Lights dim at idle, bad alternator?

Posted by steelgrave, Feb 17, 2003
Newbie Forum - Beginner/newbie/general DSM modification questions. First mods, how to run 10's when you haven't run 12's yet, any tech question that doesn't fit in another tech forum.

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  1. steelgrave

    steelgrave Proven Member

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    burnsville, Burnsville_MN
    I have a 98 GST and the original Battery finally bit the dust a couple months ago (after a few jumpstarts). Replaced it with a nice new one, and now I've noticed that when idling, the lights seem to dim a bit. I'm guessing the alternator is about to die. Anybody know how much a new one costs compared to a rebuilt and if a rebuilt is even worth it? How about an aftermarket?

    Any help would be great...

    Steelgrave
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  2. 95mitsugsx

    95mitsugsx Proven Member

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    , Andover_MN
    Dimming lights at lower RPM usually signify a bad alternator. Don't know about the replacement though.
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  3. KRAZYKOREAN

    KRAZYKOREAN Proven Member

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    Phompton, Arizona


    Go get it checked at like Autozone etc. and they will let you know, it does sound like the voltage regulator is bad. So get it checked:thumb:
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  4. 95mitsugsx

    95mitsugsx Proven Member

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    , Andover_MN
    My 95 GSX does the same thing, kind of annoying, but it always starts strong even in this cold ass minnesota weather.
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  5. ltvarney

    ltvarney Proven Member

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    Both my 1g's have dim lights at idle. I've been repeatedly told that it's normal until you rev it up. When driving there's no problems.
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  6. KRAZYKOREAN

    KRAZYKOREAN Proven Member

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    Phompton, Arizona
    But also I would check just incase, because when your volateg regulator is bad on the alternator it does the same thing, but then after a little bit it starts to over charge your battery and then your battery just takes a sh$t. my optima battyer pretty much exploded. Well not exploded but yeah. I would just check, for mine sake.:thumb:
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  7. rubbersidedown

    rubbersidedown Proven Member

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    , ohio
    I had the EXACT same problem. It turned out one of the battery cables came loose on the terminal. It was still connected but for some reason it wasn't a "complete" connection or something. Trying tightening the cables on your terminals and for anyone w/ an older battery its a good idea to clean the terminals while you're at it. I know it sounds like i'm full of crap but at least give it a try. it worked for me and saved me having to buy another battery.
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  8. sho_pow

    sho_pow Proven Member

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    Gilbert, Arizona
    I had a similar problem, but it was after I replaced my alternator (rebuilt). My ground wire to the alternator wasn't tight so I wasn't properly grounding. You should check that also just in case.
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  9. m_eclipse_96

    m_eclipse_96 Proven Member

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    ottawa, Illinois
    hold on a sec, how can u people sit here and say its the alternator, the alternator is what charges the battery, if your just idling then the alternator hasnt kicked in yet, and then the battery would be just running on its own, the alternator dosnt kick in till about 2000rpm. i would say that if ur lights are diming when idling then u bought a bad battery, u must have a waranty on that battery so take it back and get it replaced.
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  10. InferiorWang

    InferiorWang Proven Member

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    but if the alternator is bad then it isnt charging the battery so when the lights just run off of the battery it gets less juice than it should.

    im guessing alternator. You can try tightening you cables and see how that helps. Clean the corrosion of first if you have any (baking soda and water work wonders)
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  11. m_eclipse_96

    m_eclipse_96 Proven Member

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    ottawa, Illinois
    im guessing alternator. You can try tightening you cables and see how that helps. Clean the corrosion of first if you have any (baking soda and water work wonders) [/B][/QUOTE]

    the lights only dim when its idling, so when he gets going and hits about 2000rpm the alternator will kick in and then it wont be just running off the battery, geezz

    forget it if u wanna think its the alternator go ahead i told u what i thought.............. peace
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  12. 961

    961 Probationary Member

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    Edmonton, Alberta_Canada
    Normal alternators (on "newer" vehicle that has at least EFI) like on a toyota, have a voltage regulator, and as soon as the voltage drops the alternator will kick in, and has nothing to do with the RPM's. On a older vehicle the alternator will just run all the time.
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  13. AlphaAssault

    AlphaAssault Proven Member

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    Tyler, Texas
    nice gravedigging!
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  14. Defiant

    Defiant DSM Wiseman

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    glorious Galt, California
    Halloween or not, you dug me up for that?

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