My truck (1995 XLT 4.0 OHC Extended Cab) has been in the family since it was new. My late father-in-law treated himself to an 80th birthday present in 1995 and sold it to me 3 years later with only 3,000 miles on it. Truck now has 80,000+ largely trouble free miles. The truck is well maintained and driven regularly on local streets and interstates. Never wrecked. When it turned 25 it started acting up. In the previous 23 years it had only few problems: AC seals dried out (from non-use) at age 3 and fixed under warranty before I purchased it (that country Ford dealer fixed AC that blew cold for another 22 years until I had to replace most of it); brakes failed after about 15 years and after failed efforts at the dealer (2) and independent shop (2) found a reliable shop that fixed it right for good; driver's power window motor replaced by the dealer twice about 10 years ago; RAB stopped working about 15 years ago (never fixed). But she has gotten cranky in her old age. The notorious CHML water leak materialized and I tried every trick I could find including aftermarket replacements. Nothing worked until I bit the bullet and went OEM. $$$$ part when all it needed was a gasket! Works. I replaced the power window and door lock switches when cleaning them up did not resolve intermittent problems. Cheap and easy fix. Annoying issues but given its age I cannot really complain. But now she has developed a show stopper--unpredictable intermittent starting problems. In the first 25 years it never failed to start easily on the first go. I could always count on it. Now it's a roll of the dice. AAA jump started it last summer and said battery was OK. That worked for a week or so and then it almost left me stranded at a store parking lot after being shut off for about 5 minutes. Almost gave up but jiggled the key while attempting to start 3 or 4 more times and it fired right up. Until a few weeks later it did the same thing. Had it towed to my mechanic to replace the ignition key switch. He also thought the alternator was an issue. After 25 years, OK do it. Worked fine for a month. Repeat. He replaced the alternator. Good as new for 3 months until it wasn't. Fired up quickly on the first go every time. Dead again so I am on the boards trying to sort this out myself. Going out now to try a few things I learned here. If I fail, I will post details on the starting issues in the proper forum.

 

Welcome to the forum

Ranger charging system is very easy to test if you have a Volt meter, 3 wires to test, its that simple

Key off
Test battery voltage first, 12.3volt to 12.8volt is an OK battery
Under 12.2volt is a failing or drained battery

But you need the battery volts regardless so remember it
Wire 1, on the top back of the alternator is the B+ terminal, stud/nut connection
Use the alternator metal case the the ground(for all tests) and then test voltage on B+ teminal, should see "battery volts" exactly, if not a Fusible Link is blown

Unplug the 3 wire connector on the alternator
Wire 2, there is a Yellow wire in the connector, test it, should see battery volts exactly, if not the ALT fuse is blown in engine bay fuse box

Wire 3, light green wire on same connector, test it should be 0 volts
Turn key ON, engine OFF
Test green wire again, should see battery volts but can be .1-.3 less now

If all 3 wires test OK then Truck part of charging system is GOOD, 100% working, 0 doubt

Plug 3 wire connector back in, make sure white jumper wire is also plugged in to it single spade terminal
Start engine
Test battery again, should see 13.5-14.5volts, alternator is working
If you still see "Battery Volts" then replace alternator, FOR SURE, don't care it is brand new, it ain't working

People often replace a battery FIRST when starter motor doesn't work to start engine
If you do this and don't test the charging system, as above, then you can RUIN a brand new battery

Car battery are made to discharge 60-75amps all at once for starter motor to turn engine over
Then they are not used at all until the next start up
When an engine is running ALL electrical power comes from the alternator, it MINIMUM voltage is 13.5volts, a batteries maximum voltage is 13volt(brand new), 12.8v normally
So when engine is running electricity flows TO the battery to keep it charged up, no voltage comes from the battery, it can't

A car battery is not made for use in a constant drain system, like say for an RV where it runs the lights for long periods, those types of batteries are call Deep Cycle batteries

So if you replace the car battery and alternator isn't working or not working well, then the new battery is being constantly drained while driving this will ruin a new car battery in a few months

So always test charging system when you have a "dead" battery, because it could be "dead' because of the charging system or ruined because of it

New battery is 12.8volts
3 year old battery is 12.5v
5/6 year old battery is 12.3v <<<<< and time to shop for battery sales
12.2v or lower get new battery now AFTER checking charging system

 

Thanks so much Ron for such a thorough check list. Before I attempted to start the truck again yesterday after my post, I shot a little Deoxit D5 into the key slot and it fired right up. Maybe just coincidence. It is an intermittent problem. I didn't check the gauges when I did because I was in a hurry to move it off the street due to forecasted snow. Maybe I just got lucky but I got it out of harms way and left it at that. It being a weekend I did not want to tempt fate by messing with it further and risk needing a tow to a closed shop. Snow is falling now. After the storm I will move the truck (hopefully) back to a space where I can work on it and try these checks you recommended. The detail is very helpful. I probably would have just thrown a new battery into it today but for the weather. It is in the 5/6 age range. I will run these tests before putting in a new one so I do not risk ruining it or getting stuck. I really want to be sure whatever this problem is it is solved in a way that I can be confident I or more wife will not get stranded.