I hope someone here will be able to give me a quick diagnosis.

This is a 97 Sentra.

If the headlights are on, the left brake light doesn't work. The tail lights, right brake, center brake, and turn signal lights all work all of the time, and if the headlights are off everything works.

Suggestions?

Thanks!

 

Check your ground connection at the light fixture, its probably loose or dirty

 

check the bulb to see if it is blown that would be the first place i check first before messing with anything else.