My battery light came on hte other day, off and on, off and on. Then nothing for a couple days. Yesterday it came back, on and off, on and off, and today nothing. I just replaced the alternator 3 months ago and hte batteries 9 months ago, and when they went the battery light never came on. Any idea what might be causing this? Thanks.

 

What alternator did you get? As a first step, I would suggest that wherever you got it needs to test it for you.

 

You might also verify that all connections are clean and tight to include grounds and exciter wire on the alternator.

 

Where did you get it?I put an alternator on the Ex this summer it was a napa,three months later I had to replace it.I put a oem from ford back on it,my 350 has a dixie on it as a replacement and has been trouble free for a about a year now.

 

It's an ebay reman. I tested everything when I got it and all tested good. Gotta hook up again to see what it's putting out, but I'm thinking that little plug that goes on it is broken or loose or something.

 

Do you have a Voltmeter? I got a new (reman) NAPA alternator and it went out on me in 6 months. Anyway my dummy light came on and off and i noticed that it only came on above like 2500rpm's. I put my volmeter on it and had my girlfriend rev it up while i was watching the voltage on the battery and sure enough when it went above 2500 rpm's the voltage dropped to like 11.5 or something like that and it was 13.8ish at lower rpm's. Any case I think you got a bad alternator.

-Torsten

 

Jay, my light is doing the same thing...comes on and off for a quick bit about once a week or so. I load tested both batteries and tested the alternator and all 3 are above par. No corrosion on the terminals either. I'm baffled.

 

I have an 03. Replaced the ficm and 1 hour later my battery light would come on and would stop charging ( I have a voltage gauge ) when ---I accelerated or when at a stop light, when cruising the the light would drift off and on, light would be off at a stop in neutral or reverse. Alt charging, light would be off---light would come on and it would not be charging. (I have replaced 3 alt in past years and the bat light never came on) I replaced the alt with a remain Motorcraft from Rockauto, same thing. Took the truck to the dealer, could not find anything but gave me a reflash so I would not waste the diagnostic fee. Suggested to send alt. in for replacement. I figured these guys were nice to me so I bought another motorcraft at the dealer and installed myself---same problem. Had the holy crap moment later that night when I would hit a manhole the bat light would also flash (we don't have potholes in Fl) The next day I pulled any connector I could find and did the old jiggle the wire thing-- Bingo- battery lights out, charges as it should and I have started a nice alternator collection. Batteries are charging and the reflash made the truck idle and run the best it ever has. But there is always tomorrow with a 6.0