First thing I'd check would be the fuse for the stop lights. If it is okay the next thing I'd check would be the stoplight switch located under the dash where the brake pedal is suspended.
Turn the emergency flashers on and make sure that they are flashing at a normal rate of speed. Then turn your emergency flashers off and try one of your turn signals and it should work.
Replace the flasher relay.
Probably turn signal flasher
You probably need a new turn signal switch. I have a '96 Monte Carlo and I had to replace the turn signal switch to get the brake lights to work. Thankfully I had a brother who knew how to take off the steering column and replace. Hopes this helps!!!
There are 2 separate flashers.jd
Rear loom ground not contacting. Bulbs burned out or missing. Brake light switch or connection to it is fubared.
Under the dash on the drivers side next to the fuse block. There are two: one for hazard flashers and one for turn signals. They are 1" x 1" square... most likely silver in color.
The 1999 Chevy Monte Carlo does have an emergency fuel cutoff switch. The emergency fuel cutoff switch can be found in the fuse box.
First replace your turn signal flasher as it usually only costs 3-10 dollars; the location varies- many times they are on or near the column under the dash.
The flasher is an integrated module for both turn signals and emerg. flashers. It is located in a junction block that is mounted on the firewall to the left of the steering column under the instrument panel. You have to remove the sound insulator panel and the lower steering column cover to get at it.
Theres this plate at the bottom of your steering colomb, inside it actually, that has the contacts that work all the signals/ brakelights and the like. It apparently wears out after a while. if you fiddle with the turn signal the brake lights will work.you have to take the steeringwheel off and replace the sucker to really fix it. Just watch your tail lights in a store window to see what i mean, shake the turn signal thingy and your lights will work.
It's on the same plug as the hazard flasher, so you have to take off the dash panel, which isn't hard to do. My signals and flashers werent working so I had to take off the panel and put in some conductive gel into the plug contacts to get them working again.