I have a 2003 F250 with the 5.4L motor. Last weekend the battery light came on and the next day I broke down. Truck started up just fine but died while driving down the road after loosing power. Took the alternator out had it tested and it failed which I kind of expected. I replaced the alternator with a new one and a new serpentine belt. The battery shows 12.5 volts and then 14.4 while running. The battery light is still on. Both battery terminals were cleaned. Kind of at a loss here. Thinking of having the battery tested and get a new battery. I had the battery on the charger for an hour today just to be sure. Tried finding an alternator wiring harness diagram but have become overwhelmed trying to find the exact one. One other question is should there be three wires entering the alternator? It has three pins but my harness only has two wires to the plug (3 slots). Thanks for helping a newbie here.

 

Might be the battery cables themselves going bad. Relatively simple to try new ones; hopefully that will fix it.

 

check out this thread; https://www.ford-trucks.com/forums/9...-charging.html

It appears that it is likely related to the connector that you are holding. Have someone wiggle it a little while you watch the light.

 

I have been having battery issues, went to YouTube and found some videos about the big 3.

The terminals on mine are in poor shape.

 

Update: Problem fixed. New alternator was defective. After checking all wires, fuses, battery, etc. Decided to bring back the new alternator. Exchanged it for a new one and the battery light is now out and everything appears to be in working order. Thanks for your suggestions. Wish I hadn't wasted so much time trouble shooting a problem that shouldn't have happened. Brand is Duralast and has lifetime warranty.

 

Glad you were able to track down your issue. And thank you for coming back to report the resolution to your problem.

 

I learned a long time ago to test alternators and starters in the store before paying for them. It's saved me several times when the "new" item failed the in-store bench test.