i have a 99 monte carlo ls and when i use either my left or right turn signals just the brake lights flash, but when i use the brake while i have one of the turn signals on the brake lights freeze. I have checked fuses and bulbs btw.

 

Hi `Matt & Welcome to the MCF.
Check back on your thread question to see what other member's contribute to your problem.
It sounds to me like you may have a bad blinker switch. (?)
Check the below vid & I hope it helps. * Note, it's for a 95 Monte Carlo, but it should be the same as yours > Good Luck

 

i concur. had this happen to me.

 

Space:
Great Find! Nice Video!
Thanks!