I would suspect a poor ground connection at one of the left turn signal lights. Disconnect the battery, remove the bulbs and clean the light bulb sockets. Look for any loose wires.
flasher has gone bad and needs replacing.
Have you ever stepped on the brake when the flashers are flashing and see how they stop flashing? So yes the circuit does go thru the flasher, so replace that and see.
Most likely it is either the brake light switch, under the dashboard, connected to the brake pedal or the turn signal switch inside the steering column.
It' likely, if bulbs are OK that the turn signal switch is burned out. If the switch fails, it won't allow the brake light signal through to the brake light wiring. Go to:http://www.2carpros.com/first_things/no_brake_lights.htm for the 4 page analysis. See: "(American Car) Both Lower Brake Lights Not Working" To determine if the switch is bad test the incoming and outgoing current. If brake light switch power is present at the turn signal switch but not at any outgoing brake light wires, the turn signal switch has probably failed. This is a Buick design issue because keeping your foot on the brake or if the brake switch sticks keeping the brake lights on, the circuit will fail due to amperage overload.
How to change brake lines on a 1991 Buick Lesabre?
If the left turn signal light on your 2002 Buick Park Avenue is not flashing, it could be due to a burnt-out bulb, a faulty turn signal relay, or an issue with the wiring. Another possibility is a malfunction in the turn signal switch itself. Checking the bulb first is a good step, as it's the simplest fix. If the bulb is functional, further diagnosis of the relay and switch may be necessary.
Double-check me on this that the rear turn signal uses the brake bulb. That bulb is a 3057. See sources and related links below for more info.
If you are asking about the hazard flashing unit, it should be located on the steering column brace. The turn signal flasher should be located on the left side under-dash panel, retained by a spring clip, or near the fuse box.
I have the same problem- press on the brake, no brake lights. Press on the brake and pull back on turn signal/high beams lever, brake lights turn on! Jiggle the lever, brake lights turn on, but left turn signal does not work. I have replaced the switch that is down near the brake pedal and that is not the problem. I think you may need to replace the whole turn signal/high beams/cruise control switch....or at least that's what I'm going to try.
IF one of your brake light or turn signal light bulbs are put in incorrectly - IT will backfeed into the computer & KILL the Engine.OR shorted 2 ground.
The turn signal flasher is located 2 inches above where the emergency brake cable attaches to the emergency brake assembly. You lower the fuse panel and then you will need to remove the plastic box just above the fuse panel to see the flasher.
If your brake and turn signal lights are not working on your 1994 Buick Roadmaster, it could be due to a blown fuse, a faulty brake light switch, or a wiring issue. Additionally, check the bulbs themselves, as they may have burned out. Corrosion or loose connections in the wiring harness can also lead to these problems. It's best to start with the simplest solutions, like checking the fuses and bulbs, before looking into more complex electrical issues.