Wednesday, July 13, 2011

main fuse blows on yamaha motorcycle

If the fuse blows when the ignition switch is turned on, that means 1 of the 5 loads fed from the switch is shorted to ground.

The 5 loads are regulator, tailight, ignition coil, headlight, and misc such as turn signals, horn, brake switches. You have fuses for the ignition, headlight and miscellaneous. Remove all 3 of those fuses and unplug the regulator. Keep the main fuse fitted.Then turn on the ignition.If the fuse blows, then the fault is in the tailight. If fuse does not blow then plug in the regulator, and see if that blows the fuse.If the fuse blows then problem is regulator.But if fuse does not blow then Just keep testing by process of elimination. The kill switch allows you to eliminate the coil/coils as the faulty load.
There are 2 major spots to look at. 1 is by the seat under the plastics where the loom is attatched to the frame. The other sounds like your problem by the handle bares where all the wiring comes up and to the bars. Easiest way to find it is to take the plastics off and start looking. You can also get a circuit breaker to replace the fuse while you hunt for it that way you wont have to replace it over and over and over.

i found the first short underneath the seat where it connects to the frame. thanks i'll look for the next one on the steering column
In my case the speedo wire was shorting.----------
In my friends case the rectifier was faulty and has to be replaced.-------
.found a short along the steering stem. Patched 'er up and it worked perfectly.

Yeah i just found it, it was once all the wires come out of the steering stem right there in that area the wire was rubbed off and shorting out.

check for a loose or bare wire shorting out to ground...disconnect the negative terminal wiring from your battery and connect a voltmeter from the wiring to the terminal...with the ignition off take voltage reading...if you read battery voltage you have a short in the system