Dodge Repair: 1990 Dodge caravan overcharging, dodge caravan, conectors

Question
My 1990 Caravan is over charging.  It has over 500,000 kms on it and I've slowly been changing things as they are needed.  I've replaced the computer (it blew) and for a few days it worked fine.  Unfortunately it's starting to over charge again.  It's charging at over 18 volts.  I've been told that the voltage regulator is in the computer not on the alternator, is this true?  If it is what else could the problem be?

I'm stumped.

Thanx

Answer
Yes the regulator is in the computer, you may want to trace the feild wires back to the computor and the ground, as the car has aged the conectors and wires go bad.  An over charge problem can happen only if the alternator goes to full feild. which is a grounding problem.

Steve