power to ecu

[Did My Time21]

Okay, my corolla 4a-fe only runs intermittently and then i realized when the ignition swith is in the "ON" position occasionally, my check engine light doesn't come up. i got a diagram of the ecu harness on which terminals to check to see if i'm getting 12 volts but like i said this is intermittent. is this common? what wire does this lead to in the engine bay? is my ecu bad?

[Flashmn]

Might be the rear part of the ignition cylinder.