brake light on left side doesnt work when headlights or parking lights are on.

I'm having the same problem. Went to the auto parts store last anight and they said it was a short since it was only on one side. Having mechanic look at it will give update. told to look at the Grounding wire for the assmebly on that side.

i had the same problem it was the ground on the harness

I also have a 1992 Nissan sentra. When my headlights are on then you apply the brakes both sides of the brakes lights go out but the the center light will brighten up. I heard possibity it could be a ground wire loose. Taking to a mecanic today.