High mounted brake light stays on

[andy05]

This is a weird one. High mounted brake light has been working fine, but tonight on the way home I noticed it was on all the time. When I braked, it became brighter. But when I turn off my headlights it works as usual. Weird huh?

[1991_Vn2nV]

But it would only have a single filament globe in it? How could it have two stages of brightness?

Thats weird man... Have you been fiddling with it recently?

[HATER VP]

Because it would be getting more power to it. Are the other brake lights on?
It seems like it wired up to the tail/stop wires but couldnt be with out the dual fillament globe