besides all the other suggestions about checking the wires....are your alternator brushes worn...do you need a new brush set?? if the brush set has less than 1/4 inch sticking out of the holder they are worn out.

Obviously this car is not charging the battery.

Inspect all wiring around the alternator. There's a ground wire at the bottom rear of it- it's blue, has an 8mm mounting nut, and usually a red part ID tag on it. Essential to the operation of the alternator. I recently had to fix one on a 1988 wagon where the belts broke- all the wires including the ground were attacked by the shredded belts.

I repaired the small red wire and the ground, both broken. The large red wire and small oil light wire were bare- I wrapped them with tape and replaced the sleeving over the whole harness.

Good luck with yours.
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Rob Bareiss, New London CT ::: Roterande Fläkt Och Drivremmar!

First, check your battery cables. Are both terminals clean and making full contact with the posts?

Check the alternator drive belt. Is the belt loose or worn, indicated by a shiny surface on underside of the belt?

How about the wires at the back of the alternator? Should be three wires; a positive and a negative, plus a black (?) wire that is part of the battery "idiot light" circuit and integral to charging. Loose, corroded or shorting wires will result in a no-charge situation.

System voltage with a fully charged battery and the engine idling should be between 13.8-14.6 volts. If voltage is lower, the brushes are suspect. If system voltage increases with engine RPM, the regulator is shot. To isolate the regulator, measure voltage at the D+ and B+ terminals at the alternator. If there is a difference of more than one volt, the diodes in the regulator are faulty.

It sounds like the alternator is bad or a snapped wire has disconnected it from the system. The wire that runs under the engine to the alternator is often the culprit. Do you have a voltmeter? If so, you should get 14 or so volts across the battery terminals when running, but only 12.7 when not running.
Good luck,
Tom