Has anyone ever had intermittent problems with the engine stop switch? Why does this even have one right next to the ignition switch?

[2015 Z Force 800 53/Trail EPS]

Has anyone ever had intermittent problems with the engine stop switch? Why does this even have one right next to the ignition switch?

It's a requirement. You will see kill switches on all ATVs and UTVs as a secondary way to shut them off in case of a fire or roll-over event. And yes, as they are not a water proof switch, water can and does get down inside and corrode contacts.

I had an occasion this summer where I accidently hit the kill switch and after setting it back, the engine would turn over but not start.  After a few flips back and forth on the switch, the machine roared back to life. I committed then to have the switch replaced.

Today I removed that switch and explored it with an ohm meter. One set of contacts was 100%, while the other set had values of resistance from 30-80%; clearly no bueno.

I took the switch apart and found it was clean with no corrosion. No signs of water or dust intrusion (and I use a pressure washer after every ride!). The wires were soldered and sealed to the switch. The build looked solid and everything looked good, so what could the problem be?

The switch has two spring loaded rollers that roll over the contacts flipping them from one side to the other.

I can only presume that the spring on the fuel injector contact side was weaker than the spring on the starter relay side, or that the fuel injector side would stick, failing to return and put full pressure on the contact. Either way, it wasn't making a consistent connection, and that multiple switch throws finally made a solid connection allowing it to start.  This got me to thinking ....

This machine has had an issue since new. Every once in a while, often when climbing rocks or otherwise bouncing the machine around, the engine would stop dead but then start right back up. Other people have complained of the same behavior with their Zforce machines and no one has ever identified the cause.

Well, this switch, with its marginal contact force, is very likely the cause of that intermittent issue. All the evidence fits.

I'm going to hard wire the harness bypassing the switch for now, until I can find a better more reliable switch.

I also found that the harness is wired for lighted switches, and the switch had lights built in, but that the connection to light the switch was broken or disabled at the side contact spring.

[2015 Z Force 800 53/Trail EPS]

Yet another example of Chinese electrical components. I found..(believe it or not)..that even in some simple connectors there is..or can be resistance. Found several on mine where there is enough resistance to read an actual voltage drop through the connector. And like yours, an inspection doesn't show anything that jumps out. 

Looks like the DORMAN 84944 is a proper replacement rocker switch for the Z8's kill switch.

Now to decide if I want to solder it into the harness,  use spades, or just bypass it all together.

[2015 Z Force 800 53/Trail EPS]

Looks like the DORMAN 84944 is a proper replacement rocker switch for the Z8's kill switch.

Now to decide if I want to solder it into the harness,  use spades, or just bypass it all together.

I just spaded all my extra switches knowing none will be in there for ever. Already replaced my CVT fan switch cause of water. Probably never need the kill switch but ...you know how it goes. "Better to have and not need...then to need...and not have"