DIY Cruise Control FAQ (2006-2010 Yaris)

[CTScott]

Originally Posted by bobor

Unfortunatelly I do not have any experience with solid state switching. If you could point me to some good tutorial, I would appreciate it But AFAIK in this case, the input signal (voltage level) from either accelerator pedal (hall probes) or DAC would be somehow degradated (lowered) due to voltage drop PN junction.
Solid state switching is definitely faster than mechanical relay. But advantage of a relay is that it does not require power supply to interconnect one of the input lines to the ouput. I though of using this a safety mechanism, so in case anything goes wrong I would just switch off the power supply to cruise control module and the relay would (almost immediatelly) switch back to default state (direct connection of accelerator pedal). But if I find some good solution using solid state, I am about to change my mind.

Here's a pretty good intro to transistor switching.

http://www.kpsec.freeuk.com/trancirc.htm


Rather than switching back and forth, it may actually make more sense to put the microcontroller in between the pedal and the ECM. That way, the ECM samples the pedal outputs and then in normal mode, just emulates what it sees. Then, in CC mode it ignores the input and sends its own output.

The other advantage of this method is that you can improve the throttle response in normal mode (like the Blitz throttle controller does).