Yeah, that is a fine place to check the voltage. According to my diagram, one wire should be black and yellow, and the other wire should be black and green. You want to check for voltage on the back and yellow wire.
As for resyncing the EWS module. Yes, an Indy can do it. Or, you can get INPA setup on a laptop without much investment of time or money. The USB diagnostic cable to connect to the car can be had cheaply on eBay , or there are more expensive ones ($80 or so). There are whole forums devoted to BMW diagnostics with INPA and GT1/DIS.