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Electrical Problem GT4

Discussion in 'Technical Q&A' started by Mark 308 gt4, Mar 21, 2009.

  1. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    I have a charging problem on my Gt4 and it has me beat.

    If I warm the car up and drive out, after 1/2 an hour the alternator light comes on. If I then switch off for a short while it will go out again on start up, drive off down the road and once again the lamp comes on. Blip the throttle and it seems to try and go out. I have taken the alternator out and had it professionally tested and all is good. I then set up a small test of my own to double check and it seems fine, so I changed the regulator just for the sake of it.
    Placed it back on the car, went for a test drive in the dark, full lights on. I thought all was fine but 1/2 hour later, on it came again.


    Does anybody out there have a clue what it could be, maybe point me to an earth I am missing, anything would be helpfull.

    Many thanks in advance

    Mark...
     
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  3. parkerfe

    parkerfe F1 World Champ

    Sep 4, 2001
    12,887
    Cumming, Georgia
    Full Name:
    Franklin E. Parker
    Take it to an Autozone and they will hook it up to an alternator and battery tester for free. That's how I confirmed the alternators in my BB512i needed rebuilding a few years back...
     
  4. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    I would if I could,
    only thing is we do not have an Autozone in the UK, I have had the alternator tested on a bench and all is fine.

    It must be something electrical,

    Thanks for your input anyway

    Mark...
     
  5. jm3

    jm3 F1 Rookie

    Oct 3, 2002
    4,364
    United States
    Full Name:
    JM3
    I f I recall correctly, the GT4 has a heat shield on the back of the alternator that can inadvertently be installed (clocked ) incorrectly and touch a bare terminal.
     
  6. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    20,289
    Texas
    Full Name:
    Steve Magnusson
    And what about the rectifier (I can't recall if this is a separate part or if it is included inside the regulator assembly)? The warning light "looks" at the voltage difference between the "+" battery terminal and the (side) output of the rectifier, but is sure seems like your trouble has a thermal component involved -- i.e., if it works fine for you during the 1st half hour, it's going to also work fine during a quicky bench test.
     
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  8. tomoshea

    tomoshea Formula Junior

    Dec 29, 2003
    541
    Ireland
    Full Name:
    Tom O'Shea
    Had this problem before, in my case replaced the rectifier and cleaned a cruddy earth strap.

    It never actually caused the car to not start or stop while driving, I drove like that for about a year before pulling the alternator.

    Drive on.....
     
  9. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    Thanks all,
    Very helpfull.

    Mark...
     
  10. Champboat/Champcar

    Champboat/Champcar Formula Junior

    Jan 29, 2007
    875
    Freeport NY
    Full Name:
    Eric T
    I was having a problem with the battery or charging system on my Gt4 , I finally checked the negative cable going to the chassis in the front by the battery,I thought its to metal but heck its so far from the motor so I ran another ground from the battery to one of the starter bolts, doing this just made every electrical part on the car function better. Now I know that the chassis is connected from front to back and is steel so I cannot explain why it helped so much but it did .
     
  11. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    Thank You,

    I will check this out on my car.

    Mark...
     
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  13. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,268
    USA
    Full Name:
    Hugh G. Rection
    +1. Friend had a similar issue with his 348, every test of the Nippondenso alternator said it was fine...well sure, no one tested it for more than 5 minutes...He finally took it to the best shop in town, they ran it for 15 to 20 minutes and sure enough, the alternator voltage dropped....I forget what needed to be replaced, regulator or rectifier, but it was a 10 minute swap and $25, and he was good to go.
     
  14. anthonyh

    anthonyh Rookie

    Oct 13, 2008
    29
    Do a through check up of your battery. Make sure there is enough water in the battery. If you feel hot while you are on wheels then check your rediator too.
     

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