Ford Super Duty (1999-2016) :: Battery Light On But Alternator Is Charging?
Jan 24, 2010
OK I have 14.04 volts at the batteries with the engine running but my battery light is on. I had the alternator checked off the engine and on the engine and it tests good. Shows good batteries and good charging. Is there something internal to the alternator that would make the light come on even though the alternator is charging ok? Or is there something else that would make the light come on. This is on a 1999 F250 Superduty Powerstroke 7.3.
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My alternator quit charging last night. Was pretty much a sudden onset as I was driving down the road and left off the accelerator the battery light came on and lights dimmed a bit. When I stepped on the accelerator again they bat. light went off and the lights came back up.
At idle I'm at 11.77v. I've pulled the plug on the back of the alternator and I'm getting voltage on both the red and green wires that go into the plug with the engine running. Is this correct?
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Pretty much as the title says, I'm having an interesting electrical gremlin. Ford 7.3 super crew 2002 lariat LE.
I have batteries from 2015 that are losing their charge, both of them. It's like the alternator isn't charging them. Truck will struggle to start until jump started, then she's fine.
Symptoms are:
ABS light comes on when as best I can tell the batteries aren't getting charged. Not the battery indicator.
Now that the batteries are low enough, on the instrument cluster the little light the powers the mile LCD screen dims when it's not getting power (but it's fine when the batteries have charge.)
All accessories work when driving, but I haven't been able to drive a long while on the "not charging phase" to see how low they're go.
Batteries register dead (now) because they haven't gotten charge in a while.
When the alternator IS charging or "connected" I can leave the truck idle and she'll charge the batteries, truck will start just fine on the next run (no parasitic drain.)
Driving causes this to happen randomly, doesn't happen when I'm stationary, nor do I believe it CHANGES state (so if I'm idle it won't suddenly NOT charge if it was charging before.)
Narrowed down to 2 probable things.
Alternator
Bad alternator to battery cables
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for some reason my battery light flickers when im driving regular and on the highway. I have had both batteries checked and they were at 50 percent charge and both were good so therefore I assumed it was my alternator. I removed alternator had it check and it passed all test. Everything was checked at o'reilly and autozone
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I had to replace my alternator (single unit) and after installation it seems only 1 of the 2 batteries is charging when I check them while the truck is running. What check or could be the problem?
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Took in the alternator to get it checked and they said it was good. Put it back on and it seemed like it was charging according to my volt meter (14.24-13.5 v)
Today, it's not charging. Only reads 12.2 v while running. Is there a fuse or something I need to check? Grounds? It seems intermittent.
2003 F-250 V10 6.8 liter 255,000 miles.
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I have a 2000 excursion that stopped charging. The battery light is on . I replaced the alternator but it still will not charge. I have checked all the fuses. Not sure where to go from here...
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2002 f350 super cab 7.3 diesel, replaced alternator because wasn't getting charge to batts, Napa guy checked batts and determined no charge, replaced alt, still no charge, have 12v at alt post with engine running or not. My ? is, is there a fuse in here somewhere that I'm missing? Went through all fuses in fuse panel all good.
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I put an O'reileys alternator in my truck today. Drove it most the day and did some plowing with it and it was fine. I just went out to run to the gas station and now the battery light is on. The voltage is still good.
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I have a 1999 f-350 V-10. My battery light came on, making me believe that my alt. has quit. I can't see the plaque on the alt so I can't tell the amps. Does my serial number on the truck tell the amps, or do i have to remove the alt to check the amps?
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I replaced my alt. because in the morning the bearing would squeak and the head lights flicker. It was a life time alt. Put the new one in now it wont charge. Took it back and got another, same thing. Also replaced the starter relay and battery. I checked the fusible links and replaced a terminal connector. The wires look good. There is 12v on the alt lug and pins 1 and 3 on the connector with the key off. Turn key on and 12v disappears form pins 1 & 3. Also checked all fuses in both boxes. I ohmed out the wire harness from the alt back to the connectors, all good. What am I missing? This is a 99 f530 5.4l.
