charging issue, not charging

[kbecker3]

2003 ranger 4.0 not charging.

with key off:
battery voltage at 12.3 volts
at alternator: black and orange wire: 12.3 volts
green and red wire 0 volts
yellow white wire 12 volts

black and white wires have continuity between terminals

with key on green and red wire goes to 12.0 volts

start vehicle, same voltage, maybe slightly lower…
Did notice when you do a continuity test between case of alternator, and the terminal of the black and orange wire there is no continuity while vehicle is off, but when its running its has continuity.

Fusibile links have 12 volts on either side of the link and continuity. Only other thing i noticed is battery light does not come on when key is turned. would have thought it would unless its burned out. but my brother said it comes on if you drive with lights on. I did not notice it come on while running, or not running with key on.

At a loss, the original alternator was doing the same thing tested fine. Got a rebuilt one from advance, still doing the same thing.

any help or ideas would be greatly appreciated.

 

[Haywire6000]

Battery light should come on with the key on, in the run position without the engine running. If it's not charging while the engine is running then the light should be on.

Check all fuses and connections.

 

[kbecker3]

I figured the battery light was just burned out since i am still getting voltage with key on at the green / red wire at the alternator wire harness. All the wires seem tight, checked almost every fuse, didn't see one labeled specifically for the alternator. It seems like it is something really easy.

continuity between alternator case and neg. battery terminal too.

The only thing that really stumps me is why would there be continuity between the battery output terminal and the case of the alternator while its running? But no continuity between the two battery terminals.

My 02 ranger does not have that. It works correctly.

 

[enjr44]

When did Ford go to the ECM controlled alternator? I thought it was sometime around 2003/4. I don't think any of the old rules apply to those.

 

[kbecker3]

Just wanted to say i figured it out. It ended up that the battery light was flickering on and off very faintly.... Guessing the fuseable link was burning out and not completely burned out? I had correct voltages on all wires when i checked them the other day. Today didn't have any volts on the yellow / white wire (constant through the fuseable link). Replaced and now charging as it should. must have been making enough contact to not turn battery light on, but not enough to tell regulator how much charge the battery had.

Anyway, fixed and working hope this helps if anyone else is having this problem.