Why is it not charging????

You need to put the wire from the alternator back onto the alternator. To measure voltage drop across the wire it has to be connected. It won't read 14v at idle. Charging is controlled by the pcm. If the truck was a dual alternator truck and one alternator is removed the PCM can pick the wrong alternator to charge from. The batteries have to have enough power to supply voltage to the field inside the alternator for it to start charging. If you put a new alternator on a junk battery it won't charge a junk battery.
 
Batteries are brand new and load test fine.

PSDPlayer said:
Voltage drop from the back of the alternator to the passenger side battery. But the red on the alternator and the black on the battery. It should read less than .5 volts. Since a voltmeter measures voltage differential you are looking at the difference of voltage at the alternator and voltage at the battery.
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I'm a little confused on the voltage drop measure that you are describing.
From your descriptrion i should connect the red meter lead goes to the alternator and the black meter lead goes to the passenger side negative terminal (or positive terminal?) on the battery.

Thanks for all the help. :thankyou2:
 
wewille said:
where in southeast wisconsin are you? I may be able to help ya out or get ya to somebody. Did you do the voltage drop like psdplayer said?
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I'm located in Muskego.
I did not understand the voltage drop that he was describing, but I’ll give it another shot tonight after work.
 
PSDPlayer said:
If the truck was a dual alternator truck and one alternator is removed the PCM can pick the wrong alternator to charge from. The batteries have to have enough power to supply voltage to the field inside the alternator for it to start charging. If you put a new alternator on a junk battery it won't charge a junk battery.
Click to expand...

The truck is a single alternator truck
 
midnight2004 said:
Batteries are brand new and load test fine.




I'm a little confused on the voltage drop measure that you are describing.
From your descriptrion i should connect the red meter lead goes to the alternator and the black meter lead goes to the passenger side negative terminal (or positive terminal?) on the battery.

Thanks for all the help. :thankyou2:
Click to expand...


Positive terminal, you are checking that wire for a voltage drop. Yea it sounds a little wierd to do, but you cant just ohm the wire because it will pass a ohmtest. When you load the wire (truck running) there should be very little voltage droped in that wire. If there is a big drop then you could have broken strands in the wire, dirty connections, loose connections. Im not familier with the wiring diagram for your truck, so i dont know if theres any fusible links. They will cause a big voltage drop if burnt. If your circuit from the pcm is good, which it sounds like it is, and if this wire is good, then youll probly need an alternator assuming the batteries are good.
 
Yea your quite a ways away from me. Im in oregon, south of madison, otherwise id be glad to help ya out.

You can also check the ground side of the alt by putting a lead on the alt case and neg post of battery, once again it should be below .4v or so.
 
I tried a new alternator and it reacted the same. The possibility of the new one being bad is rare but it could happen.

What amps should it draw at idle?
 
Here’s something to throw out there, the abs light is on the dash.
Would this be due to the low voltage and that the truck needs to be driven?
Or could there be a short in the system?
I would drive it down the road to see if it clears out, but I have the front tires off to make it easier to work on.

Just a shot in the dark
 
Does anyone know what amps are drawn at KOEO and KOER (with most accessories turned off i.e. radio, headlamps etc)?
Thanks
 
Well finally the truck is fixed!!!!
It turns out my alternator was bad, when I had it tested by somebody that actually knows something, it tested good at first then it tested bad 4-5 times after that.
So I replaced it with the HO 140 amp alternator that fords recommends for single alternator trucks.

Thanks for all the help guys ; this one was definitely a head scratcher
 
Did the guy ground the pin in the back and full field the alternator and not get the ammount it should have given?
 
I'm not sure what was done to test it, I had my father take it in to be tested while I was at work.
I know on further inspection we found the slip rings were grooved and cracked and the brushes were heavily worn.
 
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