Possible ground issue at the taillights.
Break lights come on when you step on the break, they do not come on when the head lights are turned on.
Have you checked the fuses?
You have blown a fuse, look for an acc. fuse out.
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.
Check the fuse for the headlights. It is probably open.
Just pull the parking brake up one click. It won't engage the brake, but it bypasses the headlights.
The brake lights should not come one until you step on the brakes. The tail lights should come on when the headlights are on. If they're weak, maybe there's dirt in/on the lenses or maybe the bulb is old and clouded. Change the bulbs and see if that improves things.
Fuse for parking lights probably blown.
Often this type of behavior is caused by a bad ground for the lighting circuit. Check the ground circuit for the brake lights.
bad connection/short or burnt out brake bulb. Check the harness both under the steering wheel and at the lights.
ummm... your brake lights should ALWAYS work whether your headlights are on or not, that's how people behind you know you are stopping.
Most likely a fuse.
the brake lights are on a separate cuircut,if your brake lights are staying then it will be a fault with the brake light switch. the switch is located under dash,and will be on or very close to brake pedal.
The brake lights and the tail lights are separate circuits. Check the brake light fuse, then check the brake light bulbs, then check the brake light switch.
Is it the taillights or the brake lights? If taillights it may be a wiring problem, If brake lights check the switch on the brake pedal
Check the ground wire to the tail lights.
Check that your hand brake is all the way down. If your hand brake switch is tripped, the brake lihgt should come on, and the automatic running lights won't.
Check the bulbs they are double filamented with smaller being for brake lights
if you recenly replaced bulbs u may have installed them backwards they should be running lights and brake lights if this is the case they maybe installed incorrectly
have you replaced a brake light bulb? if you have a combined sidelight and brakelight you need a double contact bulb. if someone has fitted a single contact bulb, eg an indicator bulb, the terminal touches both the brake and sidelight terminals crossing them out, bringing sidelights on when brake and brakelights when s/lights switched on. hope this helps
if it is your running lights that wont come on, your emergency brake could be on, or the sensor may be reading that it is on. this defeats the running lights. you will know this is happening because the emergency brake light will be on. if this is the case, reach under the drivers side door and with the e-brake off, wiggle the e-brake cable back and forth. the running lights should come back on once the emergency brake cable is in the off position.
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.
Fuse, wiring, bulbs