1997 Mitsubishi Galant break lights

The most lkely cause is a faulty brake light switch. Its located above the brake pedal and are fairly easy to replace. To test you need to check the wires at the plug, one wire will be positive all the time and the other wire will be positive when the brake pedal is pressed. If you cant get a wire to light the test light when pressing the pedal then you know for sure. Hope this helps