My 96 caravan 3.0 has a intermitent charging problem. What it will do is overcharge forless than a second (I can see this in the headlights at night)and then it will go back to normal but the idiot light will come on, it seems to do it just after you have pulled out from a stop before you get into second gear. Sometimes it will not do it all day othertimes it will be more frequent I have changed the alternator, battery and the ECU (used)
THANKS

 

probably the wiring btw the PCM and alternator is bad.

 

Check the charger regulator! The alternator generate more than 14 V there is a regulator that regulate the power! some time it comes in the alternator or separate. I dont know where but try to find out !

Good luck!