Battery light on
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New User
Joined: Feb 2020
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From: Fairfax ok
Battery light on
2011 F250 4x4 6.2 flex fuel 4 door Truck died yesterday with battery light on.....replaced battery in a panic as I was 90 minutes from home hardly any tools on hand....it got me home and died in the driveway....put new tested alternator on....start perfect....alternator is charging at 13.6 volts....all fuses good....battery checks at 13.6 while running also....turned on all accessories .....bright lights....radio...AC....everything possible to drain the battery and everything tests good....still have the light....truck is showing no codes but my reader is super old....this is my only vehicle I'm scared to go to far...any help is greatly appreciated....once its figured out I wont leave the thread hanging ill post the fix....thank you to anyone that can help .....Semper Fi.....
edited:::when I turn the truck off and restart it the battery light is not there for at least 45 seconds after starting .....also I can clear the light with my scanner and it comes back in about 45 seconds.....during those times the alternator is still charging correctly
edited:::when I turn the truck off and restart it the battery light is not there for at least 45 seconds after starting .....also I can clear the light with my scanner and it comes back in about 45 seconds.....during those times the alternator is still charging correctly
Last edited by ShannonKincaid; Feb 15, 2020 at 02:57 PM. Reason: Vehicle info
Lead Driver
Joined: May 2003
Posts: 9,303
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From: Lyndonville, Vermont
The red light you can clear with the scanner??? I doubt it... or check engine light.....2011 yea now I see
fully charged battery will show 14.4 or so with truck running.
Low battery could see 13.5 and up till charged..
fully charged battery will show 14.4 or so with truck running.
Low battery could see 13.5 and up till charged..
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From: Fairfax ok
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From: Fairfax ok
Napa guy recommendation
The guy that ran the tests said the alternator was charging but not enough.....it was charging at just under 13 volts.....he said exchange the alt I just bought for another new one.....I'll be honest I have no clue what all this means I'm just regurgitating information here... Thank you guys for everything
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From: Fairfax ok
Battery voltage
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New User
Joined: Feb 2020
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From: Fairfax ok
New alternator
No change with new alternator....will look at checking wires to PCM.....not sure what to do at this point this truck has been really solid and good to go for a very long time ......
Lead Driver
Joined: Mar 2010
Posts: 5,504
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From: Woodbridge, Ontario, CA
What kind of vehicle are we working on? I mean year, make, model and engine. It does help to include this information when requesting diagnostic assistance. FYI a battery light remaining on doesn't necessarily mean the alternator is the faulty component.
More Turbo
Joined: Dec 2015
Posts: 500
Likes: 38
From: Pacific Northwest
You own a test light? Or Volt meter?
This is very simple, you need to check for battery drain when it’s off. Something may be grounding out somewhere and leaching off a lot of the power to ground.
Disconnect the battery’s negative battery terminal and put your volt meter between the two. One on the battery side negative terminal and one of the trucks now disconnected negative terminal. You should see 0.0 or close to it. If it’s anything higher you now have to start pulling fuses to see which one is the problem.
Also an alternator can slowly die. One of the three leg diodes might stop working causing it to run fine but seem like your battery is dying, because it’s not being charged back up after starting. But your alternator test should of indicated a bad alternator if this was the case.
Good luck! You’ll figure it out.
This is very simple, you need to check for battery drain when it’s off. Something may be grounding out somewhere and leaching off a lot of the power to ground.
Disconnect the battery’s negative battery terminal and put your volt meter between the two. One on the battery side negative terminal and one of the trucks now disconnected negative terminal. You should see 0.0 or close to it. If it’s anything higher you now have to start pulling fuses to see which one is the problem.
Also an alternator can slowly die. One of the three leg diodes might stop working causing it to run fine but seem like your battery is dying, because it’s not being charged back up after starting. But your alternator test should of indicated a bad alternator if this was the case.
Good luck! You’ll figure it out.