1995 Corvette Coupe - Third Brake Light Out

The third brake light is out on my 1995 corvette.Can anyone tell me how to troubleshoot and make the repair? If it’s the bulb do I have to go up through the opening above the license plate? Thanks.

You use a wiring diagram similar to this Fig. 22. http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?chapterTitle=Wiring+Diagrams&partName=Chassis+Electrical&pageId=0900c1528008fd94&partId=0900c1528008fdbe To view it, ENLARGE, and press your pc ctrl++ keys numerous times.
“How To Troubleshoot Electrical Sistems” is, also, on the autozone.com Web site. Other information is in the Owner’s Manual, or repair manual…that you don’t have because…?