Author Topic: ARgghhh Electrical problem!  (Read 513 times)

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Offline cwchan

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ARgghhh Electrical problem!
« on: July 13, 2011, 01:09:07 PM »
HELP!

Tail light fuse keeps blowing as soon as in turn the key to the "RUN" position.  The following lights turn on when the key is in the "RUN" position,

the tail light is 8 watts
the stop light is 23 watts
the tacho and speedo have a combined total of 3.4W*4= 13.6 watts
the neutral & oil light have 3.4W*2 = 6.8 watts
headlight low beam is 40W (?)

a) for a max total of 68.4 watts if the TAIL light is on.
b) for a max total of 83.4 watts if the STOP light is on.
c) for a max total of 91.4 watts if both the TAIL and STOP light are on.

This translates to amps = Watts/12volts

a) 5.7 amps
b) 6.95 amps
c) 7.62 amps

This means that even if all these lights were run through the tail fuse (which they are not) the fuse should have hardly enough amperage to blow the fuse.  I even tested out a 10Amp fuse and it still blew.... i know that electrical can actually be much more complicated than this though....

Here's how it all started.  I removed the front stock signals.  Everything still worked as it should.  My new aftermarket turn signals and tail/stop light came in.  i installed all of them.  The issue was that the tail light only has 2 wires coming out instead of 3.  I read that the body of the light serves as a ground.  Because the 2 wires were not the same color as the harness so i had to test to see which was which when installing it and kept swapping the tail light wire & stop light wires before determining the correct wiring connections.  At first i only had an intermittent problem in that the tail light was on & off periodically.  Then it stopped lighting up.  Checked and the fuse was blown.  I thought it could be due to the new tail light and reinstalled the old one.  Fuse is still blowing...

I thought about riding the bike without the tail light but i know its dangerous and not legal..

I'm hoping that someone more experienced will be able to help out here to hopefully narrow down where the problem might be coming from.