Topic: Same blown fuse

[jsnss14]

My '81 650c blew the fuse for the taillight, gauge lights, and front running lights. Since I'm the original owner and never blew a fuse before I thought I'd try another. I turned the ignition switch on and watched the fuse light up and blow. Anyone have this happen and can tell me where to start diagnosing? I do have the Clymer manual which shows the electrical diagram, but I just hate dealing with electrical problems. Electricity is not my friend!! Thanks, Jim

[Serge]

I just dealt with the same thing on my '78 750f. I do not have any experience with bike's electrics and  I could not read through the bad copy of wiring diagram I had so I got couple boxes of fuses and did the following:

1. put a new fuse is in
2. disconnect one of the lights which does not work when fuse is blown
3. turn on ignition and watch the fuse - if it is still get blown, go to step 1 and pick up another light

I found the fault in the spedo backlight. I guess it could be in the wiring harness itself or in the ignition switch and you will still get a blown fuse with all lights disconnected ...

I guess you can save the fuses if you first disconnect all the things, but then you gotta remember how connect them all back 

good luck - serge

[jsnss14]

I ended up taking out all of the bulbs first and when I got to the last one, guess what? It was one of the speedo gauge bulbs. Thanks for the help Serge.

[Serge]

Jim, I am glad it worked out for you !   Actually, I did not touch the  bulbs, I disconnected the wires from the main harness - this seemed faster and eliminates any shortage in the sockets and on the way...  I still need to check out what is wrong with my spedo backlights - I just left it disconnected as soon as I got my taillight back on and became legal to ride after dark again. 

[oldbiker]

When this happens, a good tip is to put a 12v bulb in the fuse position. This will light up because of the short circuit but will protect the wiring while you search for the fault. when you find the fault this bulb will GO OUT. This saves you blowwing lots of fuses while you search.

[Bob Wessner]

Nice trick/tip, gotta remember this one.