motorbike kill-switch

Hello, I want to implement an arduino with my motorbike, and one of the things i need to do whit it is to shut down the engine.

The bike has a kill-switch for shutting down the engine. The kill switch, when pushed connects one wire(coming from ecu) to bike ground.. I measured the voltage between this wire and ground, and it is up to 8V when the engine is in high rpm. I then used a ammeter to shorten the wire and ground with the engine almost at full rpm, and the current was 60mA, and the engine shut down of course..

So i need to build some kind of hardware to make this possible, i think that using a reley is not an option because i need to shut it very fast and precize, and this is a kind of dirt bike so there is a lot of vibrations and shocks, and i dont think that this is too good for a reley..

Is there any way to do this?

thanks for your time!

I really wouldn't do that. If there is already a switch there, leave it alone. Don't add complexity, and associated risk of failure, to an critical function.

I don't want to remove the stock switch, just add a possibility to shut the engine with arduino too...

Okay - Kill switch as wired is a safety, and it is not recommended to remove.

You could get a transistor and connect it to the kill switch and ground and see if that brings it low enough, or you could use a relay. If you want the relay to work as a failsafe then you want the Arduino to energize the relay for the bike to run. That would be using a set of NC or Normally-Closed contacts wired in parallel with the kill switch. If the relay is not energized the contacts are closed and the bike won't run.