I have a 2005 xl 2.3 and it charges some but not a lot. Here is what's going on.

Started with battery light coming on and truck shutting down. After checking fuses, connections, wires then I decided to get a new alternator. Tested voltage while starting and running... Voltage around 12.9 to 12.5. This voltage has remained constant with 2 new alternators. Battery light still on and there is no telling when it will finally lose all power. But it will mess with you and charge the battery after a jump! I am completely dumbfounded.
There is no megafuse at fuse box.
All fuses replaced for good sakes.
Continuity is good.
Everything that I have tried checks out and I have searched forums for about a year.

Any help or any direction is greatly appreciated.

Thank you

 

You might check out a few of these diagrams to see if you're missing anything.

Wiring Diagram Search Results

Are you getting 12.5-12.9 at the back of the alternator?

 

Yes I am getting those voltages at the back of all 3 alternators I have installed. The truck has about 120k on it and it is very clean (no oil, fluid leaks) and I can not see any corrosion either.
I am going to check the diagrams you have shown me now.

Another question... Why would my ranger not have a mega fuse? This engine gets me.

 

Hmmm....not sure on the mega fuse. But I bet someone else here on the forum does.

Since you are getting that voltage at the back of the alternator, maybe you have a bad ground or two or more? I am mostly positive that you should see at least 13.5-14.2 at the back of the alternator.
Could be corrosion of the ground wires inside the insulation. Had that happen on a 2006 Ford 350 Powerstroke one time.

 

I will double check the output from the back of the alternator again n the morning. And will update ASAP. Thank you.

 

2.3l should have 3 wires at alternator

Key off test these wires, use alternator's case as the Ground when testing
Larger B+ wire should have Battery voltage, i.e. if battery shows 12.5v then B+ should show 12.5v, you can leave B+ wire connected to test
If low or no volts then you have a blown fusible link
There is no Mega fuse just two fusible links for the 2.3l in 2005

Unplug 2 wire connector
Yellow wire should have battery voltage, if not the same fusible link is bad or if B+ has battery voltage but not Yellow wire then a different fusible link is bad

Green wire is the ON/OFF switch for the alternator, this wire comes from the Battery Light in Dash
Should have 0 volts key off
Battery voltage with Key on
2 fuses to check for this one, fuse #9 and #10 in cab fuse box

Battery light gets 12v key on, with engine off Alternator is a Ground, so Battery light has 12v and Ground, so lights up
After you start the engine and alternator is working, Battery light bulb now has same voltage on BOTH terminals so no light
If battery light stays on then alternator is still a GROUND, not producing any power

If green wire shorts to Ground then alternator can not turn on and battery light would stay on when key is on

 

Recap: Solved ... So I went through 1 alternator that was rebuilt by a very reputable business. So I put in on and in the process cleaned and tested continuity. Checked fuses, etc.... Nothing. Went back to very highly reputable recommended alt repair shop again. Bought a completely refurbished alt. Looked brand new. Put it on and no go. It would give me 13 1/2 volts and then not charge then charge then not. I checked main fuses, relays, voltage out of back of alternator. Drove vehicle to alt place and they said it would be fine. In the mean time it would act up and battery light stayed on. Finally after just deciding the best alt shop in town sucks I went to oriellys bought a new alt put it on and it is working perfect. Spent 140 on shop fixing it and refurbished. Spent same on new one.
Thank you to everyone who posted! Anyone in the future just buy a brand new one.

Thank you guys and Girls

 

So it was the alt after-all.
I was thinking that your battery was old _ wouldn't take a charge anymore.

I have to say, from reading other posts, the alternators for these trucks must be pretty crumby.
Another guy went through 3 of them before he found a good one.

New and untested I can understand, but really, what are they rebuilding them with, crazy glue and silly putty


I'm glad I rebuilt my own.

 

I am glad your truck is working, knowing the alternator is working I would still look into the Fusible links that RonD mentioned.

They are located near the positive battery cable close to the battery, they tend to get hard and brittle the insulation cracks which leads to corrosion.

On my truck the smaller Brown fusible link was broke in two with just one or two strands of wires making contact.

You may have moved this fusible link a few times while working on the truck, while moving the wire it could be making a better connection allowing the alternator to charge.

Anyways when you can just check the fusible links to make sure yours are in good shape.