Voltage Regulator Resistance

[Charger Fan]

Saw a video on You Tube about checking my '73 Dodge voltage regulator using a multimeter. The video indicated a "good regulator will indicate 1.75 ohms on a 20k ohm scale or 1,750 ohms. I suspect mine is bad and when I check it it reads 3.2 M ohms or 3,200,000 ohms?


check mopar voltage regulator resistance - Bing video

 

[Don Frelier]

If you have battery voltage on the ignition terminal and jump the field to ground you should get full field charge from the alternator.
If the the battery voltage doesn't change much then your alternator is bad.
If it does charge then the voltage regulator is bad or not grounded.
I've never had a regulator go bad.

 

[RJRENTON]

The voltage regulator for the isolated field alternator MUST BE GROUNDED thru the mounting bolts. The voltage TO the alternator is supplied thru the blue wires, thru the brushes, the rotating field windings and OUT thru the green wire back to the voltage regulator. The other blue wire to the voltage regulator supplies battery supply and is the reference for the regulator to control.
There is a switching transistor inside the voltage regulator (along with a temperature compensation network and a voltage divider network) that turns the switching transistor on/off to supply a variable voltage (~ 0 - 6 vdc)/current (0 - 5 amps) to the alternator rotating field windings.
Since there are several internal components in a series-parallel network inside the voltage regulator assembly, testing it with a V-O-M on the Ohm's scale is useless, as the transistor must be biased on to test its conductivity...it's a current sinking circuit application (likely it's an NPN transistor), if in doubt as to the voltage regulator integrity, test by substitution. The afore noted method will show the alternator is capable of charging.....it does not test the voltage regulator. This is how the system works......
BOB RENTON