i have fitted afew of the double switching type
they are a pain sometimes the engine wont turn off if connected to alternator
best spot to turn off power is power tp the coils this will instantly shut the engine down
i try to not put it to any ecu wires
another thing i use is a tachometric relay it works of rpm signals
if there is an rpm signal then it will turn on a relay and i use this for fuel pump
so if the engine stalls the pump then stops these are used on most race cars that run old style sytems
any efi system has a way to control the pump to meet standards
thats if the person has wired it up right
