Originally Posted by 33Willys77
Sounds like when the signal mechanism inside doest not cancel all the way and will not let the brake light to function through. I am assuming you are using the left turn signal when changing lanes. If you push the lever just a little more to the right, it would probably work. Something might be a little too tight not allowing it to return to it's 'home' when you release the lever. I never had one, but I believe they use the GM signal switch - might need a new one if you can not free it. Just some thought here.
Standard 69+GM switch is used in these.
Could try loosening the 3 mounting screws a bit and then snug them up again.
A weak cancel arm may keep the switch from fully returning as well.