Turn signal issues

[thezentree]

97 4dr Yukon.

My left rear turn signal has been real intermittent. Some days it works, but most of the time it doesn't. It seems that most of the time when it does work, it's after I hit a fairly big bump or something (or like the night I got sideswiped and it worked for 3 weeks), so I started to think there's a short somewhere.

However, this past week I've been doing a lot of towing, and I noticed that the turn signal works properly when the trailer light harness is plugged in. I've replaced the bulb and the circuit board they plug into, and at this point, I don't know what else to do. Help?

 

[1BURBAN]

sounds like a grounding issue if it works when you pull a trailer and intermitently when you don't.

 

[noJeepshere]

X2, grounding issue. An intermittent non-working condition means there is an open somewhere in the circuit. My guess is that since it works fine when a trailer is plugged in, that the open is somewhere on the ground side of that side of the whole rear light circuit, as both tail lights should have a common ground.