[quote name="tillithz"]could be something other then a ground you "think" is a ground. how did you determine it was a ground?[/quote]
I tapped into the black wire of the pioneer harness, which I know connects to the brown-colored ground wire of my scion tC harness.
if what i connected to wasn't ground, then in the connection status menu of the D1, shouldn't the parking break status not say "ok" at all, even when the car is stationary?