Maybe it is not so confusing .

It sounds like you have a short to ground somewhere in the on the output side of the left brake switch. The output side of the brake switch goes to the brake light as well as the starter motor activation circuity. It could be anywhere in those wires (or parts).

Here is a couple common ways that the starter interlock is wired up on quads. Again, I don't have a wiring diagram specific to your KFX 50 so I'm left with trying to use common wiring schemes and trying to figure out which is most like yours:





Note that in both schemes the starter is engaged by applying 12 volts across the starter solenoid actuating coil. In scheme "A" 12 volt power get to one side of the starter solenoid vis the fuse, ignition switch, and brake switch in that order. The other side of the starter solenoid coil gets grounded when the start button pushed. In scheme B on side of the starter solenoid coil is grounded all the time. 12 volts is applied to the other side through the fuse, ignition switch, brake switch and starter button.

On starter solenoid, what are the wire colors of the two small wires that come in via a connector? Be sure to report only the wire colors in the main wiring harness - not the colors of any pigtail wires hanging off the solenoid itself.

In a similar fashion what are the wires colors on your brake light?

What are the wire colors on your ignition switch?

What are the wire colors on your brake switch?

What are the wire colors on your start button?

Again be sure to report only the wire colors on the main harness side of any connectors that feed pigtail wires going to the actual part itself. The idea is that we can use these wire colors to trace out the harness without taking it apart - i.e. if a yellow with black stripe wire enters the harness it will still be yellow with a black stripe wherever it comes back out. By looking at what each end of the yellow/black wire connects to we can start to put together the actual wiring diagram.

Once we figure out what scheme above is being used (or if your quad is using yet another scheme) we can start measuring with a meter.

But you might also want to look carefully at the connections at the brake switch, the starter solenoid, the brake light itself, and the start button. You might just get lucky and see something wrong.

You can also try unplugging the start button, the solenoid input wires (the small ones), the brake light. Then turn on the ignition switch, apply the brakes and see if your fuse still blows. If it doesn't blow plug the three things back in one at a time until the fuse blows. That will give further clues as where the problem resides...

 

So where exactly did your wire these fog light into your ATV wiring? I'm just wondering if there is a connection to your fuse blowing / starter not turning problem.

Also on a completely separate issue, how much of a load do these fog lights put onto your charging system? You engine battery charging circuitry probably can only keep up with about 35 watts of lights (about 3 amps) - including any existing headlights. If you put more load than that the charging system will not be capable of keeping up and the battery will be drained while your riding. So one of the things you will need to do at some point is measure the break even point on your charging system to see if these lights will work for you at all.

This is easy to do with a meter but lets get the engine starting with the electric starter first .