head unit setup

I have a 2003 infiniti M45, and it comes stock with a **** tape player... I have a new headunit I want to install but its not the usual wires in normal harnesses. I have tried to install it without an interface unit, since I cant find one anywhere. PAC audio, Scosche, Metra... nobody makes any...

I just got a kenwood ddx418 touch screen stereo. Its going in a 2004 grand prix. I have all the colors matched up but it wont power up. Theres a flashing red light on the front but the screen wont turn on. Ive tried a few different combinations of the wires. Theres a few wires I think could be...

My head unit's manual only had diagrams for normal mode, 2 way mode, and 3 way mode, which I am attaching photos of. My question is how specifically do I run it the way I have it shown in the other picture?? With the complexity of systems today, I'm sure this is doable but I haven't found...