It could be something as simple as a fuse, or bulbs, or it could be that something has ethier shorted out you wireing, or something has cut it, you might want to check with you local mechanic, or Chevy dealier.
Answerrelay fuse under hood was culprit still only have right brake lightthe connection between the battery and the brake lights
if the tail lights work but not brake lights then its most likely just a blown fuse or it could be the switch at the top of your brake pedal arm.
check the brake light relay under the hood
A bad brake light switch, and it is bolted to the steering column in under the dash.
Check the brake light switch. It should be mounted on the upper part of the brake pedal or the brake pedal frame. If the brake lights go off when you unplug it you have a stuck or shorted switch.
I am having the same problam on a 1999 silverado have u got any help.
depress the emergency brake. That will shut off the DRLs.
Brake lights indicate when a vehicle is about to stop. When brake lights stop working it is important to check the wiring, the fuse, and the light itself. It could be that any of those need to be replaced.
If emergency brake is on 1 click it turns daytime running lights off. Pull out on emergency brake handle and see if this fixes the problem.
the circuit boards on the taillights are bad.
I found this on my 1997 Silverado and found the connection from the wiring harness to the back OS the switch itself was loose, I could wigle it arouns and make the lights come back on.
replace the relay under the hood Also check brake lights switch had the same problem switched bulbs and worked fine