new trailer lights do not work

Trailer related issues and discussion goes here.
Posts: 54
Joined: 27 Nov 2016, 18:53
Location: peru, indiana

new trailer lights do not work

Post by randyo3629 »

2006 polar craft trailer.
picked up the boat..the only lights that worked were the side markers on the tongue.
replaced the trailer harness and the rear lights with LEDs
plugged into the truck...same tongue lights were only ones on.
connected truck to another boat trailer.....all trailer lights work.

cleaned all three ground points.. shiny and tight
reconnected to truck...same result.

here's the kicker...

connected light harness straight to battery.....all lights work, with the exception being the tail lights.
bypassed all the side markers .....same result still no lights.


i've replaced harnesses and lights before and never had this issue.
hope someone can enlighten me.

one thing i forgot to is a pivot tongue and the release pin is pulled out

Posts: 705
Joined: 12 Jul 2017, 21:42
Location: Springfield, MO

new trailer lights do not work

Post by MrGiggles »

Do you have a dedicated ground wire that runs from a good ground on the tow vehicle, to the trailer frame after the tongue pivot? Some even go as far to run a ground wire to each light and not use the frame at all, especially on tilt trailers.

The ball is not a reliable ground, and you cannot rely on a hinged connection either. Should go solid frame on the vehicle, to the plug, and then to solid frame on the trailer.

Check where the lights are grounded too, usually on the studs that hold them to the trailer.

Check the polarity as well. Doesn't matter with regular lights, but LEDs won't work if reversed.

Posts: 2
Joined: 25 Dec 2021, 09:13
Location: 93063

new trailer lights do not work

Post by MrPukaShell »

Check to see if it is a power or ground issue at the rear lights. If it is a ground issue my guess is it is at the pivot point. Try running a ground jumper cable from one frame section to the other. A Power Probe will help in determining what issue you are having. Good luck