Battery Light On/Off

[JBoRacer]

Hi everyone, I discovered your site while I was trying to solve a Battery Light issue on my 2005 Expedition. My battery light came on and would go off if I accelerated or if I reved up the engine...sometimes. Not long after it would go out it would come back on. I was driving it home and noticed my battery gauge was dropping fast. By the time I got home it was at its lowest point and several other lights had illuminated on the dash(Air Bag, ABS). I shut the vehicle off and it would not start...dead battery! I assumed the alternator was bad so I took it off and headed to AutoZone. They tested the Alternator several times and it showed to be good. I then brought my battery to them, they gave it a charge, load tested it and said my battery was fine. I then looked at my owners manual and located any fuses that could be bad. Still didn't fix the problem. I then checked some of the wiring to see if there was any loose wires or bad connections and cleaned my battery cables, still didn't fix the problem! I then charged my battery up again and drove my Expedition to AutoZone and had them check my alternator while the vehicle was running...BAD Voltage Regulator which is internal on the alternator. I got a new alternator and the problem was solved! I hope this post helps someone else that may be having this same issue fix your vehicle with a lot less frustration then I faced!

 

[Bedrck47]

shame you had to get an alternator as you could have just replaced the regulator
easy fix if your handy

 

[Doctor Dirt]

Wait a minute! I just went thorugh similar experience and checked out all wires and fuses before pulling alternator and going to the store to test. I noted that the bench test included a test of the regulator. The VR is external (on the back of the alternator) on my 97. Am I hearing that the auto store load test does not actually test VR even though it appears to? I was resigned to another hour or two of tuggin wires and poking around with the VOM in hopes of finding the problem. But i think i just read that the bench test is unreliable and it needs to be tested under load. The Haynes book seeems to tell me to test it in place. But tHose test points are hard to reach while on the vehicle. Any help would be appreciated.