voltage regulator

They are generally part of the alternator, is that what you found with yours? Were you able to replace it separately or is it integrated into the alternator?

It is separate, the regulator is a silver box like bolted up just behind where the hood lifts up. If you are looking at the oil dipstick mine is above that (bolted to the top). It has wires that connect to it in a triangle type shape (but only 2 wires go in). Hope that helps

The repair manual that I have, saids that it is located in the SECM -aka- computer.

i have a 91 van the computer regulats the voltage in it but im not sure its the same in a 1990

The voltage Regulator in a 1990 Dodge Ram B 250 5.9 liter cargo van is inside the ECM unit.