My 99 Explorer had been running fine. Tonight I left my lights on, killed t he battery - which is about a week old from Walmart. Boosted it with anothe r battery I have that happens to be good. Car fired up but the connection n ut with the rubber boot at the top of the alternator started glowing red ho t. Obviously can't run it like that.
Any ideas what's happened? Never encountered this before.
Thanks.
Hello, and if you're talking about the output terminal (not the field coil terminal), then perhaps one or more of the internal alternator diodes is/are shorted. Motor vehicle alternators are three-phase AC and supply that to a full-wave, six-diode rectifier bridge assembly. Those diodes can be internal or external to the alternator but most of the time they're internal. A shorted diode or two could allow for the flow of battery current to ground (car frame). Sincerely,
Your alternator is shorted to ground internally. Either because it got a brief reverse polarity spike or just because it failed from age. You may be able to get the diodes in the regulator replaced or you may have to swap out the whole thing.
--scott
Alternators. The weakest link in the vehicular electrical chain.
So I can take out my fusible link then?
No, the alternator does that for you.
--scott
AMuzi wrote: " So I can take out my fusible link then?
-- "
No, wiseguy. Alternators are the most likely underhood component to go bad in an automotive electrical system. That's all I was saying.
Back in college went through three new batteries in my '81 Buick. Replaced the alternator after that third one and never bought a battery for that car again.
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