I put led tail light on my 2005 tahoe and now my third brake light does not work???

Usually if the third brake light works but not the regular brake lights, the problem is inside the turn signal switch.

http://wiki.answers.com/Q/Where_is_the_fuse_for_the_third_brake_light_on_a_2005_Chevy_Tahoe

switch is bad

Since the high mounted brake light works you know that the brake light switch is working. Now you need to check the brake light bulbs in the rear tail light assemblies. The brake lights are separate from the tail light (parking or running lights). There are two screws that hold the rear light assemblies in place.

your brake light switch is the problem, check the fuse first.

I've worked on these the first drove me crazy. its the turn signal switch every thing runs thru these. head lights, turn signal, brakes. except the third brake light. it runs directly from the brake switch. go figuare

If you have LED lights that are not 12 volts dc take them back thay have LED replace lights that replaces your regular light to LED.

centre top light cluster is led unit and you will have to replace whole unit.sorry .i fx em not build em

you have a broken wire some were if you cant find it you can run a seperate power wire from the third brake light to the brake lights but i would check for power at the brake lights first to make sure its not a ground problem

bead brake light switch