I'm at the switch installing phase so revisiting this topic. Still thinking of the multiple switch concept but I've updated it a little. Been reading some more and discovered "latching relays". Didn't know about these before. It's different than a regular relay in that once it's been energized and the contacts closed (or opened) they will stay closed (or opened) even after the energizing power is cut. You then have to re-energize the relay to change the state of the contacts. If it's a dual coil relay you energize a different coil to break the contact. If it's a single coil relay you reverse the polarity of the energizing power to break the contact. I read about another type that uses a cam arrangement but not considering those.
Back to the original idea of four DPDT on-off-on switches. 3x3x3x3=81 possible combinations. Three of the four switches are wired to complete different "kill" components such as inertia switch, brake pedal switch, rear brake light, starter solenoid, PCM relay power, etc... There's a lot to choose from. So three of the switches have to be in whatever is the "on" position for that "kill" component to work. The fourth switch most stay in the "off" position.
This is pretty much where I was before when writing about shorting out a fuse if one of the switches is in the wrong position. The problem with this idea is the thief gets more than one chance at setting the switches. In my case there is a bigger problem in that I can be both klutzy and forgetful. Yeah I know, go figure. Anyway there is always the possibility (probability) I will accidentally set one of the switches wrong and end up replacing fuses. Also what happens if I reach down while driving and hit the switch. Do I accidentally kill the engine at a really bad time (middle of the Chesapeake Bay Bridge)?
This is where the latching relays come into play. Each of the kill components has a latching relay in series with it. The relay is NC (Normally Closed). If any of the switches are set into the wrong position the latching relay will open and stay open. To prevent accidental triggering while driving the power to the "opening coil" on the relay comes from the starting circuit. So accidentally hitting the switch while driving will have no effect.
By using dual coil latching relays the power for the "closing coil" can be separated from the "opening coil". Since the closing coil isn't powered from the starting system even if the thief sets the switch back to off or into the correct position it doesn't matter. The latching relay has been set to open and can't be set back from the starter so he gets
exactly one chance to get it right.
So let's say you've accidentally set one of the switches in the wrong position and tried to start the van. Now one of the latching relays are set in the open position. What do you do? You go to wherever in the van you've hidden the reset button for all the latching relays. When you press this button it will energize the "closing coil" on all the latching relays. This will reset all open relays to closed. If the relay is already closed it doesn't do any harm. This reset button should best be located nowhere near the drivers seat. If we were talking about a car I'd suggest hiding it in the trunk but with a van there are endless places it can be.
OK that's my latest idea. It still needs some refinement but hopefully it makes sense. I haven't tried it out yet, and even if I did wouldn't tell ya'.
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