I have a 99 Z34 that the brake lights work part time. It seems that when I first get into the car and start it up they work fine until I'm driving down the road and use the turn signals then they quit. The turn signals work fine and the third brake light works. Any idea what I need to check?

 

Check the bulbs, make sure there's a clean connection. If that doesn't work, it's probably your multifunction switch going bad.

 

Sounds like your multifunction switch located in the steering column. Same thing happened to my 99 monte carlo...had switch replaced...fixed the problem

 

yea, i would agree with the multifunction switch also

 

Mines starting to the same thing...
Someone pointed out that mine was failing...
Its a common problem for 1999...
We had to replace it in my wifes 1999 Blazer as well.

 

my taillights dont work, headlights works just fine

 

You might want to start a new thread, this one is old, and for 95-99 Monte Carlo's...

Check the harness to ensure it's getting power to the bulbs. Do the brake lights work when the brake is pressed?