Auto battery problem

Ah ha.... We may have found the problem.The next door neighbor needed to haul some new furniture and borrowed me,the Liberty and my 4x8 utility trailer. Me to drive as I'm still on restriction from the hernia procedure. He and his son hooked up the trailer and as soon as they hooked up the lights, one of them came on and this was with the car turned off and the doors closed. OOppsss... I took my little tester light and clipped the ground to the hitch and nothing when I stuck it into the pin holes. I then moved the ground clip to the rear hatch latch and got the tester to light in all three holes. I figgered that since the hatch was open and the interior lites were on, I'd try it a different way, so clipped the clip to the ground wire on the plug and got a light on all three again. Sooo,it looks as if I must have some kind of a short or mis-wired trailer lights. The person that installed my hitch is out of business so I can't go back there. I'll betcha that if it's a bare wire somewhere,that may be what is causing my Brake Buddy to blow fuses. I probably have a hot car also and that's why I get shocked sometimes when I'm getting out.