Why is it not charging????

midnight2004

midnight2004

Just about broke
Joined
Jun 18, 2006
Messages
195
My truck is not charging and I don't know why, tried a new alternator and no luck. :bang
It runs at about 12.4v with freshly charged batteries and went down to 8v when I was driving around, with no voltage light on.

With the truck idling the alternator became extremely hot to the touch is that normal?
Batteries are brand new.
 
check the 3 pin connector to alternator to ensure good contact. the red wire of the connector has a fusable link that could be open. it is grey at that point on the wire.
 
fordfan30 said:
check the 3 pin connector to alternator to ensure good contact. the red wire of the connector has a fusable link that could be open. it is grey at that point on the wire.
Click to expand...

Thanks, I just checked it and;
The orange wire at the connector reads 12v unplugged and the green is ground.

Any other suggestions?
 
There is more than 1 fusable link in that line. Voltage drop across the charging wire from the alternator to the battery? What is the voltage of each battery disconnected from each other? 12.6 is a fully charged battery. If you lose a cell, subtract 2.1 for each. The battery should stay above 10 volts for 15 seconds with 80 percent load on them. If they are dropping to 8v you may have a few cells dropping out.
 
Thanks,
I'm going to try this when I get home.
I'm going to take the charging wire off and see what it reads at the alternator when its running. Then I'll load test my batteries.
Man is this irritating. I hate electrical gremlins.
Thanks again!
 
well if it's hot I'd say it's trying to charge, but is feeding into a major load. Check both batteries, individually, ie take the ground wire off each one separately and check the voltage. I'd be willing to bet you have a dead battery, or at least one with a bad cell.

Failing that, you need to start hunting down high current circuits and verify that they are doing what they're supposed to be. I don't know if you have a winch, stereo or other accessories, but these are all potential sources of high load that might be going unnoticed.
 
Thanks,

the only high load on the truck is a fass fuel pump otherwise there is nothing else major.
 
midnight2004 said:
Thanks, I just checked it and;
The orange wire at the connector reads 12v unplugged and the green is ground.

Any other suggestions?
Click to expand...

I think both wires should be 12v if the alternator should be charging. Ground comes from the mounts.
 
riggz said:
I think both wires should be 12v if the alternator should be charging. Ground comes from the mounts.
Click to expand...

If that is ture then there is a problem, because when i run my meter leads from the positive terminal to the green whire i get 12v.
 
Go look in the Bible, and look at the schematic, I think it's towards the back... you should be able to tell what's going on from there.
 
The A/C blower motor on high pulls just at many amps as the fass does. Like I 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.
 
We got a truck in one time that was killing batteries and we found that it was because someone had the cab off and broke the ground strap between the cab and the frame under the passenger side.
 
take the the 3 pin plug apart on the alternater make sure u don t have a broken wire mine did the same thing as urs that was my problem
 
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?
 
mine 05 is doing the same thing.
as soon as the light came on, i took it to ford and put on a new alternator and two new batteries.

light remains on and only have about 12.6-12.9 volts.
oh well haha, drive it til it quits :rockwoot:
 
This is where I’m at:
At idle:
12.36v
60 amps drawn

Alternator red battery wire disconnected meter black lead on negative, red meter lead on alt terminal reads .37v

High idle:
12.62v
69.8 amps

Alternator red battery wire disconnected meter black lead on negative, red meter lead on alt terminal reads 8.015

According to all data it should be:
Base voltage is 12v
No load at 2000 rpm 13-15v
Load at 2000 rpm min .5v above base voltage.
They also state a service bulletin for single alt trucks w/ plows or accessories should replace their alt w/ 140 amp alternator.

Not sure if I should just button it up and try driving it or what, I would think the batteries would read 14v at idle.
 
Also the 2 wires on the connector read as follows:
Orange (batt) is 12v; black meter lead on gnd, red lead on wire

Green (I sense) is 12v; black lead on positive battery, red lead on wire.
 
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