Brake lite short?

[BiXLL]

I have a 93 sx vert. My driver side rear, outside brake lite does not work when the headlites are on. It works fine when headlites are off, but when brake is applied with heads on, both the tail lite and brake lite go completly out on that bulb. I have tried changing the bulb with same results. Any ideas besides I have a short "somewhere"?

[240_newb93]

might just be the wiring in the electrical harness/tail light housing (for lack of better words) where the rear lights are located. I'm having a similar problem with my '93.