my centermount back brake bar light is out and I can't find information on how to replace the bulb.

is it window mounted, or roof mounted. and it is a 2001 Blazer, correct?

i have the procedures for both window and roof mount.

I have a 1995 blazer can you send me the info to replace the 3rd brake light

the whole assembly needs to be replaced. check and make sure you have power to it.