2004 ranger 4.0 wont charge changed alternator still nothing
batt light works and is currently on
battery is good
volts good (12) at alternator post
key/off yellow/white wire at alt plug fluctuating 5-9 volts
green/red wire at alt plug is batt voltage with key on
no blown fuses
can anyone steer me in the right direction?

 

Welcome to the forum

Bad connection on Yellow wire, should be Battery voltage(12v), key off or on doesn't matter, its hooked directly to Battery Positive via Fusible Links, same as B+ wire on back of alternator(black/orange stripe wire)
Disconnect the 3 wire connector to test those wires

Fusible link is a shorter wire(6"-8") that connects a Load to the battery, like an In Line Fuse, but a Slow Blow fuse, cheaper version
They are on the Fuse box end of alternator wires, inside the harness usually so you have to do some unwrapping

Wiring diagram below, there are 3 Fusible links, 2 are Grey wires and one is Brown(on 4.0l), all 3 need to be checked

Green wire is the only wire that is Key on 12volts its also Battery Light wire

 

Thanks for the reply ron,
Not sure I'm getting you. You say it's hooked directly to the battery positive same as B+ wire. I dont see any yellow wire anywhere near batt pos post
i also not sure what you mean by fuse box end of alternator wires
I have 2 heavy red wires connected to the battery pos post, i assume one goes to alternator and the other feeds the front of fuse box and is attached there by 2 10mm nuts. I dont see any yellow/white there
the only other wires going into fuse box are a big fat bunch from the harness that is all small wires to each fuse i guess. dont see yellow/white wire there.
where am i going wrong?
thanks, Tony

 

looked at the diagram. what is a battery junction box?
unfortunately the diagram gives me no clue where to look for the fusible link

 

Engine bay fuse box is the battery junction box

Look around the outside edge for a terminal, or follow the smaller Positive battery cable to the terminal

Yellow alternator wire will connect to a "brown" fusible link wire, which then connects to TWO "grey" fusible link wires and the Black/orange wire

Then the two "grey" wires connected to Battery Positive wire

 

ok ron.
my owners manual refers to the fuse box as a power distribution box
so are the fusible links near the box or near the battery?
the diagram looks like the fusible links all connected together. are they? not sure what dotted line means.
thanks very much.. i'll go out and start unwrapping wire

 

Follow the smaller Battery Positive cable.

Yes dotted lines are connections
The two Grey fusible links are connected together at each end(in parallel), one end of this is connected to the battery cable(S130)"Splice 130"
Other end is connected to Black/orange wire from alternator's B+(S131)
Also connected here is the Brown fusible link(S131)

Other end of brown fusible link is connected to Yellow alternator wire

Ford "tries" to maintain wire color codes every model year, but they are "guide lines" not written in stone, written in chalk on an outside black board in a rain storm :)

Pictures of fusible links:
https://www.freeautomechanic.com/mec...ks-300x181.jpg
https://www.ford-trucks.com/forums/attachment.php?attachmentid=57616&stc=1&d=13417056 36
https://images-na.ssl-images-amazon....dL._SX425_.jpg

"Most" factory fusible links will have the marker saying "fusible", but not all, again Ford tries to do it but................

 

ok ron,
I found them. pretty close to battery terminal. kinda a cluster you know what of spaghetti.
as i start to peel back the heat shrink? covering splice im greeted by lots of green copper corrosion.
the two gray ones have battery voltage each side
the brown one does not and that is our yellow/white wire
probably next to no connection being made which may account for my 6-8 volt reading at alternator plug.
the link does not appear to be melted, as its still stiff
ill dig a bit deeper
thanks ron you know what end is up for sure

 

Hey Ron,
Cleaned up connection a bit and clamped the brown wire to splice. Eureeka! we charging again.so my problem was a corroded splice at the fusible links.No visible signs anywhere.
Can't thank you enough for taking the time to help me out. I googled a lot of info and all I could get was I knew my voltage wrong at plug but I didn't know if I was looking for a fuse or what as the culprit. The forum is lucky to have you as a member.
Tony

 

Good work

Thanks for the kudos and posting update and the FIX, it will help others