Finding bad grounds...

Discussion in 'Electrical Systems' started by branbell, Dec 10, 2017.

  1. McCune

    McCune Veteran Member

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    Aug 22, 2015
    st.george utah
    I played with the new on from Snap-on but could get past the high price. I use my Fluke meter to test for a draw and have many years experience with it. The thermal imaging would be nice for some that are not as comfortable using a meter, but you said it don't work so there goes that idea.
     
  2. branbell

    branbell Veteran Member

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    Jun 6, 2011
    Myrtle Beach, SC
    I think I've got it down to a bad alternator.

    It was funny..I had the battery out of the car to charge and put it back in this morning. Checked it with the clamp meter and it read between .03 and .05 which was great considering it was .5 and higher.

    So I started the car and ran it for about 30 minutes in my driveway..pull it back in the garage, turned it off and checked it again. Now it's reading .5 and higher but then I heard a small whining noise and moved my ear closer to the alternator and the noise was coming from there. I unhooked the alternator and the readings dropped back down to .02 to .04.

    I believe I need a new alternator.
     
  3. SRGN

    SRGN Veteran Member

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    Feb 20, 2009
    Central NJ
    I was leaning towards alternator or regulator from the beginning, but I never condemn any part until diagnostic work has been done. Next you need to make sure you have no voltage at the excitation terminal with the car off. You may also have a regulator stuck on if your car has an external voltage regulator.
     
  4. McCune

    McCune Veteran Member

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    Aug 22, 2015
    st.george utah
    Usually if the alternator is the culprit it will draw from 2 to 4 amps because the alternator rotor is energized from a leaky or shorted diode. Not saying that isn't your issue just not the normal draw numbers.
     
  5. branbell

    branbell Veteran Member

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    Jun 6, 2011
    Myrtle Beach, SC
    Anyone have any experience finding/fixing the issue with one?

    This is what I have...came with my Billet Specialties serpentine kit: https://www.summitracing.com/parts/pwm-67802/overview/

    I'd rather fix it than spend another 200+ on one.
     
  6. SRGN

    SRGN Veteran Member

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    Feb 20, 2009
    Central NJ
    Looks like a cs130 to me. Get it rebuilt locally.
     
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  7. branbell

    branbell Veteran Member

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    Jun 6, 2011
    Myrtle Beach, SC
    Found a local guy that is suppose to be pretty good and reliable...gonna go by today and see what he says.
     
  8. Itsadryheat79

    Itsadryheat79 Veteran Member Lifetime Gold Member

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    Aug 4, 2009
    Chandler, Arizona
    Another option would be to put a quick disconnect on the battery cable. Then you can disconnect the battery while it’s sitting. Simply reconnect it when you need it. The ones with the green knob are inexpensive and easy to get and install on the battery.
     
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  9. Lynd McCormick

    Lynd McCormick Member

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    Oct 6, 2017
    Finleyville, PA
    Don’t be afraid to split that alternator wide open, there’s not much to them or a starter as long as you have a basic electrical knowledge of what to test. Many of those parts are readily available.
     
  10. Jim Streib

    Jim Streib https://www.flickr.com/photos/121766713@N04/albums

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    Apr 6, 2004
    Saint Louis, MO USA
    The link you posted https://www.summitracing.com/parts/pwm-67802/overview/
    might be a 1 wire style alternator or one that can be converted to be able to use the original GEN light in the car and while I do not know the differences between the regulators inside, or how yours is actually wired, make sure you get the right one.
    While on the GM alternators with the built in voltage regulators require the alternator case to be split apart, I do know I had to replace a set of brushes on my daily driver (Ford) and on their design you removed 4 torx screws and the brush and regulator assemble came right out of the back case. Boy was that a simple swap.
    On the GM ones you can use a paper clip to hold the brushes back while the cases are being bolted back together and then the clip is slid out.
    This is the alternator on my 68 and while this year had the external regulator, it comes apart easily just like yours. I had to take mine apart to clean off the Arkansas Chrome someone had painted it and then also to lube the bearings back up.

    https://www.flickr.com/photos/121766713@N04/albums/72157650744749350

    Jim
     

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