@chevy88burban, Katelyn , Switch or replace the bulbs from one side to the other to ensure it is not the bulbs, check the bulb sockets for any corrosion/burnt/damaged contacts. Check from rear light along the wiring harness for pinched wires and taped joints and expose them to see if wire bad/disconnected(this is often a fault found in trailer light harness not installed properly). Check all grounds in the vicinity clean and retighten. You still may have to borrow or purchase a test light to probe back through the harness till you find the break in current. Some of the auto parts suppliers offer free/deposit lend a tool like Pepboys, Nappa, Advanced auto parts,etc. may have test light/multi meter and some of the guys are very knowledgeable and may have seen the issue often and put you on the right track also. Link below is a pretty good place to get automotive schematics for your tail light wiring if needed. Good luck. I hope this helped you out, if so let me know by pressing the helpful button.