Most likely a faulty turn signal switch, or possibly the wiring to it.
replace switch assembly.
If you have the same bulb for brake and signal, brake light power needs to be interrupted by the signal lights, The brake circuit has to go through the signal light switch so the problem could be there.
Check fuse, check bulbs, check brake light switch, check wiring and then check signal switch, in that order.
Vehicle side, Brown, running lights Yellow, left signal/brake light Green, right signal/brake light Black, ground Trailer side, white is ground
the turn signal switch is probably bad
Assuming the signal lights still work, no. But a bad brake light switch or a blown brake light fuse could.
The 2001 Chevy Blazer brake lights may not work and the third bake stays on because the current light needs to be replaced. A replacement brake light can be purchased at an Auto Parts store like Pep Boys.
Check the brake light fuse, the bulbs, the brake light switch and last, check the signal switch.
The head light switch is shorting out ,or a bad connection
Check the brake light fuse. If you have 12 volts at the brake light switch I would suspect the signal light switch is at fault.
Check and make sure you have the correct bulb. The turn signal/brake light is a dual element bulb and if you have a single element it does not work properly.
Your brake light is probably brake fluid low or emergency brake on. Rear brake lights are replaced by removing the lens and replacing the dual filament bulb.
I may know the answer if it is a full size Blazer. There is a ground wire for the socket that may be connected to an area that has rusted and no longer is grounded. Reconnect to a solid piece of metal for the light to work.
The brake light switch on a Nissan is located just behind the brake pedal. It sends a signal to the brake lights when the pedal is pressed to turn them on.
You probably have a bad turn signal switch (inside the steering column) if this is a GM.
Above the brake pedal. If your main brake lights dont work but your third center brake light does, then the brake light switch is not the problem. Its is the turn signal switch.
Your question was a little unclear, does the brakelight work when the headlights are off but not when they're on? If that's the case, it's a ground problem. Check the ground to the tail light/brake light assembly. If the brake lights don't work at all, check the turn signal switch. Brake lights are routed throug the turn signal so that you can use the same bulb for turn signal and brake light. BTW, if you have an air bag, don't attempt to replace or inspect the turn signal switch yourself. It can be very dangerous.
Brake Lights Stay on Unless the Brake Pedal is RaisedThis is usually caused by the brake light switch being out of adjustment in its physical distance to the contact point on the brake pedal arm.
i have conected the black and red wire to the brake and it works (the brake light that is) and i conected the blue and white to the signal lights each wire being left and right signal and it all works. but when i brake all of the light lights up the red bar for the brake and the orage bars left and right when i signal left or right whiles braking the signal works but the other signal light sticks on with the brake light. so if any one as any idears please let me know thanks
They are two separate circuits, each has their own fuse. The brake lights not working could be caused by a few things such as a blown fuse, blown bulbs, bad brake light switch, misadjusted brake light switch and depending on what vehicle you have, a bad signal light switch.
Usually in every vehicle the brake lights come on when the brake pedal is pushed in. There is a switch connected to the pedal in some way to make the light switch on.
either dimmer switch or blown fuse If you are saying that the tail brake lights are working but the third brake light is not....It may be a defective turn signal switch in the steering column.
turn signal switch needs replaced!
Check the brake light switch.
Check the fuse, check the bulbs and check the brake light switch, it should be one of those.