Jim Lane

In the future,
Not such a good idea,
Especially in newer vehicles, that could destroy the alternator and ecm if you had one.

Our charging systems are really basic and can be diagnosed and repaired with only a few tools and a little bit of knowledge.

The good news is you did narrow it down to your charging system

whosdunit

Ha,,Ha,,Ha ,,Ha I love those little guys J Martin,,,That's the reason I ck., here!!!,so what if I pull my fuses,one at a time won't that at least tell me which circuit it may be on ??

Thanks ,Jim & J.m.

j_martin

I'm with Jim on this. It's in your charging circuit somewhere. If it were something else, it wouldn't have gone away when you disconnected yer battery.

Jim, check me on this. Likely either an internal connector in the battery is intermittent, or a diode in the alternator is intermittent.

If you have another battery to sub in, try it. It can be a car battery for this test. If it still jumps, take the alternator off and have it load tested.
Luckily this one comes off pretty easy, unlike a V6 Caravan.

whosdunit

OK,gang,,, run by "o' reily's" cked., alt., at idle ( w/ amp needle jumping) tester read diodes good !!!but showed 15.9 volts*** what to do , what to do ??? new alt 102.00,,can I fix this one at home ( I'm ..a liiiitttle short just now. "Jim ",. all stock stuff here.

whosdunit.

j_martin

If the amp needle was jumping on the tester, the alternator is bad. (diode or brushes.)

You could pull the brushes, and if they're short, replace just them. You can also test the brushes by putting an ohmmeter between the field terminals and sloooowwwly rotating the armature. watching for big jumps.

The voltage is externally regulated. Whatever voltage they got is what their machine told it to give. 15.9 would be good, unless they were expecting more.

You can't check the individual diodes unless you disassemble the alternator. One open diode won't show on an external test. All it checks is reverse leakage.