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Im blowing out the main fuse on my bike rather frequently. im quite sure that its due to the new tail light I put in. None of the other fuses get blown (headlight, ignition or lighting). on the xs400, you can remove all fuses except the main, and the rear taillight still glows. Often enough, the taillight bulb may fuse and then the fuse stays intact.

my question is that I swapped the two bulb OEM taillight with a single bulb (better looking) taillight. part of me cafe racer mod. since then I've been having this trouble. the other connections are duplicated. I also used the OEM connectors up until the taillight assembly...

So is too much current being sent through the system. i believe that the wattage of the bulbs is the same... there was no info on the OEM bulbs. the electrical connections all have rubber sleeves so no metal to ground contact is taking place. Should'nt two bulbs in parallel sink more current than a single bulb??

Confused!!!!

Is the fuse the right amps? Are you sure that the bulb is burning on the lesser bright light for the running light? Is the ground well grounded? Are all the wires taped? I don't know what else It could be. I hope this will help you out.

Yes to all those questions. Im quite sure it is the taillight that is the source of all these problems. Im hoping that if all else fails an electronic isolation circuit using a transistor switch will help. At this point, Im seriously all out of ideas .

I added a head light to my vulcan, I used a relay switch from a car. One that would run the fuel pump or maybe the electric cooling fan. And ran a circuit from the bat throught the relay, for the light. You may try this for your light.

Sounds like your new light is drawing more power than your old set-up, for some reason. Doesn't sound like a short in the wireing as you checked that. Double check your ground, just for kicks. Your new light isn't a halongen by any chance?

Installing a relay is not a bad plan, or you could try one of those LED bulbs that have an 1157-stlye base on them. The just swap out with the stock bulb and should draw less juice.

wait... when you say double check the ground it only means to check continuity and sufficiently low resistance with say the engine ground and battery -ve right??? I mean I've gone over that a number of times and apparently it seems OK. So I'll look at a lower wattage bulb or possibly a series resistor.

thx

ninterider: So your relay is permanently in the 'on/magnetized' state whenever the headlight is on?? Still, it makes sense though, the relay windings are definintely more resistance than the bulb coil...

oki thx.

I have the coil connected to the high beam side of the head light. When I switch on the high beam the light comes on with the original light. When going back to dim the light goes off. The light has it's own fuse and it runs directly off the battery. It is a small relay about 1" x 1". Yours will only come on when working the brake lever or paddel.

OK so I thought it was the bulb and surely I was using the high wattage bulb that came with the custom taillight (if you can call autozone taillights custom). I now have a bulb that is a little below the OEM wattage.

That however worked for all of 3 days.... and now my bike chewed up another fuse this is

I've held my tongue on this because you have convinced yourself that the problem lies with your light bulb, but it's becoming obvious that you most likely have a wiring issue. You need to go through the whole thing again with a fine tooth comb and with some patience to find out the problem.

You have an old bike. It's very likely that you installed the rear tal light properly, and something else on the main fuses circuit is causing your problem. just trace the circuit on the wiring diagram and do the same on the bike step by step bit by bit.

Having the main fuse blow constantly is a real problem and it's going to take alot of patience to resolve the problem. Good luck