This schematic is the double-contact voltage regulator wiring diagram for the 1958 Chevrolet Passenger Car, Truck, and Corvette. Some electrical components shown here are like: cutout relay, voltage regulator, generator, ammeter, battery, shunt winding, series winding, resistances, etc. A voltage regulator with two sets of contacts in the voltage regulator unit is used on a special option models equipped with the 45 amp. generator. A label on the cover of this regulator identifies it from the standard regulator which is similar to that used on past models. The diagnosis and adjustment procedures are revised with the new unit, and the serviceman must never ground the field terminal of the regulator, or the contacts may be burned out. Basically, the voltage section of the regulator is equipped with two sets of contact points where one set was used previously. One set, the lower, is used to cut in and out a resistor in the field circuit for voltage control at low rpm, the same as on previous models. At high rpm, with the high output generator, this resistance is insufficient to control the voltage, and generator voltage begins to climb. As the generator voltage climbs, the increased magnetic attraction in the voltage unit brings into play the upper set of contacts, which are shunting contacts and actually short across the field to reduce field current flow. The image shows point A on the regulator, which is connected to “A” terminal of generator. Point F on the regulator, is connected to the “F” terminal of the generator. Closing the upper points brings “A” and “F” together, shorting out the generator fields, and shutting off any current flow in the field circuit. This in turn reduces generator output, and as these upper or shunt contacts vibrate, they effectively control the voltage output of the generator at high rpm.