I wired in a manual switch to bypass the parking brake on my 4100.  It worked fine for a few months and then stopped working.  I've verified that I have 12V going into the light green wire , but Android Auto will still not work.  

The odd thing is that without the light green wire connected to anything, I have 3V on that wire.  

Any suggestions?

connect it to ground

OMG, parking brake is not supposed to be fed with any voltage.  It's supposed to be connected to the actual parking brake ground contact as per the manual.

Thats a first.