ECM memory wire and kill switch pie in the sky theory.

I was thinking that absolutely everything had to shut off, but I re-read the rules.

Tech inspectors may not like it though.

Radiator fans are audible, ECMs are not...  YMMV.

I understand.  Since this is, more or less, potentially a safety issue. since there would be a 12 volt wire live in the car, I can see where they wouldn't.  I would like to hear the judges perspective on this though.

Way ahead of you.  I've got a 100 amp fuse set up on it.  My car audio days of my youth and my half arsed college "edumacation" are coming in handy, barely.

The memory wire requirements are very small for an ECM but it does need 12 volts.  Instead of doing the battery thing with a transistor circuit to keep it alive, I could probably just put a big capacitor there across the 12 volt and ground rails to keep it alive.  That being said, it likely doesn't drain that fast anyway.  I think it takes around 15 minutes to fully bleed out based on the residual stored charge in any system.

I see the reasoning behind it, but looking at the schematic, I don't think this is absolutely necessary because the ECU is on the same fuse as the ignition switch.  The kill switch is breaking ignition and in essense, leaving this lead isolated, so it's not really competing with anything else.  Of course, if it were, that would certainly be a consideration.

EDIT: Just to make my last explanation clearer than mud, where we are breaking the circuit, for anyone interested, is before the ignition switch.  This break cuts off flow to both of the ECM and EFT computers, right after the fuse box (anyone with a 'Yota MR NOT, the AM2 fuse), in addition to shutting down the main engine relay feeding the ignition circuit.  That's where the constant 12 volt power is coming from, not after the ignition switch (Yes, I shook my head at my own explanation)

Indeed.  The main fuse is 100 amps.  There's no need to do double duty (doodie?  Haha! I said doodie!  Ok, I'm back now.) on what the car's fuse block is already doing.

Standard killswitch wiring for Lemons is as follows: Four terminal, (two pole) killswitch. One channel across the battery. This will kill battery power. Another channel on the ignition circuit (The one coming from the ignition key will do the job). If you were ambitious, you could do the same thing at the distributor, or anywhere else in the critical path from power to the spark plugs, but the graceful way to do it is with the ignition line from the ignition switch.

By interrupting the ignition circuit, you kill the spark, which in turn kills the alternator without doing anything that wouldn't happen if you turned the key to the off position. Bottom line the battery isn't supplying power and the alternator isn't supplying power.

My thoughts on the ECM are as follows: Fuckit. Too much work to care about keeping power to its memory circuit. If your car is in the kill position for more than like 5 minutes, it's probably legendarily broken anyway, and forgotten ECM settings aren't going to make anything any worse. If you're paranoid and store the car overnight with the killswitch in the off position, just run it around the paddock to relearn in the morning. If your ECM doesn't keep its memory alive for the few minutes here and there it's killed (tech kill test, and during fueling are the only times it's required to be dead AFAIK), it's probably the LEAST of your problems.

If you still need help wiring that shit up, I once wrote a really patronizing explanation that I'm pretty sure a 5 year old armed with a wiring diagram and screw driver could pull off.