brake lights out

So about 6 months ago my brake light just stopped working. The reverse lights & blinker lights still work. Its not the light bulb because I've changed them and nothing happened. About 5-6 years ago I had a stereo installed, that's the only cause I can think of.
Just wondering if anyone had any ideas and what I might be able to do to fix them......hopefully I can do it myself, if not it seems like it would be an expensive fix. Any advise would help...thanks.

 

I don't know but I have the same problem but it's only the reverse lights that don't light up when in reverse. Do you have a trailer harness or wiring for a cap? Maybe a loose ground? Thats what I tried so far

 

I do have a trailer harness. I don't believe I have wiring for a cap. The trailer harness was already on the truck when I bought it new in 07. Where do you check for a loose ground?

 

have you checked the fuse?

 

Remove the tail light, make sure light socket is clean, have a buddy press brakes, test socket with multimeter. No power? then follow wires from that brake light making sure they are not damaged. No damage? check and see if the trailer harness is hooked up to them. If it is, check connection. If it's not soldered, take it apart, solder it, shrink wrap and electrical tape. If on the wires there is green/white corrosion, cut affected areas out and solder. Hope this helps.

 

Have you checked your brake light switch? It's located under your brake pedal. Unplug the small wiring harness that goes into it. It a blue plug with four wires that is plugged into a white switch. After removing the blue wiring harness give the white switch half a turn and pull down. That is your break switch you can either replace it or take it apart and clean the contacts as I did.