If the headlights are on and brake lights work but not the tail lights, it is possible there is a short in the electrical wires. Another cause for this could be that the tail light bulbs are burned out. Most vehicles have more than one bulb inside the tail lights to control different lights at the same time.
Brake lights should NOT be effected by the headlights. Brake light function is completely independent of the headlights. Assuming you are not refering to the tail lights, or marker lights, which are supposed to come when the head lights are turned on. Not having brake lights when the head lights are on is a big safety problem and should be corrected.
My rear window brake light works, but not my tail light brakes on my 1997 Monte Carlo. What is the problem?
Since the break lights turn on when the head lights are activated, the problem is probably in the wiring of your break lights. Someone may have accidentally disconnected the wires of your break lights to your head lights.
check the bulbs themselves they sometimes short out internaly & cause feedback also check sidemarker lights I have changed all bulbs and fuses! Wiring problem???
It is possible it is the body control module, I had the same problem except my brake lights worked.
does your car has a separate fuse for the tail light? do the lights come on when you hit the brake.
1 of 3 reasons why, your head lights are on, your reflector lights are on ,or your brake sensor is broken
believe it or not you may haveblown fuse check them.
Well you mean tail lights i think and it has to either they are burnt out or a brake edal sensor is the problem and is stuck
Head light fuse is 20 amp