Greetings everyone. I'm new here but enjoying what I have seen so far.
I just bought a 99 Ranger XLT from a friend. One owner till now. He had to change the fuel pump and told me it needed a battery and maybe an alternator. I bought a re-con battery and saw it tested. Got it home and checked. Not charging. Lifetime warranty on the alternator so I exchanged it.
Belt is good as is the tension. Fuses, the ones I have found, are good. Still not charging.
Any ideas where to look now ? Thanks everyone ! Have a great day !

 

check the positive battery cable that connects the battery / fuse panel to the alternator

they get moisture corrosion over time -- connection fails

 

The Battery Light circuit turns the alternator ON and OFF, yes alternators have an on/off switch, otherwise they would drain the battery when engine was off.

On the 3 wire connection on the back of the alternator, there will be a Light Green/Red stripe wire, that's the on/off wire, it runs to the Battery Light.

When you turn the key ON the ignition switch sends 12volts(battery voltage) to the Battery Light, then thru the battery light to the Alternator(LG/R wire), the alternator is now on but if engine isn't running, the alternator is 0 volts(a ground) so Battery Light is ON, current is flowing.
When you start the engine the alternator produces 13.6v(approx.) so system is now 13.6v , at both sides of Battery Light, so no current is flowing thru the bulb and it is OFF.
If alternator voltage ever drops below Battery Voltage(12v) then Battery Light comes on again, current is flowing thru bulb.

Battery Light circuit has a 500 ohm resistor in case bulb burns out, so alternator can sill be turn ON and OFF.

 

Checked that. Charged the battery and took the truck to Advanced Auto. They found the problem. 75 amp main fuse. I bought one, they changed it and running fine ! Thanks cheese-man and Ron. Now, it needs a bath.

 

yes good to know

over time fuses do blow for no reason