Ok, here is the long & short of it:

1) Free 6 x 8 utility trailer
2) Needs to be re-wired
3) Buy wiring kit & new tail lights
4) Install kit & lights
5) Lights work but.......
5a) Turn blinker on both lights blink, one brighter than
the other
6) Check ground, looks good to me

Standard four wire plug, yellow, green, Brown, white.
Yellow left Turn, Green Right Turn, Brown lights for
both tail lights, white ground.

Suggestions? I know its not rocket science, its a trailer for crying out load.
I wire brushed a spot to connect the ground wire from
the plug to the trailer, drilled a hole, and bolted the wire to the trailer.

My lights on my truck work fine so I wouldn't think its
a grounding problem with my truck.

The wiring kit for the trailer, is it a 2 way or 4 way set? Most cars today use 4 lights (breaks separate from signals), while the trailer may only use 2 bulbs - combined brakes and signals.

You may need to go to u-haul and get the cross over kit to go from 4 way to 2 way...

James

Its a two way set. Thanks for the info. I will see what U-haul has.

Do a Google search for trailer wiring. There are diagrams on line that can help.

Paul

make sure your bulbs are installed correctly. they might need another 1/4 turn or a good cleanning. little vinegar on a q-tip.

Check bulb wattage. Might be off by 5 watts...