I can help you I had that problem on my 1988 cutlass ciera and the answer is that one of the lights on the back not the third small on is not working. Open the trunk take out the bulb itself and check the wiring. That what was wrong with mine someone didn't have it wired right. Hope this helps you out.
Check the brake light switch. It's under the dash, connected to the brake pedal. If it's adjusted wrong or faulty, it could cause the brake lights to stay on. If you can use a meter and tell that the brake light switch is ok, next test the turn signal switch. Sometimes they short out and leave the brake lights on. You'll have to pull the steering wheel to do that.
Check the switch on the brake pedal
Stuck brake light switch.
If the tail lights were hot during the swap you may have broken the filiments. Bumping a bulb that is on or been on recently can cause the filiments to fail. Remove the bulbs hold them up to a light and see if the filimant is intact.
brake light switch would be most common cause
The BOO (Brake On/Off) Switch may need to be replaced. If it is bad, it would cause the brake lights to NOT illuminate when the brake pedal is applied.
BAD BRAKE LIGHT SWITCH AT TOP OF BRAKE PEDAL
Possible ground issue at the taillights.
Blown fuse or defective brake light switch.
The most likely cause is a bad brake light switch (if none of the brake lights illuminate) but if its only one of the brake lights, try changing the bulb. Even if they still work as running or turn lights because they have a double filament and may still work partially, but not as brake lights.
It's probably your'e brake light switch sticking ,i think it's down under the brake pedal connected to the pedal try pulling up on pedal , check switch,unplug it see if lights go out
Most likely a fuse.
Check your brake light switch at hte brake pedal.
More than likely it is the brake light switch that is attached to the brake pedal.
You probably need to replace your brake light switch. It's near the top of the brake assembly, beyond a trim panel. The fact that all three brake lights don't work rules out problems in the multifunction switch (the cause of similar problems affecting only the two rear lights.)
every vehicle must have brake lights to indicate that the vehicle is stopping. with no brake lights the vehicle can cause a rear end collision.
brake switch located on the top of the brake pedal
This is usually cause by a stuck brake light switch on the brake pedal. Replace it.
Could be a bad wiring harness, disruption of the circuit somewhere between the brake pedal and the brake lights, a bad switch which fails to actuate the brake lights. See sources and related links below for bulb information.
A loose or corroded ground wire will cause the fuse to blow. Check the ground wires on your brake lights.
The most common cause for brake lights to be out on a 2001 Mustang GT is a blown bulb. There are some instances where there is faulty wiring.
bad switch on brake pedal? do you have brake lights?
The most probable cause is that the brake light switch is out of adjustment.
Nonfunctional Brake LightsOne possible cause of this issue is that the brake light switch is not adjusted properly, or the switch could be defective.