So I just purchased my first travel trailer. While hooking up the trailer to my rig's electrical plug we noticed that the running lights are working just fine. They light up, but when I put on my left turn signal it won't respond. The right turn signal responds just fine. I'm sure it has something to do with the wiring and plug. Again the light is not burned out as it lights up when my rig's lights are on it just won't signal. Any ideas or should I just take it in? Thanks in advance for any help.