led trailer not working

The light have always worked until this morning. I have a Chevy 03 truck with the trailer package which has the round 7 plug in for campers. I bought a new adapter that I have has the test light that lets you know that the plug is working which shows that everything is working. The problem is when I plug in the trailer wiring there is no lights any where plus shuts off the test lights on the plug. Trailer is 2 years old and the wiring looks all intact. Appreciate any help.
Don

Fuses would be my first check. Under the hood as well as on driver side counsel by door

if all of your connections on the back side of the plug in are clean and corrosion free,( I am talking about where the wires are fastened to the plug in )
it sounds like you have a bad ground if it is killing the lights.
the reason I say this is those led testers take almost no voltage to light and it may be lighting up on feedback through the harness.

when you plug the trailer in,the demand is too much killing the lights.
also make sure the trailer is grounded through the plug in and not relying on the hitch for grounding.

If you can try plugging the truck into a different (known working) trailer, that will confirm which end the problem is on.

My boat trailer is LEDs, and over time the wires wore thru inside the trailer frame. There was no way to physically see anything without pulling the wire harness out on each side. I put the new wire harness in split tubing for added protection

Ground! When in doubt check the ground.

I appreciate your help in the problem Will get working on it today.
Again THANKS FOR YOUR HELP dON

nhamm wrote:

Fuses would be my first check. Under the hood as well as on driver side counsel by door

Worth checking but likely not the culprit in this case. If the 7 pin adapter has lights and they are lit, that indicates juice is getting at least that far. Far too many fuse issues in the last couple years and sleeping in trucks for me.

jkarels wrote:

Ground! When in doubt check the ground.

There’s a golden rule.

Also be sure the lighting junction box under the bed is in good condition.

Over the summer I was having some weird issues with my lights. Traced it down to the junction box was cracked and full of water.

My fuse kept blowing everytime I turned my lights on and thus no trailer lights. The culprit was a disconnected side marker light. All the rattling must have shook it loose? Good luck!

Not quite sure if you put on new plug. If you did with led’s you have to have the polarity right. If you hook the Leeds up backwards they don’t work.

Again thanks for all your help. This morning I hooked up my wife’s SUV and the trailer light up like a Christmas three. Now onto my truck problem, the ground was rusty and after a little clean up the Xmas tree light up.
Don Thanks again

For future reference for others, LED lights are EXTREMELY fussy about their ground. Much more so than even the old school incandescent lights. Old incandescent lights would often just get dim with a bad ground, where LED lights are either on or off, they don’t seem to have the tolerance for a bad ground the way incan lights did.

When converting trailers to LED lights, I made the mistake once and only once of trying to ground them off the common. Now I ground each light individually whenever feasible.

Grouse

My 03 Chev has separate fuses for the trailer connector in the underhood fuse block. Every once in a while it pops a trailer light fuse.