Voltage Regulator Identification

Voltage Regulator History

Chrysler voltage regulators used on alternator type charging systems evolved from the generator days. Regulators on generators usually used three separate coils, one for voltage regulation, one for current regulation, and one as a cutout to disconnect the generator from the battery when the engine was not running. When generators were replaced by alternators the voltage regulators became more simplified and only required a coil to control the field circuit. Chrysler used the mechanical type of voltage regulator through 1969 and replaced it with the electronic type for the 1970 model year. Voltage regulators control the field circuit by rapidly switching on & off. When more output is needed from the alternator, the field circuit is turned on longer and when less output is needed, the circuit is off longer. The mechanical type of regulator was known as a "B" circuit in which the field circuit was controlled by the amount of current sent to the alternator brush terminal. The electronic type of voltage regulators are an "A" circuit type. In this type of circuit, full battery voltage is sent to one field terminal on the alternator from the ignition switch. The second field terminal of the alternator goes to the voltage regulator which now controls the circuit by switching the ground on and off.

Voltage Regulator Identification

It is pretty easy to identify correct original Chrysler voltage regulators. The 1960-1969 mechanical type of voltage regulator had a black metal cover that extended down over the base mounting ears. The mounting bolts actually go through the black cover and the base. On aftermarket voltage regulators the cover will crimp onto the side of the base and the mounting bolts go through the base only showing the silver metal base. The lettering on 1960-1967 voltage regulators is red and the 1968 & 1969 model years had yellow lettering. The electronic voltage regulators used from 1970 on can be identified by looking at the front of the voltage regulator. A correct voltage regulator has a stair-stepped ledge by the lettering. On an aftermarket voltage regulator the ledge is straight across. Mopar Performance makes the correct type pf voltage regulator, however the lettering is incorrect for the 1970's cars. The lettering on a 1970 & 1971 Mopar is white and the 1972 and newer is yellow. The new Mopar Performance voltage regulators also use a four digit date code, whereas the early 70's all used a three digit date code. The first two digits of this date code is the week and the third is for the year. A "340" date code would be the 34th week of 1970, which is the last week of August.

1960-1969 Style Voltage Regulator	1970- Style Voltage Regulator