I've never had to post before because I've usually been able to find an answer to my problems. But this one is killing me.
​​​​​​I've got a 2004 Ford Ranger 4.0L. Here's the series of events so far:

One day I'm driving and my battery light turns on. When I get home I check the voltage while it's running and it's slowly dropping and I hear a whine from my alternator. Installed new alternator.

Runs fine for about a month until one day my stereo starts cutting out, then my abs light comes on, then my brake light, and then it stalls in the middle of an intersection and I have to push to safety. Battery is a few years old so I assume it's dead without testing voltage or anything. Installed new battery.

Drive it local for a day and my stereo and sub is still cutting out. Figured wiring might be loose, so I check and tighten everything from the battery to my amp and sub and to the head unit. Go for a test drive and make it about 50 feet before the same symptom's from before the new battery start happening, and I head home before it dies completely.

Voltage testing is showing the battery can hold a charge when I let another car charge it, but my alternator isn't doing any charging. Reading battery voltage at the B+ and on the white wire of the 3 prong plug. 0 voltage on the green wire while it's off and battery voltage when it's on. All of this seems as it should from what I'm reading.

The kicker is my battery indicator light does not turn on ever! Even when I turn the key to on without starting it, and even when I unplug the 3 prong plug from the alternator. Other posts say this means a blown fuse, but for the life of me I can't find a fuse that is for that light. I checked every fuse that sounded like it might somewhat be related to the charging system and they're all fine. I even have my dash torn apart thinking the bulb for that light burnt out but NOPE. I've also replaced my battery terminals just for the fun of it now it seems.

So I'm hear hoping someone will have an aha moment that I'm not having. Hopefully before I rip out that alternator and get it tested just to be told it's fine and have to put it back again.

 

Suggestion from Courierlenny: I presently am driving a 1997 Mazda B4000 [Ford} and spent a lot of time tracking a similair problem. If you find a starter solenoid bolted inside the driver side fender near the clutch resivor, start with it. There is a heavily insulated wire coming from that solenoid and running to the alternator. This lead is about 6 inches long and is connected to the wiring harness going to the alternator. This lead is in fact a [fuseable link] designed to melt and protect the vehicle wiring. I thought that mine had melted and because of the heavy insulation it was not visibly apparent. I stripped the lead and found it intact. However I discovered that where the lead was crimped to the alternator wiring was badly corroded. I seperated the crimp and re-did it also using solder as well. Check the integrity of this [link] . I had previously installed a new alternator, and battery, also and had also replaced this starter solenoid.

 

The light green/red stripe wire on the alternator's 3 wire plug needs to have 12volts with key on, this turns alternator ON, this is also the dash Charge Light voltage

So unplug the 3 wire connector and test that wire key off and then key on, should have 12v key on, if not then no alternator power

This 12v comes from the HEC(instrument cluster) on the light green wire, so if Charge light doesn't come on with key on I would assume there is a problem with the wire or in the cluster
HEC is a micro processor dash, GOOGLE: Ford HEC
There are tests you can run on this cluster

Check the light green/red wire as best you can where it runs thru the engine bay to the firewall