Top Brake Light Diagnosis A Comprehensive Toolkit

The third brake light is LED-based and is fed by a separate wire. The problem that you're having is most probably faulty light switch (A3a on ... Are the tail light bulbs dual filament with the brake lights using same bulb, are you sure both bulbs are in sockets properly and not bridging ... The only way to turn off the third brake light is to remove the fuse #49. Both of my regular brake lights work correctly but the third brake light doesn't. The main brake lights are always on when my headlights are on. Not the third brake light on the cab, just the two tail light portions. Bad brake light switch...it is sticking closed, keeping juice running thru the circuit. I believe it is behind the brake pedal and hopefully ... Also check the brake fluid level see if it is too low. I remember too low brake fluid level will also turn the warning light on. Top ... Possible the switch at the brake is bad. Have you unplugged the connection to it to see if it turn off. It may go out but but still may not be ... First thing to check is the brake light modulator, it's not a factory part and may have shorted internally, or maybe a problem with it's wiring. Pull the tails and check the bulbs, if they are the correct type make sure they are seated correctly and not burned out, if they are LED's take ... My 3rd brake light was on, not full bright, but maybe 25-50% of its power. When I apply brake, it came 100% with 2 side brake light and when I release brake ...