MicroSquirt.com read only forum (Jan.15,2018)

For the same reason you can't feed the VR signal directly to the processor - the chip doesn't understand an AC signal, and the voltage swings are sufficient to fry it. The VR circuit is a filter / pre-processor, that turns a dangerous AC signal into a 0/+5vdc signal that the processor can accept and understand. The knocksense is the same thing, set up for a different input.

Ok, thanks for explaining. I'll look in to the knocksense to see if can work with a Toyota sensor.