Write fails everytime in 2003 Yukon Denali

[HaCKoWeLL]

Everytime I try to write in the vehicle OBD2 port it fails after bootloader. Scnner mode works fine and Reading ECM works fine everytime. I made a harness to flash with because the first fail left me unable to start my vehicle. If I unscrew the blue plug and plug in my homemade one in the vehicie it writes fine even without unplugging the green one. Still this is a pain in the ass. I do not have the stock radio but turn the aftermarket off. I turn off AC etc. It isnt voltage as I have 2 batteries and after using a power supply to flash the first time it failed I figured out I didnt have to remove the ecm from the truck and could just tap onto the stock battery for power with my harness. Please someone explain this to me, as it makes me very worried to flash it. Basically my Homemade harness has Blue connector, a power switch to orange wires, groudn to black/white and the purple wire from junkyard obd2 runs to green on pcm blue plug(pin 58). what could be interupting the signal on such a simple 4 wire setup? Can I splice a switch in for toggling between 2 obd2 ports and put one under the hood connected to only these 4 wires just for flashing?

[2xLS1]

Aftermarket radio or aftermarket remote start on the vehicle?

[HaCKoWeLL]

Aftermarket Radio, no Canbus adapter. I work in the mobile electronics industry and dont care about RAP(Retained Accesory Power) so I added my own relay for it, because I had the BOSE from factory and bypassed all that with amplifiers. It doesnt have remote start but it does have SWC(steering wheel controls) by Maestro. Radio is turned off when flashing, as with all other accessories.

[HaCKoWeLL]

I also pull the RTD fuse for ride level control and the air pump for suspension and that doesnt help either.

[5FDP]

Pull the radio fuse itself and see what that does for you.