Testing Generator Field Coils

[Joe Flanagan]

I just read the procedure for this in my manual. One kind of test is easy. You connect one end of a test light to the field terminal and the other to the generator bracket. The other is not so easy. You attach one end of the test light to the leads from the field coils and the other to the generator bracket. Can you do this with the generator in the car or do you have to have it disassembled? Also, I assume if you do this second test and the light goes on, you have a grounded condition, correct? Manual also says to push something called the "ground shoe" out of the frame, which is a complete mystery to me. 

Has anyone done this?

 

Oh, and the reason I ask is because my generator acts like a tachometer. It's done this since I installed it and I've never been able to figure it out. It does it with a new, fully charged battery and even if the engine has been running a long time. I have the generator grounded properly and also the voltage regulator. Voltage regulator is new and the generator was tested early in the rebuild and passed. It was tested WITH the regulator.

[Don Coatney]

This might or might not help

 

[Joe Flanagan]

Thanks for posting that, Don. I'm going to perform the tests from the manual that I know I can do and then see where that leads me.

[DCurrent]

This might or might not help

 

Towards the end of that clip he disconnects the negative wire to the F terminal and it motors faster. I can't determine where that wire came from. The case is wired to the positive side of the battery. Then the negative is wired to the Armature (A) stud. Is the F stud (Field terminal) also wired to the Positive side of the battery? He calls it a ground, but he had it wired as a negative ground I guess.    

[Don Jordan]

Good thread - thank you

[Joe Flanagan]

Today I performed one of the tests described in the manual. I attached one lead of a test lamp to the field terminal of the generator and the other to the generator bracket. The light did not go on, so by that test, at least, I don't have a grounding problem in my generator. But there could be a problem with the coil leads or the coils themselves. Would I need a growler to perform any further testing? I could go straight to testing the voltage regulator but I'd like to eliminate the generator if I could.