Alternator Test

[CruisinGA]

Is there a way to test alternator function independent of the regulator?

I know of the three wires connected to the alternator, B terminal is essentially directly connected to the battery, and of the other two smaller wires one is just a ground (grounds at the regulator.) And the third just "goes into the regulator."

What I don't know is what the third wire does, I want to manipulate it so that the alternator thinks that the regulator wants it to charge.

Does that mean +12v? Or what?


I'm trying to root out a charging problem and have narrowed it down to either the alternator or the regulator malfunctioning.

 

[jwest]

I'm guessing you're reading under 13-15 volts at 2k rpm's.

I don't know if you have the following on your alternator,
but grounding the 'F' or Field terminal bypasses the regulator.

If you're still reading low at 2k rpms after grounding field, then the problems in your alt.

.

 

[desertdude]

some good info here http://www.madelectrical.com/electricaltech/howitworks.shtml

scroll down the page for more details

 

[Dan_J-spec_fj62]

gee wizz here but did you check your fuses??? i had charging issus that drove me nuts untill i checked the fuses.... had one blown and the alt would not charge dookie


good luck

dan

 

[CruisinGA]

yes I've checked fuses, yes i'm reading low voltage (12.5) and the ammeter is indicating a discharge.

I have the field terminal grounded (on my truck its that way factory)

There is another wire that plugs into the alt that I need to know how to manipulate-I think it gives the alternator voltage to tell it to charge but not sure.

 

[offcamber40]

I know that some auto parts stores will bench test an alternator for free if you feel its a problem with the unit versus a wiring/harness problem. Pep Boys, Checkers and advanced auto parts all offer this free service.. it might help you track down other problems if you find out the alternator get a clean bill of health.

Mike

 

[CruisinGA]

I don't trust those services-I've had them lie to me before.

My charging system is far from stock, ie custom harness, fully electronic regulator, different year alternator. I need to get it to work on my truck, not in a bench.

Thanks for the suggestion though.