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Blowing Fuses!

Discussion in 'Technical and Troubleshooting Torque' started by Browncoat, Jan 4, 2011.

  1. My YZF1000R periodically blows the 15A signal fuse which covers indicators, brake lights, dash lights and tacho. If I replace the fuse sometimes it blows again straight away and sometimes it will last a couple of weeks before blowing again..

    How should I proceed in diagnosing the problem? I guess i'm looking for a short circuit? Why would it be so intermittent?
  2. Fuses are variable in their performance, when the ambient temperature is high the fuse will blow earlier, the 15A figure is the maximum current it will carry on a continuous basis usually at 25 C. If the figure exceeds 15A marginally e.g. 16A the fuse will carry the current for a while typically around 10 - 15 seconds. If the current is higher the time it will carry the current is less so shorts will blow a fuse almost immediately.

    So after that brief blurb on fuse ratings :) Some questions first:

    Are all the light bulbs the manufacturers power rating. i.e. you haven't replaced any of them with after market higher rated ones?
    Does it happen more often in hot weather?
    If you have a multimeter, What voltage do you measure across the battery with the bike revving to cruise level RPMs?
  3. Thanks for the info on fuses. Yes it does seem to be that the fuse is blowing when the ambient temp is higher.

    I havent personally replaced any bulbs but i'll have to check those now.

    I do have a multimeter, so I can check the voltage across the battery as you say.

    I'll post back when I have the results.
  4. To save blowing fuses you can put a light globe in place of the fuse and if a dead short appears it will glow very brightly.

    What are you doing when it "blows"??

    Check that the brake globe is the correct type, I've often seen cars that have had single filiment globes fitted instead of dual filiment (Brake/tail) globes. This shorts both the brake and tail/parker circuits together and also mean if the headlights are turned on the brake lights come on all the time, also means more lights are connected to the fuse than it's designed to have connected to it........
  5. I'm not doing anything out of the ordinary when it blows. Just riding.

    The brake/tail light is definitely a dual filament type.
  6. Fair enough but are you braking while the indicator is flashing??

    What on the circuit is in use when lets go.

    You need the skills of Sherlock Holmes at times to find these sort of not so obvious faults and the more "facts" or "clues" you have the easier it is.
  7. Thats the 20 million dollar question isn't it :)

    Its like watching a kettle boil.. (" a watched kettle never boils"). Every time I concentrate on watching to find what blows the fuse it doesn't blow. It would probably be much easier if it just kept on blowing straight away.

    I've tried to replicate the fuse blow with using both brakes and indicators all the same time but haven't narrowed it down yet.

    I'm just hoping it isnt something in the dash lights/tacho area cause i'd imagine that would be a real pain in the ass.
  8. I found a wiring diagram for a YZF1000R but it is European release version so may be slightly different. In this drawing signal fuse also does horn and a separate services socket intended for alarm systems. Do you have a alarm system on the bike?
  9. Intermittent fuse blowing in a circuit that connects the handlebars to the rest of the bike? I'd be looking for chafed or pinched wires around the headstock, where the loom gets bent every time you turn the bars.
  10. No alarm system. Forgot about the horn.. don't think i've ever used it anyway :)

    The wiring loom around the headstock makes sense. I'll have to look into that as well.

    If only I didn't have to work..

    I'll get to it soon. Let you know what I find.

    Thanks guys.
  11. Pat beat me to it.

    A sudden fault will usually be found where the wiring can move or be hit and damaged.
  12. Can you put an ammeter across the circuit to see the current draw ? Maybe trial and error to see which globe is causing the spike which blows the fuse. Some cheap fuses are crappy too: it pays to spend a few dollars more on good quality fuses,not some shitty fuses from China.
  13. NEVER put an ammeter across a circuit!
  14. Ahhh, well you know what I meant. It is the Ac/Dc thing. I have never had any complaints when I use my probe.
  15. No Nitekreeper, is right it is a bit more catastrophic than just leaving it on AC or DC. When measuring current a multimeter is close enough to a short so putting it across a voltage will destroy the current circuit in the ammeter. I know what you meant but I have seen lots of ammeters screwed that way. You need to be in series with the circuit and choose a high range on the meter.

    But you are right it will give you the steady state current. It may not necessarily show an intermittent short as other posters have put forward as the possible fault.
  16. Solved!

    My brake/tail light assembly has twin bulbs(both brake/tail globes) One of the bulbs was broken(the glass was shattered) and the little copper wires that normally hold each end of the filament were flapping about. I surmise that under certain conditions eg. bumps in the road, hard acceleration or braking the wires were touching each other and shorting.

    I replaced the broken bulb and havent had a fuse blow since.

    Dont know why the glass bulb would have been broken though.

    Thanks for all the assists and advice.
  17. Glad it is solved, always good when you hear back the problem is resolved.
  18. and the consultancy invoices are heading your way via snail mail :D