Im confused with the ground wire.. ok so there are two wires going to each light... (forget the colors.. but yellow to one side with a yellow/brown, then green to one side with a green/brown) Btw at this point I have cut the 4 flat off the wires... so everything is bare, so when I attach the yellow to the yellow wire, the green to the green wire, and the other two to the brown, where do I hook the ground to? Does it need to goto each light individually? The only was I get the lights to work now, is to keep the green and yellow wire connected to the corresponding turn signals, and two hook the other two wires to the white ground wire, then the lights will go on with the brakes, as well as the blinkers work fine.. (the brown wire comming from the truck is not connected to anything) But the headlights dont work... when I connect thos brown/green and yellow/green wires to the brown wire (running lights) which I think Im supposed to nothing works at all.. I think I am hooking the ground wire up ocmpletly wrong, but the only way it works is if the ground is run to each light individually.

 

yellow and green are blinker/brake lights.
brown is parking lights.
white is ground.

 

This I knew.. and really didnt answer any of my questions?

 

if you do not hook the white wire up to the trucks ground, the lights will not work.
you can not trust the ground connection to be made through the hitch.
are you mounting the lights to wood, or metal??
trailers use the frame for ground. if you are mounting the lights to wood, you will need to figure out which bolt is the ground point, and run a separate wire from it to the white wire.

 

The Optronics LED lights I installed on my 'toon trailer have short ground wires with ring terminals installed; I drilled a small hole in the trailer frame by each light and fastened with SS sheet metal screws. The factory lights had the ground ring terminals over one of the mounting studs and mashed between the lights and painted frame; it's a wonder they worked at all! The ground from the trailer plug should also be screwed to a clean, unpainted hole near the tongue.

Steve

 

Thanks guys... figured out what was wrong... the only way I could get a ground to the lights which are mounted to the frame was to run a ground wire to each bolt of the light... I think the paint was to thick on the trailer.. Also.. I tested the prong on the trucks side which was suppossed to be the running lights, and it doesnt get juice.. Now the truck is new, so I dont think there is a lose wire or rotting or anything... fuses are all good, is there something Im missing? I guess worst cast it doesnt matter both blinkers and brakes work now., it just doesnt go on with the headlights

 

is it possible you missed one of the fuses?? when i got my 02, nothing on the back worked, neither the 4 pin or the 7 pin. all the fuses were blown. 2 blinker fuses, parking light fuse, brake light fuse, battery charge fuse, switched power fuse.
i test fuses with a test light for power on both sides of the fuse.

 

That brown wire you didn't hook up from the truck sounds like the running light wire you need when the headlights are on. I think one of your main problems is this;
It's ok to "forget the colors" but you still have to know what each color wire does. Touching a small battery charger to the wires on the trailer should get those straightened out, but you need to write down what each wire does. Then you need to get a meter or testlight, and write down what each wire from the truck does. The wiring will not be a mystery once you write down the function of each wire.

For example, you need to use a meter or testlight, and find out what wire is hot with the headlights on from the truck. Then you can proceed to hook it to the trailer.

 

Thanks guys... I did this.. tested and even removed every fuse... I have all the wires hooked up to the lights.. the problem is that the prong (i thik first on top left of the 7 way it is) the running lights... doesnt light with a light tester on the truck side.. i.e. no power to any one prong when the head lights are on. If I could get that one to get power when the headlights were on, everything would work. Just cant figure out why the headlights prong isnt getting any juice on the truck

 

These might help: http://www.accessconnect.com/trailer_wiring_diagram.htm

Steve

 

Thanks.. ive seen all the diagrams... I dont think I am explaining the problem... the problem is the receiver on the TRUCK is not getting the power where it should for when the lights are on.... the trailer plug and everything to the trailer is hooked up right

 

if the trailer plug on the back of the truck is not getting power to the parking lamp wire, than either the wire is cut/broken somewhere in the truck or in the plug.

 

thanks for the replies... I inspected everything... looks fine.. like I said its new, now I know that doesnt mean something cant be wrong, I just doubt it.. I checked all the fuses, but maybe missed one? could this have its own fuse that is different then the other lights in the plug?

 

You didn't say what year truck you have, but I looked in your profile and saw a 2004 f250. So I will assume this is what you are working on.

The parking lamp signal for the trailer plug comes from a "trailer tow relay parking lamp" located in the fuse box under the dash. But we have been here before, don't go looking for the relay. The service manual says it's "not serviceable" and we have had people look for it and can't find it. So we think it's built into the fuse box, and the whole fuse box has to be replaced to repair the relay if it's the problem.

Check fuse #38 in the underdash fuse box. This is the fuse that feeds the relay. If the fuse is good, then check the wire that comes out of the relay and goes to the rear. It is a brown/white wire. There is also a brown wire that enters the fuse box and triggers the relay. If you have voltage on the brown wire going in, the fuse is good, and no voltage coming out on the brown/white, then we can assume the relay inside the fuse box is bad.

If this is the case, I think I would add a bosch type relay and wire it in to take the place of the fuse box relay, and make it all work without replacing the fuse box.

 

Well I figured it out.. checked all the fuses... none were blown.. but heres the kicker.. I checked the fuse you told me to.. and there wasnt one there! HA! explains why a blown fuse wasnt the problem! thanks guys!