Alternator wiring question. Update: Problem fixed.

[clbanman]

91 Golf 1.6 NA.  Yesterday on the way to the in-laws, the fuel gauge and coolant temp gauges started dropping abnormally fast.  No battery light at any point.  Needless to say by the time we got there the battery was dead.  Pulled the alternator off and took it to Crappy Tire for testing - they said it was no good.   Bought a rebuild and installed it, still no charge.  What signal should I get on the wire to the D+ terminal - actual battery voltage?  Mine has a wire on the W terminal as well but I have no tach so am I correct in assuming that it serves no useful function?  If the problem is in either the alternator warning light or voltage stabilizer, could I bypass this with a wire from the dash panel to the D+ just to get the thing functional while I figure out what failed or would this cause other problems?

[clbanman]

I still don't know the answers to my questions, but the problem ended up being the terminal at the starter for the wire from the alternator to the starter being so corroded that it was actually broken off and just sitting on top of the terminal on the starter solenoid.   Don't know if I replaced the alternator for nothing, but I have a bright new shiny one now.