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Thread: Blowing 30A fuse - When Hot or Not?

  1. #1

    Blowing 30A fuse - When Hot or Not?

    Hoping someone else has seen this.

    My '08 Uly has been blowing the main fuse lately. It happened about a year ago on my way home from work (7 miles). I had no spare, so I put a 15A in the socket, and got home safely.

    Then a buddy and I went for a ride about a month ago. He took a wrong turn, and we ended up on a dirt road for about 7 miles. A lot of powdery stretches. The bike ran great, but twice, when I was grunting through powder sections, the fuse blew. After getting back on pavement, the bike ran great for the next 80 miles.

    Yesterday, when I was going to an appointment, I was in stop-and-go traffic. Leaving a light, I entered the median for a left turn at a good speed, then applied a firm brake and made the turn into a bank parking lot. The bike died as I went down the 'ramp'. Again, blown fuse.

    I suspected it might be a heat/fan issue, but the fan seems to run normally (on/off at 15 mph); and yesterday shouldn't have been that hot. I thought it might be when the fan goes to 'High', but apparently the '08's and up are single speed. BTW, the fan was replaced a year ago - after the first fuse failure.

    The failure doesn't seem to be related to motion of the bike or the steering.

    I've set the bike up in the garage with a charger and turned the ignition on and 'wiggle tested' every wire and harness I could. No effect. I pulled the fuse block and gave it a close inspection. No apparent issues. Visual inspection of all wiring doesn't reveal any chafing or frays.

    When I've checked for codes, there hasn't been one - I assume because the fault kills the ECM too quick to set a code.

    So, anyone have any idea what to look for? I'm riding the bike regularly regardless. I just carry a contact lens case full of 30A fuses. I need to look for a circuit breaker...

  2. #2
    Senior Member 34nineteen's Avatar
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    Are the fuses blowing or melting? Its a big difference as to what is really happening with the circuit.

  3. #3
    3419 - they are going instantaneously. No burn marks. No hint what is happening, other than (of course) I'm getting a huge demand, or a direct short.

  4. #4
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Pushr0d View Post
    3419 - they are going instantaneously. No burn marks. No hint what is happening, other than (of course) I'm getting a huge demand, or a direct short.
    Then it is a short to ground. You have something grounding out somewhere.
    If the fuse was melting, thats a sign of increased load or high resistance in the system.


    Quote Originally Posted by Pushr0d
    The bike ran great, but twice, when I was grunting through powder sections, the fuse blew
    Quote Originally Posted by Pushr0d
    Yesterday, when I was going to an appointment, I was in stop-and-go traffic. Leaving a light, I entered the median for a left turn at a good speed, then applied a firm brake and made the turn into a bank parking lot. The bike died as I went down the 'ramp'. Again, blown fuse.
    Quote Originally Posted by Pushr0d
    The failure doesn't seem to be related to motion of the bike or the steering.
    Um, yes it does.

    Quote Originally Posted by Pushr0d
    I've set the bike up in the garage with a charger and turned the ignition on and 'wiggle tested' every wire and harness I could.
    You need to check them all. Not just the ones that you can get to.


    Quote Originally Posted by Pushr0d
    I pulled the fuse block and gave it a close inspection. No apparent issues. Visual inspection of all wiring doesn't reveal any chafing or frays.
    Correct! If it was an apparent issue, you would have likely said "The apparent issue is the harness rubbing on the frame" or something like that. If visual inspection revealed chafing or frays, I'd imagine you'd take action, and this would be a non issue.


    Quote Originally Posted by Pushr0d
    So, anyone have any idea what to look for?
    What you need to look for is a wiring diagram and trace the wires coming from that fuse. buellmods.com


    Quote Originally Posted by Pushr0d
    I need to look for a circuit breaker...
    This will only mask the problem somewhat. When the wire shorts out again, the circuit breaker will pop, stalling the bike, until the breaker cools and resets. The short is only going to get worse.

    Chasing a shorting wire can be a daunting process, but you are off to the right start. You may have to start pulling the bike apart to access all of the harness. It sucks but its no different than replacing $5 worth of intake seals or a $10 rocker box gasket.

  5. #5
    Senior Member Barrett's Avatar
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    Aaron correct about this often times being a daunting task to track down a substantial short-to-ground....substantial in that it has the power to pop a 30A fuse. When I've dealt with this I've always started up in the headlight bucket area where big current draw items reside...and the dreaded "chafed red wire" scenario inside main harness that wraps around the steering head. In most cases that's where the problem lurks and the "wiggle test" seldom reveals it. Bumps...tight sharp turns....wheelies gone bad force the issue and pop the fuse.

  6. #6
    Senior Member 34nineteen's Avatar
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    Here is a copy of a 2007 XB wiring diagram showing your potential areas for starters. Rather than just wiggling random wires and hoping for the best.

    2.jpg

  7. #7
    Senior Member 34nineteen's Avatar
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    Quote Originally Posted by Barrett View Post
    the dreaded "chafed red wire" scenario inside main harness that wraps around the steering head.
    Well, the diagram is showing it is a red wire on that circuit directly connected to the 30a fuse.

  8. #8
    Senior Member 34nineteen's Avatar
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    and heres where that diagram left off. This is for a regular lightning and not a ulysses.

    4.jpg

  9. #9
    Thanks gents! Now the weather has cooled, my garage is no longer a sauna, and I can get serious into a good look-see.

  10. #10
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    Will be interesting to see where this short is?



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