I just replaced the alternator; but the battery light stays lite on the dash after I shut the engine and take the key out.
Does this indicate that the battery is draining???


Thanks again.

Bob H.

Yes, it is a bad diode. A bad diode will allow current to go in the wrong direction, effectively trying to turn your alternator into a motor. This is why it is hot after you have shut it down.

Bring it back, and tell them you want one that is good this time, not one with a bad diode in it.

There is a short in one ( or more) of the diods in the alternator. You have to replace the complete diodunit (or alternator). Yes, it drains your battery.

First --- What year?

Second, disconnect the little red wire on the back of the alternator. If the light stays on, there's a short. How's the ignition switch? Do you have lots of keys on your key ring?
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.

Hi Warren,
I have 1985 740gle. I just went out to the car and disconnected little red and the battery light went out. Strange thing though-the alternator was blazing hot, even tho' I parked it two hours before. I disconnected the battery for the night- I dunno- fire.
I just bought the alternator-it's rebuilt-at Autozone- a local parts store.
Do alternators run that hot? One of the posts mentioned a bad diode?

Thanks

Bob H.-Boston-88 degrees

hello

Bob, it shouldn't be hot. Take it back and have it checked on their tester.
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Warren Bain - '86 744Ti M46 >290Kmi, '99 V70Glt > 45K mi, '96 965 >100Kmi Wifemobile near Manassas Va.. Check the 700/900 FAQ via the 'features' pull down menu.

unfamiliar with your model is voltage regulator built into alternator?? seems like you are getting some kind of reverse current --would drain batt eventually but i would be concerned further damage may happen--does your ignition switch feel sloppy/loose when you stick you key in and crank motor??