Reader Question: My 1999 Ford Explorer XL 6 cylinder is having an electrical problem that appears to be killing my alternator. About a year ago, I had to replace a 175-amp fuse that is inline with my battery and alternator. I had already replaced the battery and the alternator before I learned about the 175-amp fuse.
So basically, I have all new components. Everything has been fine until recently, when I got in my truck one night and noticed my dash lights going dim and my battery indicator was lit.
This was the same symptoms. I had before when the fuse had blown, so I checked the fuse. I put a meter to it but it was not opened. I did just the basic disconnect the battery while the engine was running to test the alternator, the truck killed. The alternator was still under warranty so I replaced it.
I cranked the truck with the new alternator and it appeared to work fine, the battery light on the dash went out and the gage indicated that the battery was charging. I turned on the dome light and almost immediately the battery light came back on and the gage indicated that the battery was no longer charging.
It appears that somehow there is a power surge that is killing the alternator. But I am not sure what it could be or what component is causing it. Any Ideas?
Thanks for your time and any help that you can give.
Have you had the alternator output checked and the battery load tested? It sounds like a bad voltage regulator inside the alternator to me OR a battery with a bad internal cell.
I would get an electrical test, check the alternator output, load test the battery, and go from there. Check the connector at the alternator too, sometimes they overheat and physically melt causing an internal short.
Also, make sure the battery cables are clean and tight, you should not be able to easily move the cables on the battery with your bare hands.