Low Voltage Battery light on

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Intoodeep713

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2018
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I have a 2018 Ram 1500 Laramie, Crew Cab 4 Full-Size Doors, Four-Wheel Drive, 5.7L V8 Gas

I changed the spark plugs and coils
I changed the fuel injectors
I changed the alternator and belt
I changed the battery
I changed the battery fuse on the positive terminal
I changed the black box on the negative terminal

And after all of that work the low voltage battery light is still on and if anyone can help me with what the problem is I would be so grateful

Thank you
 

BossHogg

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As you likely learned, firing a parts cannon at a problem usually does nothing to fix the issue but is very successful at draining your wallet.

Most of what you changed has nothing to do with a low voltage indicator and a new battery does not mean the battery is good.

I would start by measuring the voltage at the battery (battery posts and battery terminals) while the engine is running. If the voltage is 12.2 or something like that, it would suggest the alternator isn't working. If you measure a voltage around 13.5 or so, then the system is working and you have a battery connection issue or a grounding issue.
 

MDNUSA

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Hello, any updates on this? I've had the same message for two months now.
 

62Blazer

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Hello, any updates on this? I've had the same message for two months now.
The original poster joined this site and made that one post and has not replied back. It's obvious that they just started throwing parts at the vehicle and did absolutely no diagnostic or trouble-shooting work. Most of their parts that got replaced have absolutely nothing to do with the problem described. A few quick and easy checks to get started:
- buy a simple voltmeter
- Check the voltage of the battery with the engine off. Should be around 12.4-12.8 volts for a charged battery.
- Check the voltage at the battery with the engine running. Would expect at least 13.5 volts or higher.
- Check the battery terminals to make sure they are tight and have not signs of corrosion (white or green crusties).
Come back with your answers to the above and we can go from their.
 

MDNUSA

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Blazer thanks for your response. I only have an older cheap analog meter but it shows 12ish volts not running and 14ish running. Lights been on for a couple months now, I swapped the battery voltage sensor on the negative terminal with a known good one and no change. Gave up after that because unlike the first dude I didn’t want to throw money at it. I thought I read somewhere the pcm regulates voltage and that was another guys problem but I can’t find that post now. It starts fine, runs fine, just having that message and the battery light is annoying is hell!!
 

MDNUSA

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The original poster joined this site and made that one post and has not replied back. It's obvious that they just started throwing parts at the vehicle and did absolutely no diagnostic or trouble-shooting work. Most of their parts that got replaced have absolutely nothing to do with the problem described. A few quick and easy checks to get started:
- buy a simple voltmeter
- Check the voltage of the battery with the engine off. Should be around 12.4-12.8 volts for a charged battery.
- Check the voltage at the battery with the engine running. Would expect at least 13.5 volts or higher.
- Check the battery terminals to make sure they are tight and have not signs of corrosion (white or green crusties).
Come back with your answers to the above and we can go from their.
Blazer thanks for your response. I only have an older cheap analog meter but it shows 12ish volts not running and 14ish running. Lights been on for a couple months now, I swapped the battery voltage sensor on the negative terminal with a known good one and no change. Gave up after that because unlike the first dude I didn’t want to throw money at it. I thought I read somewhere the pcm regulates voltage and that was another guys problem but I can’t find that post now. It starts fine, runs fine, just having that message and the battery light is annoying is hell!!
 

craigweiler

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Rainier, Oregon
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2016
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5.7
So a few months ago the battery in my 2016 Ram 1500 5.7 finally died and I replaced it with a new Napa Premium. Everything has been fine until a few weeks ago. In the mornings on start up I was getting Low Battery Voltage and the battery symbol would lite up. If I turned the truck off and restarted, it would go away and I'd be on my way. The other day it happened and it stayed on. I used AlfaOBD to clear the code & started reading threads on here about similar issues. I have tested the battery with the HFT load tester and all is good (1000cca). With a multi meter the battery is 12.6 not running & 11.8 - 12.3 for a few minutes and then it jumps to 14.8 and stays there. Start up the next day and it's the same thing over again. I'm at my witts end trying to figure this out. HELP
 

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