How to trace a short

Discussion in 'Electrical Systems' started by Aceshigh, Jun 13, 2007.

  1. 78LT383

    78LT383 Veteran Member Lifetime Gold Member

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    Great writeup, Aces!

    Two other things to consider when I've chased similar demons:

    1) Don't forget those things you've added that connect to the battery all the time but may not go through your fuse panel, like radio memory wires, amplifiers, and MSD boxes. I've found excessive drains from each of these things in some cases. The MSD one had me stumped for quite a while one time.

    2) Don't use heater hose, fuel hose, etc. as an electrical insulator. These have a lot of lampblack in them, which is rich in carbon and is not a very good insulator. I thought I was really clever using it to insulate a battery cable one time but later discovered that with a meter I could actually measure some continuity from one point in a hose to another! Hose is great as a protecting cover over wire against abrasion, but the insulation must be intact under the hose.
     
  2. earlysecond

    earlysecond Veteran Member

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    Thanks for making this a stickie. . .it was easy to find and saved me from asking AGAIN. . .that is the whole point of a stickie is it not??- haha
     
  3. earlysecond

    earlysecond Veteran Member

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    My thanks was premature.

    If you set the meter to measure volts and there is no draw, should it read 0 volts?

    Secondly, I was never able to set the meter to show anything but 0.00 when set to measure milliamps DC the three dots . . . with a _____ under it.

    What am I doing wrong, the battery went complelty flat!

    Thanks in Advance,
     
  4. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    Yes they do...in fact in a pinch I have actually used a piece of fuel line as a plug wire.:eek:
    1 hellofa light show in the dark:eek: .....but i made it home.:cool:
     
  5. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    If you have zero draw from a fully charged battery, and the battery dies, there is an internal short inside the battery.

    That is, IF:

    You connected the device correctly and it is functioning correctly.
     
  6. clay's70

    clay's70 Moderator Staff Member Lifetime Gold Member

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    I have a short I am trying to find. I am getting continunity between the
    Batt. stud on the alt. and the alt. case which of course
    bolts to the block and goes to ground!

    Should this be happening??
     
  7. 78LT383

    78LT383 Veteran Member Lifetime Gold Member

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    No, it shouldn't. The diodes are probably shorted, it used to happen a lot more than it does on modern cars.

    The easiest way to confirm is to pull it off and have it tested at your local parts store. You can take your meter to compare the measurements you made to the same measurements on a rebuilt one.
     
  8. FlaJunkie

    FlaJunkie Veteran Member Lifetime Gold Member

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    I just re-read this post and saw this...LMAO! :D
     
  9. clay's70

    clay's70 Moderator Staff Member Lifetime Gold Member

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    Replaced the diode and the reg. in the alt.
    and all is good. I also went to the junk yard
    and picked up a spare alt.
     
  10. 78LT383

    78LT383 Veteran Member Lifetime Gold Member

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    Good deal!
     

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