We recently replaced the original alternator on the Yanmar 3GM in our Hunter 34 with a high output version (I think it's a Hatachi). The wires all seemed to match up with the exception of an extra single yellow wire on the back of the alternator. It doesn't appear that we are getting any juice from the alternator but when we took it to an auto parts store for testing they demonstrated that it would generate nearly 15 volts. The yellow wire showed up as a "stator wire (optional)" on the diagram that the auto tester showed for our style of alternator. A voltage test at the alternator shows 12.5 volts before start-up and drops to 12.4 after start-up which I assume represents the drawdown from the starting process. Any ideas on what we're missing?