[E60orBust]

I'm doing a hardwiring project in my E92 that is not a GPS or radar detector.

I have a T-tap to the constant power in the overhead console (which I can agree with anyone else who has removed it that doing so is a major PITA...) and another cable connected to the ground bolt. The switch I'm using lights when on, so I know it is getting power, but the device doesnt power on and I suspect it is because it needs an actual ground (negative) cable instead of just a grounding bolt. I've installed the same thing in my E46 and the ground color was brown in that one (e46 wiki) so is it safe to say that the brown wire in the same bundle with the constant 12V is the negative/ground ?

I'm not trying to T-tap two power wires and send my $400 gadget to eletronic heaven.