/5 blowing fuses.

Discussion in 'Airheads' started by Psiequalsone, Jun 19, 2019.

  1. Psiequalsone

    Psiequalsone n00b

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    Hello all,

    First time listener, long time caller...

    I picked up a non-running ‘72 R75/5 last spring and I’ve been working on it in fits and starts since then.

    I’ve got it running now but I’ve come upon an electrical gremlin:
    It will blow a fuse when the right turn signal is turned on AND the engine is running. It will not blow a fuse w the engine off.
    Engine ON left turn signal, horn, high beams, on: good. Right turn signal ON: blows fuse.

    Ignition on, Engine OFF right turn signal, left signal, high beams, horn, etc: good.

    Before I get elbow deep in electrical troubleshooting this, has anyone seen or heard of this before?

    Additional info: when I got the bike, it had the ignition switch board removed and everything wired to a toggle switch. I have since installed a Rocky Point ignition switch upgrade.

    Thanks.

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    #1
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  2. bpeckm

    bpeckm Grin! Supporter

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    Hmmm... clarify please: is it with ignition ON, or specifically engine RUNNING that does it....??

    ...AND: did it do it before you put in the new ignition switch? (A major hint in sleuthing is to go back to the last thing that was changed!)

    :D
    #2
  3. Psiequalsone

    Psiequalsone n00b

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    Engine running it blows the fuse w right turn signal. Anything else is fine.

    Engine NOT running (ignition switch on) right turn signal does NOT blow a fuse. Nor does anything else cause the fuse to blow.

    I don’t know if it happened before I installed the new ignition switch.
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  4. PaulBarton

    PaulBarton Been here awhile Supporter

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    I am assuming by "Engine Off" you mean the ignition is turned on but you haven't started the bike (or have just killed it). This would provide power to all Switched devices including turn signals. All systems check here, right?

    Now you start the bike and the RH turn indicator will blow a fuse ONLY when pressed, correct?

    What does the bike have for a starter relay? What about the flasher relay? In your headlight bucket I can see it doesn't have the OEM but can't tell what is there.

    The starter relay if OEM has a no-start function once running. Often these were replaced with generic ones from the FLAPS and this function would be lost. Based on your toggle switch I would look at the relay also. The generic relay will function fine (minus disabling the starter when running) but based on the install may have wires shorting somewhere. It's also a good idea to trace your own work and make sure there's not a "Doh!" hiding in there -- this is especially true if the turn signal was functioning properly before you installed the Rocky Point ignition.

    When I got my /5 years ago it had bar end turn signals (which I like and still have) but they would operate inconsistently. I kept tracing wires and trying to solve the problem without much luck. Over a winter I decided to clean up the wiring mess -- the main frame harness was gooey with electrical tape, the turn signal wires turned up similar inside the handlebars. After rewiring the bike I no longer had the issue. It appears the electrical tape splice was not effective.

    I share this to let you know I feel your pain. The electrical gremlins can be frustrating but armed with patience, an accurate wiring diagram and reasonable skill it can be solved pretty easily.
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  5. Big Bamboo

    Big Bamboo Aircooled & Sunbaked Supporter

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    You may have a chafed wire to one of the right hand turn signals, that only shorts when it's vibrating. Look where the wires leave the headlight bucket, where they enter the headlight brackets, and where it enters the turn signal. What amperage fuse are you using? I'm not seeing a turn signal relay?
    #5
  6. Psiequalsone

    Psiequalsone n00b

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    The starter relay is original. However, I did do the relay modification recommended by Snowbum.

    The flasher is a NAPA 552.

    Before AND after installation of the Rocky Point ignition upgrade the original flasher would flash for the LH signals but be constantly ON (no flash) for RH signal(ignition on, engine off).

    After replacing flasher w NAPA 552, RH and LH signal flashes w ignition switch on but engine off. And RH signal blows fuse when engine is running.
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  7. Psiequalsone

    Psiequalsone n00b

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    It’s an 8A fuse.

    I replaced the original w a NAPA 552. The original would flash for the LH side but constant ON for RH (ignition on, engine off).
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  8. PaulBarton

    PaulBarton Been here awhile Supporter

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    I’m with BigBamboo on this one. There must be chafed wire somewhere along the way to the rh turn signal. It sounds like the problem may have existed prior as that may be what affected the oem flasher. You could also swap wires (left to right) to see if right will work when wired to left. I don’t have the wiring diagram with me but it’s Blue/Red and Blue/Black from memory. That could help isolate the issue location. I’ve also jumped from one end to the other to isolate within a hidden section.
    #8
  9. Warin

    Warin Retired

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    Replace the fuse temporary with a head light globe ... this way the globe will go very bright when shorted, it will glow with indicator flashes.

    With the engine off I'd shake things to see what causes the fault .. if possible. If you cannot get it to happen with shaking .. then ?

    Try isolating the rear indicators and see if the fault is still there? Work on isolating where the fault is .. then eye ball it.
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  10. Warin

    Warin Retired

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    A constant on can indicate a blown globe ... check the globes? (from your initial conditions)

    Arr that makes no sense .. as it works when the motor is off. Back to where I was ... headlight globe for the fuse and wiggle things.

    Unless the globe itself is shorting...
    #10
  11. bpeckm

    bpeckm Grin! Supporter

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    Some good ideas above... You could also try this: remove the bulbs from the right (shorting) side and see if it still blows with engine running. This would/might isolate the problem to the chafe/wires themselves. If it IS the wires, I would start with that funky path of the front one through the headlight mount.

    Frustrating yet fascinating.
    #11
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  12. Psiequalsone

    Psiequalsone n00b

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    Well, thanks everyone for the advice.

    Looks like the problem is in the turn signal/starter switch.

    When I started troubleshooting this evening, the fuse started blowing weather the engine was running or not. Made it much easier to isolate.
    #12
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