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99 DOHC Taurus, the alternator does not charge the battery, but the little warning light does not come on either. I need to crawl under and check the wires, but was wondering if anyone has any thoughts? My manual says to check the wires, battery connections and fuses. I tried to check the 175 amp super fuse tonight with an meter, but I think I need to disconnect one side to check it. Both sides registered 12 volts, but one side is from the battery and the other is from the alternator, and they may both have voltage all the time. Anyone know anything about the super fuse?
 

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My car did this exact thing but there are several causes. Mine happened to be the 30 amp field coil fuse in the under hood fuse box. It's the box that has that super fuse on the side of it. Open it up and look inside. There will be a green 30 amp fuse for the field coil of the alternator. It popped on mine and that caused it to not charge but also to not throw a light. I would say to have the alternator tested, but removing it on the DOHC is a ***** to say the least. If that fuse isn't busted, then you'll be removing it anyhow because the alternator is bad.

 

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thanks for the tip. I did check this fuse and it is fine. You are right, removing the alternator is a real treat. I took it off once to replace a head, so I know it is hard to get at and as I recall, you have to take several other things off to get it out of there.
 

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Good idea on checking the field fuse.

Does the low battery light come on during the "function" test at KOEO????

Seeing as how the alternator has been removed in the past, maybe re-check it's electrical connections.

Is the alternator not outputting anything at all, or is it's output just low????.
 

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the field fuse and the super fuse are fine, the low battery light does come on when you turn the key to on, so I know it isn't burned out. There doesn't appear to be any output from the alternator. The electrical connections are my next step. I was waiting until I had all the easy test done before put the car on ramps and crawling under it. It just seems strange that the idiot light does not come on when it is clearly not charging the battery.
 

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What is the voltage when there is a large electrical load and the engine is running at or near 1500 rpm? Should be better than 13.5v. If not hen the alternator needs changed.
 

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OK good feedback, so the fuses & the low battery light are ok.
So I gotta ask this, why do you say the alternator is clearly not charging????
 

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Okay, still messing around with this. I had Advance run their test and they said that there was no output from the alternator. I have check the connections on the alternator and they seem good. I pulled the field fuse with the car running and the idiot light came on, when I replaced it the light went off and I could hear the alternator slow the engine slightly, so it is doing something, but is not charging the battery. Is it possible that bad brushes could be doing this?
 

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Was the alternator output test that Advance did, with all of the vehicles components in place, with their portable electrical system tester????

Where all did they measure the alternators output from???? Was it just across the battery posts, or did they also measure output AT the alternator????
If it was measured AT the alternator, then I'd pull the alternator & have it bench tested before replacement, just in case it's a wiring, or connector problem.

I suppose it could be a slipring brush problem.

Did they also load test the battery????

Will be interesting to hear what you find.
 

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they did the test at the battery across the battery posts, with the portable system tester. They did not do the load test, I am assuming, because the alternator indicated no output. I probably just need to pull the unit, but I know what a job it is to do it.
 

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If you have a multimeter, you could do an output test at the alternators B+ connection, before you go to the trouble to pull it.
 

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Same problem here on my 1999 Taurus. I replaced the battery and the alternator. The car would only start with a jump, then the alternator voltage at the battery was only 12v instead of the 13.5 to 14 it should be.
SOLUTION: There are two cables on the negative battery terminal. One goes to the motor (block) and the other goes to the car body (fender). The one going to the fender was broken inside of the insulation (couldn't see it), and read good with a meter (continuity). Replaced that black wire and everything works as it should.
 

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Same problem here on my 1999 Taurus. I replaced the battery and the alternator. The car would only start with a jump, then the alternator voltage at the battery was only 12v instead of the 13.5 to 14 it should be.
SOLUTION: There are two cables on the negative battery terminal. One goes to the motor (block) and the other goes to the car body (fender). The one going to the fender was broken inside of the insulation (couldn't see it), and read good with a meter (continuity). Replaced that black wire and everything works as it should.
There are 2 parallel battery negative to body grounds. Either one should be removed and it still start. Other issue of course.
One to the fender. and one from the engine block to the firewall. Best check the one to the firewall. Ford bolts grounds over paint and depend on the bolt which rusts. You need both grounds being GOOD.
-chart-
 

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Good replies But this thread is 10 years old!!!!
 
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