I seem to have a taillight issue with trailers. My left tail light (turn signal/brake light) does not work. The bulb is good as I tested it in the other taillight and it works fine. I just did a rewire with a new harness.

Trouble shooting...

I hooked the wires leading to the left taillight to the right side to see if it was a hardware problem. When hooked in that manner, the right light (turn signal/brake light) didn't work. For all further reference, when I mention that the lights don't work, I'm ONLY referring to the left taillight.

Next, I tried a brand new plug-in that goes to the access panal in the bumper. (The piece the taillight wiring plugs into). That didn't work either. Jiggling the connection doesn't help either.

Next, I plugged into my other boat trailer with the same results (SOL).

The left brake light/turn signal on the 06 Jeep Commander works fine. So, since the taillights on the Jeep work fine, I have to believe the problem is between the light and the plug-in harness.

Anyone else ever have this problem and if so, how did you fix it? I hate to take it in to a Jeep dealer, but if I don't get any ideas, I'll have to bite the bullet and head in for "wallet fleecing".

I personally have yet to test this myself.. But I think you've answered yourself.. Thou if not the harness.. the external connecting pint could have debris in the plugs or have been shorted out with debris hitting or flying up from the road. (which is a common issue)

If you have a tester.. you may need to remove the external harness or outlet and test the wiring.. and you may have to follow the wiring all the way towards the dash.. or towards the tail lights.. whichever comes first.

I've also sent a request that "Haynes manuals" push forward with creating a manual for our jeeps.. this sure could come in handy right about now.. For your wiring project.