ParacordHut

So, here's the story......truck was running fine, went fishing and when I got back in truck to leave, it fired right up but I noticed the battery light was on.....as I drove it, the battery light would go off and come on and go off and come on. It went on like this for about 4 miles, then all of my gauges went to down to nothing and lights went very dim. I pulled over and had a buddy of mine come and jump me off.....made it a mile or 2 and then did the same thing. We exchanged batteries to get me home. Today, I purchased an alternator and put it on and the truck fired right up but the battery light was on, but this time it wasn't going off and on, it just stays on. So, I went to Advance Auto, had them check the battery and they said bad battery, so I figured I probably killed a cell in the battery, so I bought a new battery. So, now truck has new alternator and battery BUT battery light is still staying on. I had them check both and they said, new battery and alt showing good. I know all of the connections are tight and I checked the fuses inside the truck and all are good. I'm wondering if this is a case of the light maybe going out by itself, after being driven a while, like the CEL light or if I have another problem? Please help. Any advice is appreciated.

Thanks!

digitaltrucker

Ford alt or third party?

BrittonN

Broken wire coming off the alternator. It may not look broken but it could be broke inside the insulation. That was the story with my 4.6L. The battery light would come on and off, wiggled the single grey wire and it would turn the light on and off.

ParacordHut

remanufactured alt....

mbb

unfortunately, alternators can be problematic in the exact way you see.

Buddy of mine replaced alternator in his crown vic once, I helped.
Autozone alternators. He tried 4 different alternators before finding one that actually fit, and the batt light went off. Some simply werent really compatible.

I had issues with Isuzu Trooper alternator once. The computer control , which controlled everything on engine and tranny, was very sensitive to precise voltage. Nothing but factory alternator worked right, engine would die going down road, and then restart...sometimes. I tried several aftermarket before giving up and getting factory..

blupupher

iTrader: (2)

Has the battery been fully charged from a slow trickle charger? An alternator can have a hard time charging an almost dead battery (and a new battery can be almost dead sitting on the shelf).
Also, as others have said, bad wiring can cause all kinds of bad issues.
And finally the alternator, new or reman, Motorcraft or other? Reman on these trucks just don't seem to cut it. Some also have issues with new alternators other than Motorcraft.
I chanced it when I needed a new alternator, I got a new alternator from Advance Auto, their Carquest 130 amp one, and it is working fine so far, but has a lifetime warranty.


One thing when testing alternators is many times they will test fine for the short test when cold on the test bench, but when hot they won't charge worth a darn. Had a house brand reman I bought for my old car from Advance Auto. It tested good in the store before I left with it, went home, installed it (on a vehicle with a charged battery). It tested fine, putting out 14.2-14.4v. Drove to work the next morning, windows are going up slow again, lights seem a little dim. Plugged in my volt meter, only 12.3 v with the engine running. Come back out that evening, 14.2v again. Did this off and on for a week. Took the alternator out and had it re-tested, passed. Put it back in. Kept doing same thing. Replaced battery (under warranty, appeared to have one cell bad) but still doing it. Drove to the parts store, pulled the alternator out in the parking lot (could do it in about 5 minutes by now) and brought it in and tested it while hot, it failed. Got another reman (no cost to me) and it say good on the test bench, install it, and in a week doing it AGAIN. Drove it to the store and took it off and again tests bad. Manager (who knows I do a lot of business there) just said take a new one. No problems with it for 2 years till I sold it.

w0lvez

Remove the corrosion on the Alternator Wire Terminal. If Corrosion have damaged the wire terminal eyelet replace the wiring harness. Check the Alternator Stud, NUT and Cable Terminal if they are made of same metal (Steel, Brass or Copper). If they are made of dissimilar metal galvanic corrosion will occur causing poor metal to metal contact. Electric Terminal Grease can be use to reduce the possibility of corrosion.

jstockert

Someone needs to contact w0lvez, I think soneone has hacked his account. This post actually has useful and meaningful info.

questionboy

Reviving an old thread to share my recent experience with a remanufactured alternator from Napa Auto Parts:

1999 F150, 120k mi, 4.6L

My battery light had been on intermittently for a couple days, I ignored it because the needle on the gauge remained in the same place as it always is. Of course it finally died altogether while driving, windshield wipers slowed way down, started running rough just before it died, and I knew right away it was a charging issue. I checked the fuses, fuseable links, cleaned terminals, checked the serpentine belt, then pulled the alternator. I removed the regulator/brush assembly to find one brush worn all the way down, and a blackened and scored slip ring. No need to bench test that.

Bought a remanufactured alternator from Napa, installed it and found it to be charging fine (14.3V), but the battery light on the dash stayed on. I removed the connectors on the alternator for inspection, checked continuity on the green single jumper from the alternator back to the three terminal connector and then back to the connector near the solenoid, it all looked good (this circuit controls battery light illumination by comparing battery voltage with alt output voltage, I think). I pulled the alternator back off, and while inspecting the single terminal on the alternator, and noticed black paint overspray from the rebuild process inside the connector. Closer inspection with a magnifying glass showed overspray covering the terminal itself. Of course I could have cleaned it off and it would have been fine, but ****, I was irritated. I went back to Napa and showed them the problem. We checked the other remanufacured unit they had in stock, it was the same, overspray covering the terminal. We checked the terminal on a brand new unit, of course it was clean, so I bought it. Installed the new unit, charges fine, no battery light, problem solved.

My takeaway from this: The battery gauge is useless as a charging system warning, pay attention to the battery light. I initially saved about $30 buying the remanufactured vs new, then spent an another 3 hours with further diagnosis/R&R/additional trips to fix the problem. Nothing more irritating than having to get towed home, diagnose a problem, then buy and install a part that comes with a new and different but associated problem...

QB

Jbrew

That will kill it... without a doubt!