2nd Gen Non-Engine/Transmission Post-gauge install problems

[AFoulk]

installed my gauges yesterday (boost,pyro,fp). Afterwards, I turned my lights on, and noticed that my left, outer clearance light was out. I changed the bulb and nothing. I used a volt meter to check for power and had none at the socket, so I thought maybe I pulled a connection out when putting the apillar and gauges together. Well, the power supply wire is fine from the wire tap up to under the head liner. Besides all the other clearance lights work. The goofball that had the truck before me actually had the clearance lights wired up to the dimmer switch. When my buddy was helping find the power coming out of the dimmer for my gauge lights, my clearance lights were getting dim and getting bright with the dimmer switch! I found my parking light power supply coming out of the headlight switch and wired that into a relay I mounted under the hood for the clearance lights. Anyways, I thought, heck, maybe he ran a power supply for the rest of the clearance lights up the pass. side a pillar. nope. So I'm guessing its either the socket or the wiring somewhere under the headliner. So, my main question is, whats the procedure for dropping the headliner?