I believe that the ammeter in my '21 Touring is bad. The needle only fluctuates, actually I would say vibrates. I would like to know if my generator is charging. Besides trying another gauge, which I don't have, how can I check it?
I removed the cover on my cutout and looked inside. There are no points like I expected, only what looks like a diode. Obviously a replacement?
take a look at the yellow wire that goes to the cutout. That goes to the battery. Placing a multimeter on that connection and other lead to a good ground, should show about 6.3 volts. Start the car and rev it up a bit. Recheck that same connection. It should show a higher voltage than previously measured, meaning the cutout is passing current from the generator to the battery. Now you know it is charging (or not). FunProjects makes a very nice accurate and stable ammeter that can be bought directly from them or from Lang's or others. And yes, if your cutout doesn't have a coil and points in it, it is a replacement. FunProjects also makes a Voltage Regulator which looks just like a cutout but will save your battery by only sending voltage/current that the battery requires as opposed to a cutout or diode/cutout which simply slams the battery regardless of its need. Modern driving at higher speeds for longer duration's than originally done tend to really tax the battery and the voltage regulator is a really super addition to the electrical system. Your battery will thank you!
You could try adjusting the third brush to see if the ammeter responds to it, this would could determine if the meter is good or bad.
that assumes that the generator is functioning in order to test the ammeter, and there is a question as to whether or not it is charging. Easiest test of ammeter itself, is to simply turn on the lights while the car is "off" and see if a 10A discharge is recorded on the ammeter.
I took the generator off. I removed the end cap and tightened the third brush nut to where the third brush holder would just move, but stay where I moved it. I turned the brush holder so the armature just started to turn with 6v connected to the generator. After putting the generator back on I tried moving the third brush. No luck. Still no charge. What now?
The manuals say you need to find "neutral" first by hooking up to a battery (with the 3rd brush removed) and rotating the brush housing until the armature doesn't turn as a motor. Then tighten the four screws to secure the brush housing. Next you install the third brush and install the generator on the engine. With the engine running and the headlights on .. adjust the third brush to get a reading of around zero on the Ammeter. I dunno ... I'll be doing the very same thing in a few days. :-)