my son's falcon 90 will not start with the starter button. i replace the siloniod and start button assembly.how can i tell if the key switch is bad? i dont want to change the wiring harness if i dont need to...help!!!!

 

please check the back of the ignition/starter switch. these quads are notorious for the wiring to come apart. pull/tug on the wiring and then attach them back together. this is a common problem.

 

All quads have a starter motor interlock of some sort that keeps you from turning the starter motor unless the brakes are applied, the transmission is in neutral, the clutch is pulled in, or some combination of the above. It's the same idea as your car (where you can't start it up unless it is in neutral or park), and for the same reason - you don't want the quad to start and then lurch into someone or something unexpectedly.

I don't know your quad. Did you have to apply the brakes to start it before? If so, turn on the ignition switch and apply the brakes. Does your brake light turn on?

Changing the wiring harness would be the last resort in my opinion. Its a lot of work, and there are often incompatibilities that add even more problems -and often without solving the original problem either.

A better way is to get yourself a meter and use it to find the original problem then fix it directly. If it is a bad wire then cut it loose and run a new one.

On your starter solenoid there are two small wires going to it. Turn on the ignition switch, satisfy the safety interlock (like apply the brakes for most chinese quads), then measure the DC voltage on each solenoid small wire:

1) Wire one with the starter button left alone.
2) Wire one with the start button pushed.
3) Wire two with the start button left alone
4) Wire two with the start button pushed.

These voltages will give some clues as to what is going on.