[cgtech]

I think you were seeing your ground through the light bulb, even tho the Br wire is B+ from keyswitch to bulb.

As for as "green & black", maybe low oil indicator lamp? Does your low oil indicator lamp work? The sensor connection is on the back of the block, between the primary & secondary clutches. The circuit can be tested by disconnecting the sensor wire at the engine & grounding it to the block (that's what happens when the low oil level sensor float is activated, B- is supplied to the circuit).