fuse, swich, cut wire or the flasher could be out. iwould put my money on the flasher.
Possible ground issue at the taillights.
Bad ground on the brake lite circuit.
Not sure what Kind of car this is, but usually if the blinkers run fast it's because you have a bulb burnt out. I'd check your tailights first.
Nonfunctional Brake LightsOne possible cause of this issue is that the brake light switch is not adjusted properly, or the switch could be defective.
Hardness in the brake pedal can because by low brake fluid. Air in the brake lines can also cause the pedal to push hard.
On a 1999 GEO Tracker, a bad fuse can cause the headlights and dash lights to blink. A bad voltage regulator or alternator can also cause lights to blink and flicker.
Try Changing the Brake Hose. They Rot On The Inside And Restrict The Flow Of Brake Fluid Back To The Master Cylinder. GOOD LUCK
Most likely a fuse.
First, check all fuses. Then see if you are getting power to the bulbs. Then the next possibility would be the turn signal switch.
Press the parking brake down one click. Unfortunately, this will probably cause your brake warning light to come on.
Is your headlight switch and blinker switch the same? If so, this is called the combination switch. Sounds like it is bad and needs to be replaced. Not uncommon for these to break.
You should consult the owner's manual, as this appears to be a fuse/electrical issue. You might also consider removing your foot from the brake pedal when driving at night. Happy braking!