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Discussion Starter · #1 ·
Using a meter at the alternator sometimes my daughters alternator will output normally and sometimes it will not output at all. Battery light on dash is illuminated when it's not charging but then it will start charging on it's own. All testing was done at idle and you can hear the idle speed drop when it kicks in and then it will work fine for several days. I've bypassed the ground node BS, replaced main ground cable off the battery, the battery is new. Alternator tests fine off the vehicle.

Best I can guess is that there is something that tells the alternator to output some juice and that is likely the problem but I don't know how to track that down.

Any ideas?
 

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I have had trouble with the connectors to the alternator. One of them has 3 contacts, the other one has a single contact. That is the wire that actually tells the alternator to charge. I have pulled the connector off, and cleaned it up with emery paper. That solved the problem I had. This single wire gets its feed from the other connector - the one having three contacts to it.
 

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When the alternator is being spun by the serpentine belt, it's producing its voltage (if it's working). It doesn't have any manner of internal "swtich" that is computer controlled. So if you're checking votage at the alternator and its output is intermittent, then I'm just going to guess that it's on its way to failure. Where - exactly - are you putting your meter probes?
 

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Discussion Starter · #5 ·
I have had trouble with the connectors to the alternator. One of them has 3 contacts, the other one has a single contact. That is the wire that actually tells the alternator to charge. I have pulled the connector off, and cleaned it up with emery paper. That solved the problem I had. This single wire gets its feed from the other connector - the one having three contacts to it.
This is the most logical response so far, so I will look into it. It puts out 13.6-14.5 when it does decide to call for voltage so it's not the alternator itself. It has to be something in the wiring. Thanks
 

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Discussion Starter · #6 ·
When the alternator is being spun by the serpentine belt, it's producing its voltage (if it's working). It doesn't have any manner of internal "swtich" that is computer controlled. So if you're checking votage at the alternator and its output is intermittent, then I'm just going to guess that it's on its way to failure. Where - exactly - are you putting your meter probes?
the output post on the alternator and ground to chassis, only place you can check it at the alternator that I am aware of. There has to be some mechanism that is causing the problem. I just haven't figured it out yet.
 

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On the side of the alternator (opposite the side with the pulley) there is a place where the brushes bolt into the alternator case. I I recall correctly one of these tiny bolts (they are a torx head bolt) has a place where you can short that bolt to ground, which will make the alternator charge at full strength. The engine has to be running of course. Be careful which bolt you ground, as the other bolt has 12 volts on it anytime the ignition is on. Or should have anyway.
With one of my alternators that was intermittent, the single wire connector came apart as I was pulling it out. I used an ordinary female spare terminal from my electronics stuff and soldered that onto the end of the wire. That fit snugly on the pin on the alternator, and fixed the intermittent-ness.
 

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How many likes are on this alternator?
I am thinking that you have worn out alternator brushes/
 

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What exactly is this supposed to do? The whole alternators is already grounded to the chassis simply by being attached to the car.
I guess gives it a better ground? Someone from the forum told me they had to do this to their car since it had intermittent charging.
 

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Discussion Starter · #12 ·
I guess gives it a better ground? Someone from the forum told me they had to do this to their car since it had intermittent charging.
I ordered a new alternator, this one is original and has some rust in it. Hopefully that solves the problems. I checked the wiring and all looks fine and still had electrostatic grease on the fittings. I replaced that ground off the battery and ground node already. I don't think it's a ground problem. I suspect the internal regulator is going bad or the brushes possibly loose. For $150 I'll take my chances on a new one fixing the problem.
 

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Even though they were still working okay, I have replaced an alternator or two (on one of my 5 escorts) simply because when I had it off the car, I took out the brushes - and saw that besides the brushes being much worn down, that the brass slip-rings were also well worn down below the level of the plastic hub of the rotor.
After I undo the two bolts that hold the alternator in place on the engine accessory bracket, I use a large screwdriver and hammer, to hit the case of the alternator next to that threaded insert. This moves the insert a couple of thousandths out, so the alternator flops freely in the brack. Makes it much easier to get a used alternator back into place.
 

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Discussion Starter · #14 ·
I replaced the alternator, plugs, cleaned idle air control, and throttle body. Not that it's all related but everything seems to be working well now. Thanks for the suggestions. Seems like the charging problem was internal to the alternator.
 
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