alternator not putting out

[samsonhusky]

Ok just changed Alt. out to a new one because the old one wasn't working now that one isn't working either. I ordered a new wire pigtail for it today if this doesn't fix my trouble what else do I need to look for. The belt is good and tight so I don't think that's my problem. The way i was checking them was pulling the batt cable loose why it's running I've done this in the pass and if the alt is working it keeps running. oh yeah this is on a 85 gt. thanks

[middle school]

man my old lady isnt putting out either, maybe i can trade her in at oreily, should be good for at least a core charge

[yodaddyz82gt]

hey i might need to try that, cause my batt is dead again..

[83t-topp]

try replacing the voltage regulator, worked for me.

[MurPHy]

Check it the right way, get a good DVOM** and see what voltage the alternator is putting out. 13-15V is the normal range. Anything below 13 or above 15 and you have problems.

Also ohm out your charging cables while you're at it.


** I highly recommend Fluke.

http://us.fluke.com/usen/products/categorydmm

[wgt500]

Good test MurPHy. I've found when testing this way, there isn't much doubt when the alt. is bad. Usually they put out less than 11v when they are shot. The last one I tested was around 8v. When the bat is fully charged you will get a steady 12.5v reading. Also most chain parts stores sell a little idiot light charging syst tester that's pretty good. I think they are less than $20. Radio Shack sells an inexpensive volt ohm meter for less than $20.

[86capriASC]

man my old lady isnt putting out either, maybe i can trade her in at oreily, should be good for at least a core charge

This is exaclty what I was thinking after reading the title.LOL

[grtskydog]

Sick minds think alike....buy your alternator dinner first. Maybe get it drunk, but absolutely no roofies!

[samsonhusky]

I have 11.95v before running the car and 12.05v when the car is running I changed the voltage regulator to another used one off of my 86 that has no motor so it might be bad to. I also checked the v on the back of the alt when it was running and it was the same as the batt when it was running. But on the wires what do I have to do to just run new wires from the back of the alt to where they are suppose to be. I did order another pigtail but that's on the alt side i'm not to sure about the wires on the wiring harness side where the pigtail plugs in. If I do run new wires from the back of the alt to what do I hook them up I know the one larger one goes to the solenoid on the batt. side what about the others.

[grtskydog]

If you have 12v at the alternator post (running) also, then it's probably a bad alternator. I wouldn't suspect the wiring unless it just looks bad.

[fred414141]

man my old lady isnt putting out either

yes she is!

j/k

[boss 245]

I had the same issue, I replaced th evoltage reg, went through the wiring and had the alt checked. The alt was good. I switched the battery and it worked fine. My battery was bad, after looking inside one cell was very corroded.

[samsonhusky]

Well I got the alt working now, it was the voltage regulator I change it to a new one {should did new one to start with} after doing this test posted by JACook under Charging System problems thread. This is the test I did if anyone wants to know. Wish I would have did it before buying a new alt. Thanks for all the input.

There are four terminals on the back of the alternator. They are output, field,
stator, and ground. Battery voltage being present at the output terminal is not
enough to get the alternator to charge, since this isn't a "one wire" setup.

First, verify the ground wire. Don't presume the alternator will ground through
the brackets. The engineers who designed it to have a ground wire did this for
a good reason.

With the engine stopped, you should see battery Voltage on the output terminal,
and zero Volts on the stator terminal. with the engine running, you should be
seeing about 14.6 Volts at the output, and about 7.5 Volts at the stator terminal.

If the output only shows battery Voltage with the engine running, the next step
is to measure the field terminal. The field terminal is the one that's closest to
the alternator centerline. If you're seeing 12 Volts there, and there's no output,
the alternator is defective. Period. Normally, you will see a voltage on the field
terminal that's proportional to the amount of output being requested from the
alternator. That is to say, the field Voltage is greater when battery Voltage is
low, and decreases as the system nears the ideal 14.6 Volts. The field Voltage
is supplied by the regulator.

You may have heard the term 'full field' testing. This is a pretty good way to test
the alternator function, but it's also a pretty good way to fry a solid-state regulator.
If you elect to do this test, disconnect the regulator connector. You would then,
with the engine running, connect the alternator field terminal to battery + while
monitoring the alternator output. Only leave it connected long enough to see
if you're getting output, or you can damage the alternator.

If you're not seeing Voltage at the field terminal, we need to figure out why not.
The field terminal is connected to the 'F' terminal on the regulator. Ford regulator
terminals are arranged I-A-S-F with the tabs facing you. On the '83 GT, that
would make the field terminal the one on the bottom. If you see Voltage there,
but not on the field terminal on the alternator, you've got a wiring problem. If
you don't see Voltage on the 'F' terminal, the next test is to see what you have
on the 'A' terminal. The 'A' terminal is the system voltage sense, and is spliced
into the main yellow wire that feeds the electrical system. This terminal should
have battery Voltage on it at all times.

Finally, you need to have the signal to the regulator that tells it to turn on. That
is the 'S' connector, and it is fed from the same circuit that feeds the Duraspark
module when the ignition switch is in the 'run' position. The 'S' terminal should
show no Voltage with the ignition off, and around 8 Volts with the ignition on.
If not, you have a wiring issue between the regulator and Duraspark module.
Otherwise, if the 'A' and 'S' voltages look right, but there's no 'F' Voltage, the
regulator is defective.

The regulator 'I' terminal is for the 'ALT' light, and is not used on cars factory
equipped with an ammeter.
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[85GT/EFI]

check your ground wire thats mounted to the timing cover