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I went to start my 2006 F350 6.0 this morning. 20 degrees outside. It nearly turned over, then it appeared that the batteries would not support another start - a slowing of the pre-engine start revving....
So I let it sit a while, now it won't start at all. When I try to start it, the dashboard flashes, clicking sounds occur and even after pulling out the keys, the needles on the gauges shake for a few seconds.
Is this more a battery issue or an alternator issue?
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My trouble is that the alternator light on my 2004 F-250 Diesel began to come on occasionally, but never constant. Taking in the fact that it was still the original alternator, and over 70,000 miles, I figured it was time for a new one. I installed the new one and after two days the light came on again. I tested the alternator and it read 13.84 volts while running. With the engine shut off, I had 12.59, and 12.6 volts at the batteries. What may be my problem? Diesel down.
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My 05 F20 CC LB 6.0 4WD has the alternator light on for a few miles then goes out also sometimes goes away when you accelerate hard, is my alternator going, or is this some common glitch in the light hopefully?? Also every once in a while got the death wobble, installed tie rod ends and center link, but if I hit a bump just right it does it.
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So my truck drove great to ocean city MD this weekend. Power is perfect again, feels really tight. But now I have having to additional problems.
1) My alt light had been flickering a couples times a month. Last night it came on and stayed on. Lots of threads about this I Know!
I am hoping that cleaning and tightening the connections will do the trick since the alt is a Bosch with only 25k miles or so. But I want to order a rebuild kit:
is my alt a 3G or a 3G8429?
F SERIES | Alternator Starter Rebuild Kits
2) I started to have a ticking at idle. Its very regular and sounds like its coming from the passenger side valve cover. In random threads I have read about timing chain guides breaking and loose rocker arms.
Most of the time its 3 ticks in a row and then a pause. Should I be pulling the valve cover? Think I need to R&R the timing chain? I will post a video later!
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We've got a 2012 F550 6.7 with 138k. It recently got a battery light. The batteries are right around 12 volts with the truck running or off. I also tested the output on the alternator and its not charging. I put a new alternator in it and still no charge. All the connections are tight and clean. The batteries load test ok. Where to look next?
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Battery symbol light appeared on dash, After determining battery was good, I removed alternator and took it to have it bench tested at the parts store. It tested bad so I purchased a rebuilt alternator and had it bench tested before I left the store and it tested good. I installed it and it won't charge the battery. Tried a new battery...same thing. I tested the voltage at the battery and it reads 12.3 and the same with engine running. Engine runs until battery is drained. I removed the alternator and took it to a different store and they bench tested it good also!
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I've got a '03 F250 7.3L 4x4 (not sure how much info you need) with many many miles. My battery light came on a couple of months ago. Replaced a battery. Light went out for a day. Checked and replaced the alternator. Light went out for a couple days. Cleaned the battery terminals for better connection. The battery light is off when I first start the truck, but depending on what I've got turned on, lights, radio, AC, the battery light comes on with in 15 to 30 miles down the road. I had the batteries and the alternator rechecked yesterday and everything seems to be charged and charging.
- Should I replace the wiring to the alternator?
- Are there any fuses I should be looking at or for?
- The alternator is a rebuilt one from Autozone, should I get a new one?
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Battery light came on today, I figured were in need of replacement so I got new ones. Light is still on, until I reach about 1800 rpm. It goes out until truck idles down. Can an alternator do this? I always thought when they went, they went.
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The battery light is on when running. The light is dim at idle. Light is bright when driving with rpm's. The battery voltage is 12.8 per my older volt gauge. Alternator out put is 14 volts at idle and with rpm (2,000) +. I had the Alternator checked at AutoZone in there parking lot. Meter hooked up. The alternator passed all test.
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The manual just says it's a charging system problem.
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