alternator question

[markman2]

Hi, my 83 Blazer with 6.2 engine has a short somewhere and I am trying to understand how the alternator works:

it's a 3 wire alternator, one wire for the battery, one for the field (12V) and one for the gauge.

I bought a replacement alternator (Delco) and it turns out that this type usually needs the field wire switched or otherwise the battery will drain. Now on my truck the field wire goes to the starter and from there directly to the battery so naturally the battery drains very quickly.

I am wondering now whether this alternator is not the correct one for my truck, it fits perfectly but I don't understand why the field wire is not switched. Does anyone know how this is supposed to work?

Thanks, Mark

[gmctd]

Terminal #1 ties via the brown wire thru the idiot lite to the Ign Sw - check for 0v with key off.
+12v thru the bulb turns on the field supply source

Terminal #2 ties direct to the battery, as does the large Batt lug bolt - reverse-biased junctions prevent current flow when alternator is stopped

[markman2]

I bought another alternator from another store (Kragen) and that one does not leak. Looks like the other store sold me the wrong alternator.