308 gtb alternator | FerrariChat

308 gtb alternator

Discussion in '308/328' started by johnhold, Jan 12, 2022.

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  1. johnhold

    johnhold Rookie

    Jul 5, 2016
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    John
    #1 johnhold, Jan 12, 2022
    Hi all having a bit of a problem my alternator is not charging the battery is their some sort of fuse for the alternator or somat to look for before I have go down the root of trying to get it out cheers
     
  2. Vinsanity

    Vinsanity Karting

    Sep 9, 2013
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    "VD"
    #2 Vinsanity, Jan 12, 2022
    You can check your belt tension. The location of the alternator makes it kind of awkward to apply leverage and get good tension on the belt. I was having charging issues a while back, and they magically went away after I managed to get the belt under proper tension. Worked fine for another year and 1000+ miles before I replaced all the belts during a major service.

    I would say the next culprit would be the voltage regulator/brush. They do wear-out, especially the old ones with moving parts inside. Easy to swap out and not very expensive, but you will have to get the alternator out first. (And then, even worse, re-install it.) I don't think you can change it in-place.

    All that being said, before I did any HARD work, I would just make sure my battery, battery terminals and ground strap were all in good shape. Additionally, if your car has had a battery-cut off switch installed, (many have) take a close look at that.

    Good luck
     
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  3. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
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    Brian Crall
    #3 Rifledriver, Jan 12, 2022
    I have replaced regulators with the alternator in place. Not a bad job if car is on hoist.
     
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  4. Vinsanity

    Vinsanity Karting

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    #4 Vinsanity, Jan 12, 2022
    Ah, lots of jobs are easier with an actual lift. Maybe in my next house.
     
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  5. thorn

    thorn F1 Rookie
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    Aug 7, 2012
    3,322
    Tallahassee, FL
    #5 thorn, Jan 12, 2022
    Is the charging light on? (Either lit on startup, or lit while the car is running, or never)

    Been awhile since I've dealt with the 308 alternator... but it seems like the "charging light" on the dash is wired in series to the (+) terminal, and this 12V source is required to tell the alternator "ok, do your thing." If that circuit isn't complete, I'm not sure the alternator will start charging.

    (My apologies if I'm wrong on this; pls correct my misinfo if appropriate.)
     
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  6. derekw

    derekw Formula 3
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    #6 derekw, Jan 12, 2022
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  7. johnhold

    johnhold Rookie

    Jul 5, 2016
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    #7 johnhold, Jan 18, 2022
     
  8. johnhold

    johnhold Rookie

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    #8 johnhold, Jan 18, 2022
    Hi cheers for all the replys I've checked all ground straps seen to be all good I gather the charging light is the bottom right red one with g written on it that lights up with ignition on but as a dim light when running I've took the voltage regulator off seems like plenty of meat on the bushes but I've reorderd another one just incase .got a green and yellow wire what plugs in at the side of the positive terminal what is this for and where does it go 2 seems to have a feed going to it and is their some sort of fuse what I might be missing outher than that looks like alternator out if the regulator doesent work
     
  9. ragtop1

    ragtop1 F1 Veteran
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    Larry Warren
    #9 ragtop1, Jan 18, 2022
    Check the heavy gauge cable that runs from the alternator to the starter. Mine was rusted at the starter terminal. After cutting off the old connector and refitting clean wire to a new one, all was perfect again. I was chasing my tail on the same problems you are having.
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  10. derekw

    derekw Formula 3
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    #10 derekw, Jan 19, 2022
    Apologies if I'm asking the obvious but have you checked the DC voltage? One or more of the diodes may be bad or the regulator.
     

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