I had the exact same symptoms at almost the exact same time and was considering the afterlife until I checked fuse #11 for the 5th time. It looked great, it looked clean on the contacts and for some strange reason I thought I'd just check continuity since I had the meter there. It was open, I looked at it again and it looked perfect, almost. Along the one side there was a hairline crack. When I twisted the fuse in my hand the thing opened up. I invested $3 dollars in a whole bunch of fuses and one of them did more than the new alternator I bought, the new serpentine belt, the witch doctor....

 

Well my neck is about worn out from shaking after reading how many times people say things look ok when trying to solve a problem.
Looks don't count more than half the time as you found out.
Have to test operation or some indicators, if operation is infact proper.
There are meters, gauges, scanners and knowledge that has to be used otherwise, money, time and aggravation is spent, as a result.

 

I got the trusty alternator out, and tested at the battery. It showed just over 10 volts, didn't change a bit when I reved the engine, I tested on the alternator side of the Fuze link, and it was the same voltage. I then tested the voltage on the actual alternator post that leads to the battery, And it showed the same voltage even when I reved it, I am assuming that there should be a higher voltage coming directly from the alternator. I guess I will take off the alternator and make another trip to the 'ol autozone and see if I can find someone who is capable of testing an alternator correctly.

 

Update... I went to auto zone, and the alternator was good, Which leads me to the harness, which is about the only thing I think it still could be. I'm going to have to call and see how much those run exactly.

 

try a different brand alternator. its possible to have a run of bad alternators

 

Well I brought it in yesterday to Village Auto Electric in Mesa, They had it done in less than a day, and it was 130 bucks. It was the wiring harness to the alternator, apparently one of the connectors was corroded inside of it, they replaced part of it, and low and behold no more battery light. Praise the sweet lord, I can finally drive my truck on its sweet new BFG Tires that have less than 20 miles on them. Thanks to everyone who helped me w/ this, and I hope this helps anyone else with a similar problem.

 

Had a charging problem on 2000 f250 6.8. Found 12 ga fuse able link bad. Could apply 12 volts to orange wire on regulator and alternator would work. Wire had battery voltage on when unplugged from alternator, but only 5 volts plugged in.

Just a heads up. Found this thread on good search for charging problems.

 

I bought a cheap alternator from TYC ($80) to replace my stock that had gone bad. Although it preformed well as far as output etc. the battery light and "check charging system" warning stayed on. After ruling everything else out I figured out that the cheap replacement wasn't compatible with the computer. I guess ford still has a monopoly on compatible replacement alternators. I probably could have driven it with the light on and it would have been fine. I paid $200 for a rebuilt (carquest) from Autozone and the light went out and it works fine. (Plus its guaranteed for life). Hope someone finds this helpful. Mine is a 2004 F150 lariat.

 

Hi All,
I own a 2001 Ford Excursion and like many on this forum, struggled with the alternator not charging the battery. I spent hours and hours troubleshooting and reading forum posts. I swapped out a new alternator when it wasn't charging and the 2nd "new" alternator wasn't charging either. Here's what finally solved my problem...

The main power wire that runs from the positive battery terminal to the 3 wire connector that plugs into the alternator isn't providing 12 volts to the alternator (required to active it). The strange thing was that if I disconnected the connector and measured voltage when the engine was off, I had 12V. If I connected the connector and measured voltage while the engine was *running*, it would drop down to ~ 1V. I'm not sure why. It took me a while to figure this out though. Anyway, I wound up running my own wire from the positive battery terminal to the connector (soldered / spliced the wires) and capped off / taped the original power wire. The other 2 wires on the connector are hooked up in their original configuration.

That did it! I now have ~ 14.6V when running the car across the battery terminals.

I thought I'd follow up with this post in case someone can learn from my experience.

Regards,

-Jason

 

I have the same problem.
Light stays on even after replacing battery and now my 3rd alternator in 3 weeks