Brake light goes out

[Stoney]

When my headlights are on my drivers side brake light goes out when I press the pedal.
If just the parking lights are on both brakelights work.
With no lights turned on both brakelights work.
Anybody got any ideas what to check?

[busterwivell]

When weird things like that happen, I start checking grounds.

[tronitec]

Hi Stoney
It's almost certainly a ground fault. Check the negative terminals. Test it with an extra cable running from ground to the lamp.

regards
Thomas