HELP, battery charge light won't go away!
01-14-2009, 10:09 PM
#1
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HELP, battery charge light won't go away!
Ok, a couple months ago I was on a trip in my 1999 F-150 4.6L V8. Several hours into the trip the red battery light came on, the volt meter read normally. I looked in the manual and all it said was the light indicates the battery is not charging properly. I pulled off the interstate, and on the off ramp the light went out. We stopped for food, and while in the drive through lane the light came back on. I pulled into a parking spot and restarted the truck, and the light went out.
About an hour down the road, the light came back on. I kept driving for awhile to see what happened. The volt meter started to drop further and further as I drove. As it neared the low position, I pulled off again, got gas, and waited to see what would happen. Eventually the lights, radio, and dash all started to shut down. And then the truck finally died. The next morning I replaced the alternator, almost certain that it was the problem. For the remainder of the trip the battery light remained off.
A week or so later the light started flickering on and off again. Thinking the battery may have gotten damaged in the first ordeal, I went and had it checked. It did show low output, and the store replaced it since it was still under warranty. The light went out again, but just an hour or so later it came back on. Here is what is baffling, while the light is on I checked the volts, 14.8v, then shut the car off and it drops to 13v. That would lead me to believe that even when the battery light is on, the alternator is providing adequate power to charge the battery and run the truck. Now, at no time does the volt meter drop off from when the light is on and when it is off.
I am at a loss as to what is causing this light to come on and off when it seems that the alternator is doing it's job, and the battery is brand new. Does anyone have any clue what is going on with this thing?
About an hour down the road, the light came back on. I kept driving for awhile to see what happened. The volt meter started to drop further and further as I drove. As it neared the low position, I pulled off again, got gas, and waited to see what would happen. Eventually the lights, radio, and dash all started to shut down. And then the truck finally died. The next morning I replaced the alternator, almost certain that it was the problem. For the remainder of the trip the battery light remained off.
A week or so later the light started flickering on and off again. Thinking the battery may have gotten damaged in the first ordeal, I went and had it checked. It did show low output, and the store replaced it since it was still under warranty. The light went out again, but just an hour or so later it came back on. Here is what is baffling, while the light is on I checked the volts, 14.8v, then shut the car off and it drops to 13v. That would lead me to believe that even when the battery light is on, the alternator is providing adequate power to charge the battery and run the truck. Now, at no time does the volt meter drop off from when the light is on and when it is off.
I am at a loss as to what is causing this light to come on and off when it seems that the alternator is doing it's job, and the battery is brand new. Does anyone have any clue what is going on with this thing?
01-15-2009, 03:00 PM
#2
Senior Member
Welcome to the forum Eric. Your problem is interesting and your knowledge of the system is greater than most. Just looked at my 02 alt diagram and its different then I have encountered. Go to this site, it might help you.
Go to: search.ebscohost.com
USER: greatfalls
PASS: publiclibrary
Select auto repair, year, make ect..
Good luck!
Go to: search.ebscohost.com
USER: greatfalls
PASS: publiclibrary
Select auto repair, year, make ect..
Good luck!
01-15-2009, 03:13 PM
#3
Senior Member
I guess that there's a loose connection somewhere... Generally alternator lamp controller monitors voltage regulator output (one which manages alternator output voltage) and alternator output voltages. If either of them is 0, it turns in the lamp, if i know it right. Since your charging system seemes to be working, i think that the problem is in the lamp circuit.