No Brake Lights But The 3RD Light Works

I have no regular brake lights but the 3rd brake light works fine. Fuses are good and I replaced the pedal switch. Is there possibly a problem with the computer? Or maybe a problem with the Maxi Fuse? Can someone help?

Thanks!

You don't mention which car, but on the Sevilles / Devilles, the wiring for the rear brakes runs through the trunk hinge, and sometimes over time that can fray or be worn. Also people have had issues with sockets rusting, so take one bulb out at a time from the brake sockets and check them for rust / shorts.