Check the brake fluid level in reservoir.
STICKING BRAKE LIGHT SWITCH AT THE TOP OF THE BRAKE BEDAL
The brake light switch located above the brake pedal is broken or out of adjustment.
Check the brake light switch on the brake pedal. Might have to replace it.
check that the emergency brake pedal is completely up.If ok disconnect the electric cable from the emergency brake pedal. i think is brown in color if light turns off the problem is there.
1986
Low brake fluid level or Parking brake not released completely
possibly a bad brake switch located on the brake pedal assy
Bad switch on the emergency brake handle.
Check the fuse, check the bulbs and check the brake light switch.
Brake light switch is located on the brake pedal arm. Unbolt & bolt in new one. Wiring will unplug & plug back in to new switch.
check your e brake
Chevelles never had a third brake light since the Chevelle name was dropped after 1977. However, third brake lights were first installed (and required) in 1986.