Okay i just replaced all the lights on my trailer with LED lights. One amber and one red side light on each side of the trailer and then the tail lights. The side lights work fine with some dimming when the opposite turn signal is on. (Please follow me). The turn signals do not work on the tail lights but work fine when I turn on the 4 way flashers. Then when I push on the brake pedal ALL the trailer lights go out until I let off the brake pedal. The package came with a very simple picture/schematic to follow (which I did). Then I put my line splicers in for each of the side lights. I used self tapping metal screws to connect the ground wires to the trailer. This is pretty simple stuff to me but I guess my brain is fried and need a little help.

I believe you have the brake light wire grounded with your self tapping metal screws. Just a simple cross wiring problem. Break out a tester. In the vehicle plug, locate the left blinker wire first. Then locate the right blinker wire.

Ground the proper trailer ground wire to the vehicle ground (usually white but if running a 5 flat plug, it can be mixed up with reverse light). Then attempt to connect each wire to the left until you have the left blinker working. Do the same for the right blinker. When you have the two blinkers working, your breaks and hazards are covered as well. Then turn the blinkers off and turn on your running lights. Try the specific hole on the vehicle that you determined was running lights with the remaining wire or wires. When the running lights are on, you are done with those. Only thing left is reverse lights, if your boat is equipped with an electronic brake release.

The most common problem would be loss of ground. The ground on the vehicle side of the plug should attach directly to the frame of the vehicle (preferably where the wiring harness is grounded). The ground on the trailer side of the plug should extend all the way to the housing of the lights (or ground wire at the light). Never try to ground through the trailer ball or the frame of the trailer, thats a good way to burn up your wiring harness.

mkernan- thank you for your response. There are 3 wires coming out of the tail lights. One is screwed to the trailer and the others yellow and yellow/brown for the left side and for the right side they are green and green/brown. Match the color with the same color on the lights and PRESTO it should work. You think I need to cut the wires and try a different way to put it together? Is this the result of the wiring harness on my vehicle or the one I just bought? The previous trailer we towed everything worked fine on it. Anyways I'm gonna go CUT my FREAKIN WIRES AND DO IT AGAIN....... Thanks again

Thank you sdpfish I am going to check all my grounds before I cut anything. I did just paint the trailer as well and it could be the problem or at least part of it. Still confused as to why ALL the lights go off when I push on the brake....

If you cant get it fixed, I would be glad to look at it. I am just down the road in Florence and have experience with trailer wiring. Just let me know.

It is a grounding issue. Check the ground wire on the trailer AND the vehicle.

Geaduck you have a PM. Now when I cut the wires for the tail lights to switch the wires ALL of the running lights started blinking with the left blinker. Electrical can be so easy sometimes and then so FRUSTRATING at other times.... LOL thanks for all the advice guys. Gonna go out and try to figure this all out later Mike

I had the same problem and after hours of frustration it ended up being the ground wire was breaking down. I just redone the ground on the trailer and it was fixed.

I have checked the grounds and they all seem to have a good connection but nothing seems to work. I'll give it another whirl tomorrow maybe a clear/fresh look will help. Thanks for the help guys. later Mike

Like I mentioned, mine was the ground wire breaking down itself not a bad ground location. I had to run a whole new wire to get this problem solve completely.

Simple: Voltage drop across the rear circuits involved . Brake lights go out because current draw is greater and with better integrety than the boat wiring. White-ground,brown-tail/marker,yellow-left turn,green-right turn. Take your test light to the tail light circuit(as an example)and check to see if it lights. If so TURN THE TEST LIGHT AROUND and check the same using the trailer as the ground. Light on vehicle ok? Light off on trialer-no ground.

I encountered the very same problems you are having. I ran new plug, new wire when I ran the new lights. No MORE BAD GROUNDS.

That all it was was broken ground wires.

Mike, What did you do with the ground wire from the plug at the front of the trailer? I ask because I've seen many people think the trailer will ground through the hitch & 99% of the time it will not.

Just so yall know it is all brand new wiring. The ground from the harness in the front of the trailer is right next to the old grounding wire. The only reason I replaced the lights was because I wanted LED submersible lights so I stopped blowing bulbs all the time. I go fishing in some pretty rough spots and the plastic lenses kept gettin broke and exposing the bulbs. I moved the lights up higher to help with that as well. I put all the new ground wires next to the old ones if not in the same spot. I might need to go and scrape off some paint to help with the grounding issue. Someone stated earlier that the lights were drawing too much juice causing them to shut off when I pushed on the brake. I thought LED were sopposed to use less electricity?? This is all giving me a headache but will make me appreciate it more when I am out on the water and it is all fixed. NOTHING GOES AS PLANNED!! Later guys. Mike