driving my 2001 F250 home on highway- towing a trailer (not heavy)- battery light came on- it went off once or twice when I hit brakes so I thought it was something in the trailer wiring... unhitched trailer and drove to work today and it's back on..... all systems seem to work and the battery gauge is normal. I will bring it in to have checked but wondering if anyone has a guess on what might set it off?

 

I had a similar situation. Turned out the stud on the back of the alternator was loose (not the wire but the stud into the alternator). I was able to tighten that nut and problem solved.

Good luck!

 

I have a reman Motorcraft alternator sitting here waiting for me to install because I have the same situation. I haven't looked at it at all and it would be awesome if I find a loose stud.

 

Get the battery load tested first. Voltage testing does not mean the correct amount of amps are being pushed. Can also remove the alternator and have it tested as well. Any local auto parts store should be able to do these. Oreilly's, Autozone, Car quest, napa etc.

 

I was getting an intermittent battery light at higher rpms.

The culprit was an excessively worn brush. Only 68k miles. Did a complete rebuild to fix the issue. The slip ring was grooved pretty good.