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Thread: Voltage Regulation Issues

  1. Top Of Page | #1

    Voltage Regulation Issues

    Hello everyone,

    About two nights ago the battery light came on in my truck (2014 2500 cummins).

    The voltage read-out on the dash was 11v. The RaceME tuner was reading 0.98v.

    Made it home, and the next morning I checked the DTC's in the RaceME, and it had P063C: Generator Voltage Sense Low, P063D: Generator Voltage Sense High, and P065A: Generator System Performance.

    I hooked up the battery tester, and it read 12v on both batteries, but wouldn't read a load test or the alternator (said battery charge too low).

    The volt meter was reading 11.5v and 3.6v ripple.

    Sooo, I'm assuming it's an alternator issue, because I assumed the voltage regulator was internal to the alternator on this truck.

    Replaced the alternator this morning and checked the RaceME and it was reading 13.5-14.5v.

    Put everything back together, and checked the RaceME again, and it was reading 0.73v!

    After reading a few other posts I found that the voltage regulator is actually part of the PCM, now my question is, is my tuner programming screwing with the voltage readings?

    I wiped the ECM tuning back to stock, and no change, then re-loaded the custom tunes, still reading low voltage.

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  2. Top Of Page | #2
    More Powa! RATLIN'HP's Avatar

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    Voltage Regulation Issues

    Check and clean battery connections and grounds.

    Sent from my SM-A505U using Tapatalk

    2015 Black Laramie CCSB 3500 SRW. Thuren Leveled With Fox 2.0 Shocks. Ride Rite Rear Air Bags With Wireless Airlift Onboard Air. 35" Toyos. All The Options Minus The Soot Cookers. RaceMe Ultra.

  3. Top Of Page | #3
    More Powa! RATLIN'HP's Avatar

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    Voltage Regulation Issues

    Could be batteries also.

    Sent from my SM-A505U using Tapatalk

    2015 Black Laramie CCSB 3500 SRW. Thuren Leveled With Fox 2.0 Shocks. Ride Rite Rear Air Bags With Wireless Airlift Onboard Air. 35" Toyos. All The Options Minus The Soot Cookers. RaceMe Ultra.

  4. Top Of Page | #4

    Voltage Regulation Issues

    Quote Originally Posted by RATLIN'HP View Post
    Check and clean battery connections and grounds.

    Sent from my SM-A505U using Tapatalk
    Sorry, should have included: new batteries and clean connections.


  5. Top Of Page | #5
    More Powa! RATLIN'HP's Avatar

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    Voltage Regulation Issues

    Quote Originally Posted by Woodlark View Post
    Sorry, should have included: new batteries and clean connections.
    If it's not a bad battery, it could be a number of positive connections from the alternator to the PCM, or frame ground, body grounds, so on.

    Usual culprits are batteries, and or battery connections.

    Sent from my SM-A505U using Tapatalk

    2015 Black Laramie CCSB 3500 SRW. Thuren Leveled With Fox 2.0 Shocks. Ride Rite Rear Air Bags With Wireless Airlift Onboard Air. 35" Toyos. All The Options Minus The Soot Cookers. RaceMe Ultra.

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  7. Top Of Page | #6

    Re: Voltage Regulation Issues

    OK, so I found that the hot lead from the alternator to the passenger side battery had rubbed against the turbo housing and was shorting.

    Repaired and re-routed the wire, let it idle for about 10 minutes, and the voltage on the tuner (which measures alternator output) was steady at 14.5v.

    Got in and started driving, at about a half mile form home, the voltage dropped to 7.5v, and started slowly, but steadily dropping off to 3.8v.

    Came back, shut the truck off, removed the intake to access the alternator, started the truck and measured the voltage at the post on the alternator: 14.5v.

    Looked at the tuner; 14.5v. WTF!?

    Got in, started driving and made it about 50 yds and the voltage dropped to 1.8v.

    Got out and measured it at the alternator post; 1.8v. Brand new (not rebuilt), Duralast Gold alternator.

    On my way to Autozone right now, I'll pull the alternator and put it on the tester there and see what it say's.


  8. Top Of Page | #7
    More Powa! RATLIN'HP's Avatar

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    Re: Voltage Regulation Issues

    Load test the new batteries also.

    Make sure your belt is ok and not slipping as well.

    Sent from my SM-A505U using Tapatalk

    2015 Black Laramie CCSB 3500 SRW. Thuren Leveled With Fox 2.0 Shocks. Ride Rite Rear Air Bags With Wireless Airlift Onboard Air. 35" Toyos. All The Options Minus The Soot Cookers. RaceMe Ultra.

  9. Top Of Page | #8
    VENDOR cumminsdieselfreak's Avatar

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    Re: Voltage Regulation Issues

    Quote Originally Posted by Woodlark View Post
    OK, so I found that the hot lead from the alternator to the passenger side battery had rubbed against the turbo housing and was shorting.

    Repaired and re-routed the wire, let it idle for about 10 minutes, and the voltage on the tuner (which measures alternator output) was steady at 14.5v.

    Got in and started driving, at about a half mile form home, the voltage dropped to 7.5v, and started slowly, but steadily dropping off to 3.8v.

    Came back, shut the truck off, removed the intake to access the alternator, started the truck and measured the voltage at the post on the alternator: 14.5v.

    Looked at the tuner; 14.5v. WTF!?

    Got in, started driving and made it about 50 yds and the voltage dropped to 1.8v.

    Got out and measured it at the alternator post; 1.8v. Brand new (not rebuilt), Duralast Gold alternator.

    On my way to Autozone right now, I'll pull the alternator and put it on the tester there and see what it say's.
    Did you load test the new batteries individually? New batteries doesn't mean healthy batteries. Also, did you buy a Brand New alternator or a Reman? I always recommend buying a Factory NEW alternator.

    2018 Ram 2500 4x4 G56
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  10. Top Of Page | #9

    Re: Voltage Regulation Issues

    So, after testing the continuity of all wires between the batteries, and the grounds, and individually load testing the batteries I found the problem.

    I did not realize the connecting posts on the batteries are actually fuses, feel a bit stupid for not noticing earlier.

    Apparently, when the old alternator went out, it must have sent a spike and blew out the fuse where the alternator connects to the passenger side battery.

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