Hello all, new to the forums here, but I have no clue as to where to go from here. I have a '91 Ranger 2.3L (the stupid one with 8 spark plugs). Last week, the truck died on me, was able to pop start it and drive it home. While driving I had no brakes, turn signals, headlights or electrical instrument cluster (only things working on the cluster were oil pressure and speedo, since those are analog sensors). Deduce that I was driving on the battery, pull the alternator, and the windings are completely jacked (you could hear them when you spun it by hand). I order a new alternator on amazon, since NOBODY in town had one (Autozone, O'reilly's, Napa, Merle's, or Advance). Get it, install it, and the truck will still not charge the battery. I just checked continuity on the wires on the alternator back to the PDB, and all was good. When the truck is running, I get 12v across the first 2 wires on the rectifyer (orange and blue, black and orange) and 6v on the white/black wire. What am I not seeing? What should I check?

 

Welcome to the forum

The light green wire on the alternator's 3 wire plug is the Start Up voltage for the alternator, also Battery Light
It should nave 0 volts key off
12volts key on, this 12v comes form ignition switch

this Light green wire is the ON/OFF switch for the alternator

Yellow wire on same connector should have 12volt key on or off, from 60amp fuse

B+, alternators stud connection, Orange/blue, and Black/orange wires should have 12volts key on or off, from another 60amp fuse

 

all those check out as well.

it has a built in regulator with 2 plugs. one that has 3 wires; the orange/blue, black/orange and white/black. another that has white/black, light green and yellow/white.

Looking at the wiring diagram, the white/black wire goes between the two plugs, and i have 6v across this wire. all other wires I have 12v

 

Forget the white/black wire, just make sure its plugged in to the single connection

Unplugged from alternator
Light green wire has 12v with KEY on <<<<important

Unplugged from alternator
Yellow wire has 12v all the time

B+ wires have 12v all the time, they can be connected/plugged in

And always use the alternators Case as the ground when checking voltage on these wires, not battery negative

Hook wires back up

Start engine
Battery voltage should be 14+ volts, if not alternator is bad, new or not

Charging system is very very simple to test
B+ 12volts all the time
Yellow wire 12v all the time
Light green wire 12v only with key on

And thats it, if these test OK then alternator is bad, no doubt 100% accurate