charging system?

hello,,,,I have a 96 caravan 3.0...took the alt to autozone and it tested good,,,,but it wont charge when its on the van....I tested the wires on it,,,,its a denso alt. it has 4 wires,,1 stator,one ground,and to green field wires...with the van running it had battery voltage from the stator(large red wire),and the field wires j2 and r3,,,one had voltage,j2 i think,,and the other had very slight votage,,, .013v...my question here is,,are both the field wires supposed to have voltage??,,if not what do they go to???
thanks

Without a full-color picture of your alternator, complete with all wires attached, I won't even BEGIN to GUESS what the problem is. However, I will say this...

The amount of DC current produced by the alternator is controlled by the Electronic Voltage Regulator (EVR). The EVR circuitry is contained within the Power Control Module (PCM) and, among other things, the EVR monitors battery temperature and system line voltage to recharge the battery (in cold weather, voltage is increased, in warm weather voltage is reduced).

If I were you, I would take your Caravan to a dealer and have them check out the alternator wiring (simple, quick and cheap to do) and also have them check to make sure that the EVR is doing its job. The most you'll probably spend is $50 for the inspection. Otherwise, I think you are BEGGING for a July 4th fireworks display under the hood.