I have a 2000 Ford Excursion XLT 2WD with just over 155,000 miles on it, for awhile now My battery light has been on and off or it'll flicker and some times it will even stay solid. I checked the batteries and the alternator a while ago and got good readings from them. I just thought it was a code that never got reset. Well this morning I was driving it and I noticed that when I brought the RPMs over 3,000 the battery gauge would go up to 18 volts and the battery stayed on until the RPMs went back down past 3,000. It did this all morning until I got home and just for kicks I put it in park and revved the engine up to 3,000 RPMs, when I did nothing happened. I tried looking online for an answer and I called a few mechanic shops who all said it was my alternator. Before I go and dump another $150 into this beast I want to make sure that it is in fact the alternator

 

Alternator! they go bad and when that happens you get the battery light. make sure you get a Ford reman! parts store remans are junk and will not last very long!

 

How much does one cost from Ford?

 

Depending on what engine you have between $220 and $260 for a Ford reman.

 

Call this guy. https://alternatorparts.com/

I have no affiliation, hes just a good guy with the best parts. Its worth a call if nothing else, just to get educated a bit.

Mine did the same thing, it was intermittent. Its the rectifyer/regulator taking a poop on you.

 

I have the 5.4L V8

 

Okay I will check it, thank you

 

Retail is $238.48

 

Well that's not too bad, I appreciate your help

 

How did you check them and what readings did you get?

Stewart

 

I used a voltmeter, And when I had the engine off I got 12.75 from the left battery (facing the truck) And 12.73 from the right. I turn the headlights on for 5 minutes and checked them again and got 11.97 from the left battery and 11.98 from t he right one. I turned the truck on, let it run for a little bit and I got 14.3 from the alternator which kinda led me to believe it wasn't going bad, I got 14.12 from the left battery and 14.09 from the right one. I got a new alternator and put it in this morning and it's running beautifully now, no more battery light on the dash. I'm 2 major problems away from having a perfect running excursion!

 

11.97v after only 5 minutes. You need to have your batteries charged(with a proper charger) and tested. They are flat at that voltage.

 

Well I didn't just have my headlights on I had a bunch of electronics on inside the truck. They seem to be fine now but just to be sure I'll take it to an auto store and have them test the batteries. I have no idea when they were last replaced because I bought the truck 10 months ago

 

In the future, just refer to the "sides" as drivers side or passenger side. Much easier than left or right with a qualifying statement.

Glad to hear you got it fixed.

Stewart