4AGZE ECU burned tracks

[tooch]

I think I may be getting to the bottom of my idle issue!
Pulled the ECU out and opened it up for a looksie....staring me in the face is a big burnt ceramic resistor thingy, leading to a transistor or mosfet or something. The track looks very burned/blown. I traced it to the terminals for the wiring loom....sure enough it leads to RSC which is one of the ISCV terminals

Now here's the thing, my idle bounces whether or not the ISCV is unplugged or plugged in. Only does it when the engine is warm, and IF the ISCV is plugged in, the bounce is slightly faster. I swapped the ISCV for a different one so it's definitely not that.

What I want to know is what would likely cause something like this? I tested the old ISCV and it still opens/closes with 12v applied to the pins, and the resistance on both old and new ones is within spec so I wouldn't think it has shorted and killed the ECU. Is it possible that another component within the ECU may have failed and caused this output to fry itself?

[tooch]

Thanks to Drifty Midship, I have done some more troubleshooting. When I apply 12v straight to the ISCV to close it, the idle settles perfectly!

So if I can find a cheap ECU i'll buy it, otherwise I'll just wire in a switch to send 12v into the ISCV