On the road with RV and notice battery light was on. Voltage meter was flashing and showing 11.9 12.0 volts. I was about 100 miles from the nearest town with a parts store. Turned off all the lights and AC (100 degrees outside). After about 40 miles volts dropped to 11.8.... Finally got to a Napa store and they had a NEW alternator. Changed it right in front of the store. Same! No change Low Voltage 11.8??? What now??? Towing a trailer in a town I don't know and it's Saturday afternoon! Parts guy said mechanic down the street is still open. I figured what the H--- nothing to loose Napa guy let me return the alternator. Went to mechanic down the street. Now from outside appearance I would not have stopped at this shop but I was in a fix (wife was getting hot and dog needed to take a leak). Mechanic tested and said yep 11.6 volts. He then disappeared and came back with a voltage tester... Did you know that there was a 5 amp fuse for the voltage regulator under the hood next to the drivers front fender? He tested fuse and it was popped! Put new fuse in and charging once again!!

Mechanic says it's possible my alternator could have blown the fuse and suggested that I replace it. It was the original 17 year old 185k alternator so I went back to Napa to rebuy the New alternator I had just returned.

Anyway long story but thought I would pass on to check the 5 amp fuse if your alternator stops charging...

 

Thanks! good info

 

Great info! Safe trip.

 

I had no idea, thanks for the tip, happy travels.

 

This is quite common through some 2000MY. I saw it a lot.

That is the fuse for the "sensing and switching circuit" (kind of an on/off switch for the regulator). It is wired to the charge indicator lamp on the dash. If the circuit is open (blown fuse) the alternator does not receive the signal to charge and the lamp illuminates in the cluster.


While a failure in the alternator (Stator Grounded) will cause the fuse to trip, the more often cause is the harness between the valve cover and the under hood power distribution box. Which, sometimes rubs on the bracket and will cause the same issue. This is the (+) wiring from the molded plug that attaches to the alternators regulator and shorts the circuit.

You may want to take a gander there to see if it has rubbed. A piece of 3/4" Convoluted Tuning over the harness will both protect and prevent a reoccurrence.

 

Somebody is watching over you. What are the odds that some little nondescript shop will have an owner that is knowledgeable about that minuscule cause of no charging on Fords. And that you would find him when you are in such a bad spot and out of town. Sometimes the strange coincidences in life are hard to understand. If you had not found him, you would be buying extra batteries and a battery charger to get home.

 

Never judge a book by it's cover, never know what you may find inside.

 

You got that right. Right place at the right time!