[Hi Stan,
Hi Joe... the manual for the REAL TRAX 031 switch. The diagram on page 14..]
I now see what you are referring to. I see this would work in conventional, but in DCS the engines will startup in conventional because of the watchdog signal being present only for 5 seconds after the TIU channel receiving power. Of course you can either repower the channel, press the start up button or use Barry's trick to make the engine come up silent.
Learn something everyday.