Battery Light Slightly Flickering??????

[DieselFam]

Wife called yesterday and said the battery light in the excursion was slightly flickering as she drove down the road. It started in the morning with no problems and drove fine. I drove it when she got home and noticed the same thing. It flickers whether I was hard on acceleration or driving normally. Only when i was completely off the accelerator did it not flicker. It also flickerd when I put the brakes on. The alternator went bad and ruined my batteries in May of 2009. I replaced the whole set up at that time. Checked batteries and they are full. Any ideas before I take it in? Thanks

[seawolfbronco]

Most likely a bad alternator. You should check the wiring to the field, but most likely is a bad diode in the internal regulator of the alternator. It's probably still charging a little, but the voltage is down, especially at low RPMs.

[DieselFam]

Thanks Seawolf. I better get it off and have it checked. I had heard that you shouldn't have Autozone or Kragen do alternator tests because they only read if its really dead???? Have you heard this?

[terryknight]

check to make sure all the wires going to the alt are tight

I had one flickering on a trip to and from MA and i found that I had a loose wire

[seawolfbronco]

Well, considering the caliper of help in those places....they're not techs, just clerks, really. If you have a volt meter, just check the voltage. It should be putting out better than 13.5v at idle, if your batteries are fully charged (>12.5v key off). My Ex was doing the same thing. The batteries would not go fully dead, but the Alt light started to flicker. I had noticed that voltage at idle was low.

[DieselFam]

Thanks all. I will check tonight when I get home and post the results. I hope its just a loose wire. That alternator is only 20 months old.

[DieselFam]

No loose wires, so I guess I will pull the alternator and have it tested.

[terryknight]

well that's too bad. hopefully it's under warranty

[DieselFam]

So after checking for loose wires, which there weren't any, the light quit flickering. So I checked the plug in wires. All looked good. The light stayed out until today while on a 2 hour drive, when it started flickering lightly again. I checked the wires. All were still good. One thing I noticed was under hard acceleration the light was brightest and stayed on. If I were just cruising along it was a very dim flickering light. If I were coasting it was off. I am definetley taking for a test tomorrow. It is very puzzling though. Any ideas? In the past on different vehicles when that battery light comes on it stays on, bright. Belts are tight and battery cables are as well. If I have to get a new alternator, I would like to buy an American one, or at least North American one. Does anyone know of one made here. My local NAPA auto parts store only has chinese stuff. O'Reilly the same. I can't find any "made in" information for Motorcraft. So I would assume they aren't. That is usually big bragging rights if its made in America.

[terryknight]

i like Bosch, but that's me. always had good luck, and i have no clue where they are actually made