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Blowing fuse on start up

Hoople said:
I can only speak for my 2009 but the Battery fuse is a fuse that is Hot all the time regardless of key position. Why the Moco named it the "battery" fuse I don't know because I can think of better names. Not ALL but most other fuses are switched ON by key position. What the battery fuse feeds would only be a guess for me because I don't have an exact schematic for your bike either. The problem you face is this. Besides knowing what the battery fuse feeds,, you also need to know the start relay circuit wiring, the bars start button control circuit wiring, the TSM/TSSM control circuit wiring, and unless another member comes along with a schematic, how will anyone (you & us) actually know what wires feed what with any confidence... Wire colors also can change color from year to year which adds to the frustration. If schematics were not available, I would understand. You may not have any choice. A company is NOT required by law to make service manuals available to the general public. But HD prints and sells schematics to ease the frustration while working on their products..

Sure, you can get lucky and come across the problem without spending the money ($15.00/ PDF version ) for a service manual. It does happen.
Best of Luck.
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ok it's a fair point you've made and it's been taken on board :)

Do you have a link you would recommend for a schematic? Bearing in mind I'm in the UK?
 
haapened to a buddy of mine ,, it was a short in the rear signal light wire . tire had rubbed it bare due to a miss alignment of the tire and the addition of a sissy bar combo ... check your wires that are close to all moving parts
 
75shovelbobber said:
haapened to a buddy of mine ,, it was a short in the rear signal light wire . tire had rubbed it bare due to a miss alignment of the tire and the addition of a sissy bar combo ... check your wires that are close to all moving parts
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It blew the battery fuse? I'll check the rear light etc, thank you :)

I'm currently reading through ALL the stuff I have downloaded, (heavy going!) as was mentioned early in the thread, the fuse does seem to be linked to the speedo and the TSSM.
 
Hoople said:
(?)
I think I understand what your saying but how does having ground loops increase the current flow throgh the positive leg of the circuit where the fuse is placed.

Yes, I could understand what your saying was true if the fuse was in the Ground side of each circuit. Then leak currents could transfer to a different fused circuit and blow an unrelated fuse. That I could understand.
But in this case the fuse is in the positive leg of the circuit. May be wrong but I can't see leak current caused by ground loops blowing a fuse in the positive leg of the circuit.

Just applying ohms law to a simple DC circuit and saying if I increase the resistance, the current is reduced. So if the current is reduced, it is less likely for the fuse to blow as long as the fuse is in the positive leg of the circuit..
But who knows.....anything is possible.
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Ohms law works exactly as you state, for simple circuits, but the deal is when diodes and semi-conductors are in the circuit, transients can cause leakage currents that "sneak" backwards drawing more current from the source. In some applications multiple grounds can actually float ground return so negative voltages can be generated for less than a milli-second, but long enough to latchup digital circuits (especially CMOS ckts actually short, getting extremely hot) when equipment is powered up. Decoupling capacitors ("Y" caps, snubbing networks and back to back Schottkey diodes are sometimes used to prevent this if proper grounding cannot be achieved). The motorcycle has parts that "float" electrically like the swingarm, and steering/handlebar areas (and the rubber mounted engine) so special attention to the ground straps is important in these areas. :(
 
Yes, what you say is true. But in this case I would bet that if the OP carefully took the blown fuse apart, he would see that the fuse did not slowly melt from a slight or gentle overload. I would bet that the element of the fuse "exploded" giving proof that the cause was from kind of dead short taking place rather than leakage currents. More along the lines of what Glider suggested earlier.

I am sure you know where I am coming from since you work in this field. People just throw away and replace fuses when they blow without actually looking at the element. Important information can be extracted from just a blown fuse.
 
Hoople said:
Yes, what you say is true. But in this case I would bet that if the OP carefully took the blown fuse apart, he would see that the fuse did not slowly melt from a slight or gentle overload. I would bet that the element of the fuse "exploded" giving proof that the cause was from kind of dead short taking place rather than leakage currents. More along the lines of what Glider suggested earlier.

I am sure you know where I am coming from since you work in this field. People just throw away and replace fuses when they blow without actually looking at the element. Important information can be extracted from just a blown fuse.
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Well, I reckon you might have won your bet, as the fuses have been black, and burned out mostly 25% or more of their total length. An inexact science I suspect, but I take on board what you've said.

Tomorrow is a quiet day at work, I shall be hopefully running through the diagnostics on the speedo, see if I can learn anything there. As you have rightly said, the battery fuse appears to run only to the speedo assembly, the TSSM alarm thingamy, and the alarm siren also. I'll be having a look at them too, assmuing I dont get too many customers.

I work at a motorcycle shop, by the way. Have done best part of 20 years. Though not as a mechanic, I'm a salesman and manager. I could get one of my mechanics to fix this I suppose, but I want to do it myself. After all it's my bike. And the longer it goes on, the more stubborn I get about it :)
 
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