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  1. #1

    Default Charging problem back again

    Ok this is my old post: Original Thread http://www.gmtruckclub.com/forum/sho...ternator-issue

    So tonight on my way home I noticed my light dim a little, so I looked at the volt meter gauge and it was dipping below 14v where it usually sits and when I accelerated more on the freeway it would dim the lights more. I think its a alternator issue, has anyone had this issue before? I think tomorow I am going to pull the alternator out and have it checked at the local parts store.

    Ok so I took truck to the parts store to have the whole system checked and it all checked out ok. I dont know what to do now because after a few hrs I came out of another store hopped in the truck and driving through the parking lot the volt gauge was way under 14v for awhile then it came back up. So now im lost and any advise will be greatly accepted
    Now heres whats happening now and a little video to show. The lights also still dim a little and fluxuate at idle. PLEASE HELP ME


  2. #2

    Default Charging Problems

    Have you looked into the condition of your battery ?

    Another possibility is the battery cables, corrosion at the battery terminal or
    down inside the insulation.
    A loose cable can cause reactions of this type. It makes a high resistance contact
    if it's not tight enough. This applies to both ends of the cable.

    Boneyfingers
    2003 GMC Yukon XL Denali
    1997 Chevy c-3500 CC Dually
    1994 GMC K-1500 Long bed
    1994 Chevy K-5 Blazer

  3. #3
    Jr. Apprentice SkullMountainRider's Avatar
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    Mar 2011
    Location
    British Columbia, Canada
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    Default

    Boneyfingers makes some good points. A few Questions that I have are, do you have after market stereo equipment? What amperage is the alternator?

  4. #4

    Default

    Boneyfingers the battery tested good and I also checked the cables and they seem good there is no corrosion at the terminals. its tight at the battery and at the starter the negatives are tight as well.

    SkullMountainRider there is no aftermarket stereo or anything else to draw current. the replacement alternator is 130amp

  5. #5
    Jr. Apprentice SkullMountainRider's Avatar
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    Mar 2011
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    British Columbia, Canada
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    Default

    Hmm.. A 130 amp should give you more than enough power. I'm wondering if you can test the gauge to see if it's operating properly? Or if there is a corroded wire somewhere that's just hanging on.?

  6. #6

    Default Charging Problems

    Chris, Since al the usual things check out it now has you
    checking the small wiring off the alternator ,, the plastic connector that
    puts the voltage to the field windings can have the pins pushed up and
    you won't be able to see it without examining it.
    Also, an alternator has to have a minimum of 8 volts in the battery to
    activate the field windings. There is no magnetism inside the alternator
    without the 8 volts, they do not have permanent magnets.
    Good Luck,
    Boneyfingers

  7. #7
    Sr. Engineer
    Join Date
    Aug 2009
    Location
    Virginia Beach, VA.
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    Man, that issue looks like a corrosion issue to me
    Make sure Battery terminals and wires are clean.....and that the insulation is not worn down anywhere that would allow for the wire to short on the chasis somewhere.

    Get a digital volt meter as well and start checking your voltage readings across the charging circuit. Maybe then you can see if there is a drop occurring at some point in the circuit.

  8. #8

    Default

    Tonight I will chase down some wires to see what I can find and make sure the grounds are good, also i checked the voltage output at the alternator and it puts out 14.4v and then at the battery it reads 14.0 that was just at idle

  9. #9
    Sr. Engineer
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    Aug 2009
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    Virginia Beach, VA.
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    Default

    Take the same readings w/ the engine rev'd up some.

    A 0.4v drop seems kinds suspicious to me....

  10. #10
    Jr. Apprentice 3e4u's Avatar
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    Jan 2010
    Location
    Colorado Springs, CO
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    11

    Default

    I just got my 99 Suburban back from the shop yesterday for the exact same issue. I asked the guy who fixed it what he did. He said there was a high amount of resistance between the alternator and the battery. This causes the alternator to work harder and then it will "quit" for a bit and then work fine again. i am guessing the problem gets worse the longer you drive.
    So basically he said he cleaned up the connections between the battery and alternator and got the resistance back down to an acceptable level. It would be good for you to have a ohm meter to check out the readings yourself.
    I messed around under the hood on and off for about a month before I gave up and took it in to be fixed. All seems to be good now.
    Hope that helps.
    1995 3500 6-Pack Dually
    1999 1500 Suburban 4x4

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