As Joe pointed out, they are usually controlled by a rheostat. I know that this is going to sound kinda convoluted, but most chassis have the brake lights tied into the dash lights and a notification to the operator that that there is a problem. Make sure that the rheostat is getting power. A single light bulb wouldn't stop the rest from working (light a Christmas tree).
Kelly and Jerry Powell with Halo (Lethal White Aussie), Nash the Rat Terrorist, and now Reid, the "Brindle we have no idea puppy"
2020 Grand Design Solitude 390RK-R