Keep Blowing 10A in Small Black Fuse Box

On my new to me 1982 KZ1000J, the 10A fuse in the small black fuse box keeps blowing. Three times it happened while I was sitting at a light and the bike just died and once as I was easing away from a stop barely rolling on the throttle. I borrowed other fuses from the main fuse box to get me going again, but they didn't last long either. It has never happened while on the throttle and the RPMs are up. I have gone through the wiring harness and checked for breaks or exposed wire grounding on the frame and found none. The battery is keeping a full 12v as well. I'm not sure where to continue. Any ideas?

Try this:The Dreaded Intermittent Electrical Problem!

Here is the most basic method I know:

1) Charge your battery if you can.
2) Disconnect the Black lead from the (-) Battery terminal... or Red form the (+) Battery terminal, it does not matter which one.
3) Connect one of the following test setups in series with the Battery terminal and lead:
3.1) A 12 V light bulb,
3.2) A 12 V test light,
3.3) A 12 V test buzzer or,
3.4) A 12 V horn... you get the idea.
4) With the Ignition Switch OFF, go through your harness and wiggle the wires while looking/listening for the test setup to go on/start buzzing.
5) With the Ignition Switch ON, repeat the test except this time the looking/listening for the test setup to go on/stop buzzing.
6) Be prepared to open the Ignition switch and check/test for solder joint failure and or circuit board micro breaks (don't ask how I know this ).
7) Be prepared to pull the wires out of the Head Light to test for failures at or near the grommet.
Be prepared to open the harness at or near the Steering Neck for failures. This is where wires tend to exhibit fatigue due to repetitive movement.
9) Be prepared to open the left and right switch gear to search for rust and or broken parts. CAUTION: watch out for fling springs, ball bearings and stuff. Do indoors on White sheet (again don't ask ).
10) Be prepared to follow the heavy gauge wire from the Starter Solenoid (Relay) to the starter for bare ware wire exposure. Especially near bends and grommets.
11) If you can reproduce the fault symptom your are pretty much home free. Be prepare to find and repair/replace any internal wire breaks, insulation break downs, exposed wires, rubber grommet failures, etc. Often, shrink tubing will solve the problem temporarily.

Not sure about your bike, but the small fuse box on my 81 650 is for accessories: one lead terminates somewhere near there, the other terminates at the headlite bucket.

Thanks for the responses, I'll try tracking the problem down this weekend. I was thinking because the fuse mainly blew when idling while stopped, it would point to a specific source. But I'll update if I find anything.

Just a guess on my part but mine did the same thing when pulling in the clutch or letting it out at a light. The wires were shorting out in the handlebars.

Well I just wanted to tie up this thread and let those interested know the outcome.

The fuse that kept blowing was the 10A in the accessory fuse box that led to the starter relay. The other end went straight to the main fuse box and nothing ever blew there, so I figured it had to be something tied to the other end and that began with the starter relay.

With the first test, I followed my factory manual and disconnected the starter motor and battery positive leads from the relay and connected my meter to the terminals. I turned the ignition on, pulled the clutch in and hit the starter switch. There was a single click from the relay and the meter stayed at zero. That's what I wanted, so so far so good.

Next I checked for voltage at the relay by connecting my meter to the two pin connector that the relay connects to and followed the same steps above. My meter read the battery voltage but the starter relay didn't click like it should have. Bang - problem found. I ordered a new starter relay from Z1 and installed it last week. Problem solved and no more blown fuses.

If you have a manual then this testing procedure is pretty easy to follow. If you don't have one, then I've basiclly outlined the steps above.

Peace

Congrats! Great troubleshooting.

Also, thanks for getting back to everyone... you'll never know how many members you've help out.

Best of success.
Bill

Dead shorts can be a nightmare sometimes even in the simplest electrical systems. Congrats on your sucess in finding yours. Gets you better in tune with the machine.

Congrats on finding and fixing the problem. This is one more example of why I say the factory manuals are worth their weight in gold. Just think how much money a dealer would have charged to find and fix the problem and how many manuals that would have bought. Ed

good thread...i just blew a fuse riding today....kinda dead give away when the whole curcus goes limp at once....teach me not to have extra fuses in the box...daytime so no big ...switcharoo...and broooom it was a go....rarely happens though...oh well....