My 78 175 HP Blackmax does not have a kill switch.. A lanyard can be attached to a tab on the ignition switch that will turn the switch off if pulled. I would like to install a kill switch. I have been told to ground the Black/yellow wire to kill power to the packs. There is no black/yellow wire attached to the packs. I believe that the orange wire which is common to both packs is the kill wire, am I correct? This wire goes to the ignition switch. If this is the correct wire, can I install a kill switch in series with it?