Going crazy with new Duster and over voltage issue.

HOW THESE WORK The 70/ later VR controls the "amount of ground" that the field sees. There are two field wires to the alternator, one is switched 12V from the key, and the green wire returns to the VR, which grounds the green "more and more" as more charge is called for.

Pull the connector, inspect the connector and VR pins for corrosion, and push it in/ out several times to "feel" for tightness and to 'scrub" the terminals clean.

Another thing you can do in relation to the above tests, is to jumper a nice big say, no16 or 14 alligator clip lead from the battery (or the starter relay "big stud") direct to the "key" side terminal of the ballast. Clip it under the connector on the ballast and leave everything connected. See if your charge voltage goes down to normal, about 13.5--14.2

ALSO VR voltage is TEMPERATURE SENSITIVE so warm up the engine. If you get a service manual, there is a temp vs voltage chart somewhere there in section 8 of the charging system

"Common causes" and can be a combination: Voltage drop at ANY terminal in the path between battery and VR: From starter relay "big stud"----fuse link---through bulkhead connector on big RED ammeter wire--to and through ammeter---out big BLACK ammeter wire--to WELDED SPLICE (in black wire near cluster) ---power feed to IGNITION SWITCH connector---through switch and back out on IGN1 (usually dark blue) and through SWITCH CONNECTOR---back out through bulkhead and to BALLAST RESISTOR