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Thread: Voltage anomaly

  1. #1

    Voltage anomaly

    Hi guys.
    Got a real strange one here. First some background
    2006 XB9SX
    Around 70 000 km.
    Used as my daily commuter approx 85km per day
    Replaced VR ,stator and battery 2 years ago.
    Shes been perfect electrically, but I parked her the whole
    of last week due to a leaking aftermarket exhaust issue, which
    I repaired on Saturday.
    Gave her a wash and put her in the garage.
    This morning took her out the garage for a run with the wife.
    When I switched on the ignition there was nothing, dead.
    Popped off the seat, connected jumper cables, still nothing.
    Left her and took the GS.

    This afternoon I checked, and the battery tests perfect.
    After a lot of troubleshooting and checking the wiring diagram, I found
    that on the key switch, I only have 3,5V instead of 12. I ran a temp jumper to
    the switch, and she came to life, even started.
    I then disconnected all the plugs under the front cover and while
    disconnected, I get my 12V, plugging everything back in, I find that as
    soon as I connect the dash, it pulls the Voltage down.
    There are no earth (grounds) in the front as it seems other Buells have.
    That was my first thought.

    Thats about where my expertise ends. The dash must be ok as it works
    when I use a jumper.
    I'm open to all reasonable suggestions guys.
    Thanks

  2. #2
    Senior Member Cooter's Avatar
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    Thanks for the info and breakdown of what you have done already. It really helps!

    A bad ground wouldn't cause your meter to drop when plugging in the dash, the meter has it's own ground. That means theres an issue on the (+) side.

    Try leaving the dash plugged in and just wiggling that connector and wires?

    You didn't mention checking fuses and relays, both are in that key switch circuit. FYI, the relays are interchangeable.

    Post up what you find!

  3. #3
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    You probably know this already but the first thing I check when I have any kind of electrical problem are the grounds, I make sure they're clean and then I lube them with roller chain spray, it has an anti-corrosive in it, this lasts a long, long time in preventing corrosion. Check and clean all of your fuses, and if they're old replace them, also change around the contacts and see if there is any change. Other than that it might be the wires going into the key or the key cylinder itself.

    P.S. I'm not that good with electric either other than what is listed above.

    Good luck.

    Or better yet, listen to what Cooter is telling you, we posted answers at the same time.
    Last edited by njloco; 01-26-2020 at 07:31 PM.

  4. #4
    Thanks all.
    I am fortunate to have my wife's '05 model to swap parts with as necessary.
    I did check each fuse by removing it and using a multi-meter. The relays I did
    swap around with no change. The only grounds I found were the battery ground
    to the side rail, and on the opposite side rail, two black wires grounded, which a removed and cleaned.
    I'm going to start disconnecting sensors to see if one of them has maybe gone.
    I did the wriggling of wires quite extensively with no change. What I did see on one occasion was
    the needles sweep when I disconnected the key switch connector, even though it
    was switched off at the time. This happened only once though, so have not been able to
    replicate the cause. Its definitely something pulling down the 12V , but not affecting
    the battery which remains at 12,7 V.
    I'll play around again tonight.

  5. #5
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    Many XB's have a ground behind headlight and slightly lower on the frame.

  6. #6
    Quote Originally Posted by njloco View Post
    Many XB's have a ground behind headlight and slightly lower on the frame.
    Mine has a torx bolt in the headstock, but nothing is connected

  7. #7
    Nailed the bugger.
    Since the issue was low voltage at the key switch, I traced the wiring back to the fusebox, where I measured
    13 Ohms between the 2 points. That would certainly give me the voltage drop I saw.
    I suspected a bad joint, and wriggling the wires behind the front panel revealed nothing.
    Then I moved further back in the loom, and when pushing it hard against the frame just ahead
    of where is exits the plastic guide inside the frame, I saw the conditions change.
    That pointed to an issue in the loom bundle.
    I stripped the front binacle off and freed up the loom up to where it entered the inside of the
    frame (pic1), and removed the cloth tape. Then I moved further back and removed the fibreglass
    tape, and saw the issue (pic2). The red wire was chaffed, but not right through the insulation.
    It did however look suspect, and when I bent it, I noticed it was broken inside. I pulled either
    side of the chafe, and it came apart (pic3). Although it hadnt worn through, teh insulation had been
    compromised enough to allow water in , which corroded the copper, which was evident from the green
    verdigris. Fortunately that particular wire splits into two and was a bit longer than the others. This allowed
    me to cut out the corroded bit, solder it together, add two layers of heat shrink and some insulation tape.
    Wrapped the loom up, plugged everything in, and she fired up fist time.....success.
    Tomorrow I will re-assemble and be thankful for the "easy" find.

    Pic1.jpg
    Pic2.jpgpic3.jpg

  8. #8
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Beebop View Post
    Nailed the bugger.
    Since the issue was low voltage at the key switch, I traced the wiring back to the fusebox, where I measured
    13 Ohms between the 2 points. That would certainly give me the voltage drop I saw.
    I suspected a bad joint, and wriggling the wires behind the front panel revealed nothing.
    Then I moved further back in the loom, and when pushing it hard against the frame just ahead
    of where is exits the plastic guide inside the frame, I saw the conditions change.
    That pointed to an issue in the loom bundle.
    I stripped the front binacle off and freed up the loom up to where it entered the inside of the
    frame (pic1), and removed the cloth tape. Then I moved further back and removed the fibreglass
    tape, and saw the issue (pic2). The red wire was chaffed, but not right through the insulation.
    It did however look suspect, and when I bent it, I noticed it was broken inside. I pulled either
    side of the chafe, and it came apart (pic3). Although it hadnt worn through, teh insulation had been
    compromised enough to allow water in , which corroded the copper, which was evident from the green
    verdigris. Fortunately that particular wire splits into two and was a bit longer than the others. This allowed
    me to cut out the corroded bit, solder it together, add two layers of heat shrink and some insulation tape.
    Wrapped the loom up, plugged everything in, and she fired up fist time.....success.
    Tomorrow I will re-assemble and be thankful for the "easy" find.

    Pic1.jpg
    Pic2.jpgpic3.jpg
    Wait... what? Logical troubleshooting?!?!?! Who are you?

    Nicely done

  9. #9
    Senior Member BuellyBagger's Avatar
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    Quote Originally Posted by 34nineteen View Post
    Wait... what? Logical troubleshooting?!?!?! Who are you?

    Nicely done
    Yeah no kidding, doesn't seem to happen around here much. Good find!

  10. #10
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    Sir: it's the dreaded "red wire failure" scenario. it's the main feed wire to the front of all XB models. i mentioned it last october in a thread titled "CEL intermittent". anytime you have a complete intermittent power failure that is sourced to a suspected faulty ignition switch assembly.....and you've replaced the key switch relay...and eliminated the ignition switch as the culprit....it is always the red positive power feed wire that's the culprit.



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