So I am in the process of finishing up a small trailer project and I just finished running the lighting wiring down the frame of the trailer. All connections are soldered.

Here is how its wired...



I can't seem to get my amber markers or my rear markers to light up.

To make things worse... Right Rear and Left rear work as intended, turn signals work and flashers flash... If you hit the brake on the vehicle the brake lights come on the vehicle but it kills all power to the trailer lights period until you let off the brakes.

If the diagram is confusing... Brown was used for the amber markers and the rear 3 marker lights. Brown was also used for the left and right rear lights. Green goes to the corresponding turn signal and yellow goes to its corresponding turn signal.

Any insight?

Would a bad ground connection cause my issue?

 

I would suspect bad ground connections at the light fixtures, a very common problem especially when the brake lights kill the others. I have seen this problem many times over the 50 years I have been fixing automotive electrical systems. I would check the ground at each light, even the ones that work. One trick I have used on lights that are grounded just by a screw going the base of the light is to clean a very small spot on the trailer around the mounting hole, the one that grounds it, and then use a star type lock washer between the light and trailer.

 

So, just to be sure I am on the same page, you tested your wiring with a booster battery or similar and it doesn't work (leaving the truck out of the equation)? I see where you pulled the wiring diagram off the Internet. https://www.google.com/search?q=trai...atETmhkfMEM%3A

Steve

 

I have a spare 12v RV/trailer battery that I tested with... Yes, I pulled the wiring off the internet, I used it as a guide to wire my trailer.

 

So all is fine until tied to the truck or also with the battery alone?

 

I figured it out... It was bad grounds all around. Wire wheel and ran new ground wire to the trailer and its fixed.

Thanks fellas.

 

Glad you got it. I wasn't clear whether it was just when connected to the truck. Good model for current flow is water. It goes to the best connection or point of least resistance. Sounds like the brake lights were the ones.

Steve

 

Glad you figured it out, but was going to say before I saw it, that in my 10 years or so of pulling various trailers, everything from a really nice (and WAAAAYYY TOO BIG AND HEAVY FOR MY OLD CHEVY ASTRO VAN!) open trailer my friend had that I used to haul some landscape blocks, to an old Jayco pop up camper chassis stripped of the camper and voila! its a trailer! I'm 99.9% sure that EVERY time I've had a wiring issue that didn't make sense-IT WAS A BAD GROUND SOMEPLACE! That can also be a bad ground on the tow vehicle as well!