tlorber,

If you search using "diode" you will find your answer. I don't think your alternator would charge if you had #1 and #2 reversed.

#1 is the excite wire and should go to a source which is switched with the key...#2 is your sense wire that looks at system voltage. You might have this attached to the main power lug??

A bad diode will allow the alternator to charge, but will backfeed system voltage when the rig is shut off.

It usually takes a professional auto electric shop to diagnose the alternator.

Stuart