Been fixin' some issues on my 2001 xcab 5.4 4WD, did manifolds, plugs, few coils, battery. It (seemingly)suddenly developed an intermittent electrical bug. The ammeter on dash shows an overcharge condition, and the red battery icon lights up. To avoid boiling battery I either disconnect the 2 wire alt connector, or drive real slow/low rpm's to keep the amps off the peg. EDIT to add that usually it shows a normal charge. Incidentally, when I do disconnect the alt, it seems to die awfully rapidly.> I expected it to be driveable on 1000 amp new battery more than a dozen miles.

Appears the alternator was recently replaced (its a rebuilt unit, 130 amp) . Every time I have had a shop look at it/connect the batt/alternator tester it checks out "fine".

I suspect output diodes/regulator in alternator. Ideas? Would this condition also cause battery to discharge overnight occasionally?

 

Sounds like the alternator is bad, when the battery icon on the dash lights up that is an indication of a bad alternator. When you were working on the truck hopefully you didn't short anything out. Good luck.

 

I just got a rebuilt 130 amp that overcharged. Brought it back and it tested fine and I got a different one anyways. The second one worked. Those tests are not always correct.

Check out this thread and Bluegrass explains how it works.

https://www.ford-trucks.com/forums/1...or-change.html