Hi all,

I have a 2001 Ford F-150 Lariat, 5.4L 4x4 crew cab. I love this pickup and have become pretty handy at fixing little things, but I have head scratcher I can't figure out. Tuesday afternoon the battery light came on and then turned off. My brother disconnected the battery and cleaned the posts and cables and tested the battery and alternator. It was only putting out 11.7. I was able to make it home and by the time I got there, all the gauges were dead. The whole thing was graveyard dead. I called for a tow truck the next morning and went out the clean the inside when I noticed the dome light on, so decided to try and start it. It started right up with no battery light on. It went off and on throughout the day, but never drained the battery. The mechanic where I work hooked up his computer and there were no codes, and the battery and alternator showed charging normal...while the battery light was on. Today, same situation. The battery light goes off and on at will. I just learned there is a fuse, so wonder if that could be the issue? I'm also wondering if it could be the wiring harness from the alternator to the battery connection. I definitely don't want to buy a new alternator if I don't need one. The battery was purchased 1/2022. I appreciate any suggestions!

Thanks!

 

The first thing you need to have done is to determine why it was showing only 11 volts when it should have been more. Some vehicles have an alternator pulley clutch that may not be working correctly. Your best bet is to have a qualified shop check and diagnose the problem. There could a few possibilities and each one has to be verified working correctly before replacing anything. In the absence of any codes , is where you need an experienced tech to check the system thoroughly. Sounds like they were all guessing and that can get expensive and disappointing.