How do I find a faulty ground?

Discussion in 'Electrical' started by sincityharley, May 31, 2011.

  1. sincityharley

    sincityharley Member

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    Im on a 2002 FLSTCI. Ive been having quite a few issues with performance loss as well as sputtering and also my fuel gauge appeared to have gone bad. After jumpering a wire from the the speedometer assembly acorn nut directly to the battery ground all of the issues disappeared. I assume this means that I have a bad ground somewhere. Now if someone can tell how I start looking for this ground or in what area I should start looking. It would be a great help.
     
  2. Hoople

    Hoople Account Removed

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    The factory wiring schematics inside the service manual shows exactly where the "ring terminal" grounding posts are. These are the central points where most all grounds are tied together.

    In my case for a 2009 Dyna, there are (2) stud terminals under the seat that tie in the battery, regulator, chassis frame ground, and wiring harness grounds altogether. This reduces the chances of having ground loops.

    The reason for the two studs and not having just 1 central point is sometimes grounds are segregated by design to reduce the chances of introducing electrical noise into sensitive ECM electronics.

    Start by looking at your factory schematics. As long as your bike is in it's natural original state, they will tell you everything you need to know.
     
  3. glider

    glider Veteran Member

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    Don't overlook a bad battery cable ground connection too or even a bad cable. They have been known to get corroded both at the connection and the cable inner strands themselves.

    Harley Davidson Community
     
  4. Jack Klarich

    Jack Klarich Expert Member

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    Hoople has given you the best advice here. To quick check to see if you have a grounded circuit, attach the alligator lead of a test light to the positive post of the battery, any thing you touch (METAL) with the probe end of the test light will light up the test light if you have a ground:s
     
  5. glider

    glider Veteran Member

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    Good advice by Jack....
    One thing I might add here and that is if you use this method, you can test for a ground that is present, however, it can give you a false indication in that all it takes is one strand of wire in the conductor to light the light and the circuit needs more than that to operate properly.
     
  6. BUBBIE

    BUBBIE Well-Known Member

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    On one of my old FXDS bikes, I had a similar problem and the grounds located like Hoople said Under seat.

    I needed to take off nut and the ground wire... Clean the painted frame where the grounding eye wasn't making GOOD contact with the frame.. Taking off the paint that was Not supposed to be there Did the Trick.

    signed....BUBBIE
     
  7. sincityharley

    sincityharley Member

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    So Ive located the ground failure. Apparently the fuel tank isn't being grounded. Is it supposed to be?? I am attaching a picture of the test lead that I ran from the tank bolt under the seat. I ran it to one of the ground bolts just a few inches away. Now everything works great. Ive taken the tank off a few times and I don't really recall anywhere that there was a wire from the tank to the frame or any other ground for that matter. Ive got both the Harley Service manual and the Harley Electronic Diagnostic Manual. One of them mentions a tank ground but does spell out specifically where it is (or at least I wasn't able to find it). I tested both the fuel pump ground at the tank and the fuel gauge ground under the tank. Both units do not work properly when this test lead from the tank to the ground is not in place. Both of them seem to be properly grounded as in I got continuity at the ground bolts. Although the thing that struck me as maybe odd is that I got continuity on two different ground wires. Both of those units when tested would light up the tester light on two different ground wires. So what am i missing?
     
  8. Hoople

    Hoople Account Removed

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    The tank is probably grounded through it's own mounting bolts but I would never expect that ground to carry return current for any electrical devices. Late model bikes are not wired like that. Maybe in 2002 things were different. Just look at the schematics and you will probably see a ground wire within the harness that is used for speedo, fuel gauge etc. You will probably find a fractured wire or bad pin when going through a connector.

    (Don't see the picture you uploaded)
     
  9. sincityharley

    sincityharley Member

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    Yeah forgot the picture. So your saying that I am still looking for a possible break in the harness somewhere??
     

    Attached Files:

  10. Jack Klarich

    Jack Klarich Expert Member

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    It is possible to have a ground( READ NOT A GOOD ONE) anywhere, in your pics I would try star washers they will bite in to the metal and not vibrate loose, check the wire ends also make sure they are clean and crimped tight