I've been trying to look up the schematics. My rear passenger brake light won't work, I've replaced the bulbs and fuses. I was told the problems probably with my ground wire, that it's either corroded or loose. I've looked everywhere online to try to find the schematics but have no luck. HELP please...

My right rear break lights are out. I've changed my number 4 fuse for the break lights, and replaced all the lights as well. It worked fine after that for 4 hours and now doesnt work. I figure wiring might be the problem. If it's possible I'd like to fix this myself, so any advice would be appreciated