Looking at the Autozone "repair guides" ther is a relay for the 3rd brake light, but offers no help on its location.
The brake light switch relay for your 1997 Chevy truck is located beneath the drivers side dashboard. The brake light relay switch will be above the brake pedal.
There is more than one relay, be more specific. Third Brake light
It is located on the brake pedal arm under the dash.
The 1991 Volvo brake light relay switch is located beneath the drivers side dashboard. The brake light relay switch will be above the brake pedal.
Where is the left rear brake and turn signal relay located on a 2010 Chevy express van. V-6
There is no brake light relay. There is however a brake light switch located above the brake pedal.
Changing the brake light relay switch on your 1999 Chevy Cavalier is quite easy. The brake light switch simply plugs in and out.
As far as I know, they are not on the same fuse/relay.
where is the daytime running light relay located on a 2002 chevy cavalier
under the hood in the fuse/ relay/solenoid box
Change out the flasher relay located under the dash. Not the brake light switch which is activated by the brake pedal. Replacing the relay should solve the problem.
Think it's on the brake pedal close to the top