Check the petal and make sure that the plastic part that touches the brake light switch when the petal is in contact with the brake light switch is still on the petal, if it is missing you will need to replace it, so the petal will make correct contact with the brake light switch.
Check sockets and grounds
Check the fuse for the headlights. It is probably open.
The turn signal switch overrides the brake light circuit while the turn signals are on. If the switch is damaged or worn out the brake lights won't work.
The brake light switch might not be connected properly. Remove the brake light switch for 10 seconds and replace it to its original position.
check wire continuity- no power no lights
You blew a fuse. Check the fuses.
I have a 1990 Chevy 1500 truck the brakelight switch is disconnected and it has no connector going to it. I replaced all the bulbs. And still my running lights are in the on position when i turn off the truck. My brake lights are still not working after replacing the lights. I have a RV brake accuator also under the steering column can you help me solve my problem?
try the multifunction switch located on the steering column .
If the fuses and bulbs are okay I would blame the signal switch assembly. They call it a multi-function switch these days.
the brake switch at the pedal is stuck or out of adjustment.
Did you replace the fuse? have you checked the circuit board well the lights go on cause they tend to short out often
If the brake lights still do not work after replacing the relay and bulbs the fuse may be the culprit. The brake light fuse is located inside the cabin under the driver-side dashboard.