I have a friend that bought a trailer for his 2 man bass boat and I went over to help him do a few things today one of which was running some trailer lights. Well we got all of the wires ran and everything hooked up without a hitch. Went to test them out had a problem with the grounding fixed that. Once we got everything connected and hooked up the running lights don't work, the blinkers work, but both blink no matter which blinker you turn on. We read something on the instruction manual about a turn signal converter for certain types. That would solve the blinker issue if that were the case, but still leaves me scratching my head on the running lights. The break lights worked correctly if I recall right. Checked the fuses under the hood with no issues found. Any other suggestions? It is a five wire connector hooked up to a 7 pin adapter.

Well obviously it's wired incorrectly. Yellow is the left turn signal, green is the right turn signal and brown goes to both tail lights. You prob have one of the lights wired backwards. There are plenty of schematics on the Internet to show you how the plug and trailer are supposed to be wired.

The lights are wired correctly I've wired several trailers before. Plus it's not to difficult to match yellow to yellow, those connections were checked more than once.

Maybe the 7 adapter isn't wired correctly? The one I have lets you open it up and change the wires around inside of it. Bound to be it since you're certain the wiring is right.

That would be my guess. As an aside, when in doubt, pull out a can of dielectric spray when all else fails.

Sounds like a test light or the little plug tester would tell.you if its the trailer or truck...

make sure the bulbs are in the light correctly if a bulb is turned too far it will make contact on both turn and park contacts. tail light convertor will only come into play if the truck has amber turn signals and red brake lights (import wireing)therefore needing to put both on 1 function

Turned out to be another grounding issue. The lights were supposed to ground through the bolts that attached them to the trailer even after sanding the paint off they were not grounding correctly. Ended up running an additional ground wire from each light up to the front where the harness was grounded. This solved the issue. Thanks you for the replies.