Began experiencing other lighting problems after changing the brake light in my 2001 Honda Civic EX sedan. With headlights on, all works fine when I hit the brakes. With headlights off, multiple lights come on including interior lights (dash and gear shifter), brake, and parking; additionally, there is a beeping sound (the one that alerts you that your headlights are on) when you hit the brake. Any ideas of what might be happening? Theorectically, only the brake lights should be affected. Note - changed bulb back to the one replaced and am still experiencing the same problems.

I would suggest checking the wiring for the brake lights. Look for a spot where the wiring is pinched or heavily rubbed. It sounds like the power is being back fed through the parking light wiring in the same harness. If that does not fix it, try replacing both or all brake light bulbs, as you might have a bad filament hanging inside the bulb.