Most likely a broken wire somewhere, it should be a dual filament bulb witch means that the tail lights would still work. could also be a bad ground or flasher
It needs checked out but both the hazard and brake lights go through the turn signal switch.
if you mean: "why do hazard lights flash when brakes are on", then the answer is because vehicles are equipped with a hazard light relay that supercedes the brake lights. This way, slow moving vehicles can operate under hazard lighting.
The problem points to the directional/lights and hazard switch. The brake light wiring is part of that circuit.You can buy the switch after market it is about $70.00.
Your problem very well could be the hazard switch. i have a 1994 honda civic too i found whenever i disconnected the hazard switch from the wiring harness my turn signals brake lights and of course hazards do not work. Maybe replace the hazard switch..
Check the brake switch at the pedal.
turn signal switch needs replaced!
The hazard switch and the turn signal and brake lights are all incorparated, chances are the 3-1 switch is broke internally check all fuses
94 mercury grand marque dashboard, hazard, and tail lights do not work?
Check the brake light fuse. If you have 12 volts at the brake light switch I would suspect the signal light switch is at fault.
If you just barely touch the brake pedal the brake lights will come on but the brakes will for all intent and purpose not be applied.
you need to get a bigger fuse
Have an electrician check the wiring that goes to the brake lights in the trunk of the car.