okay so here's some quick background info:

last week i flashed my ECU with an old tune from my previous Evo, but i forgot to save my current Immobilizer code. i ended up disabling my immobilizer and my car started up fine.

my current problem:

i drove my car to class and after i got out of class (6 hours later) i tried to start my car and it wouldn't turn over. i checked the fuses and my battery is only a couple weeks old (Optima Red Top). i tried to reflash my ECU, but it won't let me read/write anything. it just says "no response to any known code". i tried using ECU Unlocker, but that didnt work either. it was saying something like [FFFF] and then [FOFO]. then it would say "no response to any known code". i have no idea what to do right now. does anyone have any thoughts?

 

Battery. IX especially will lock you out if they see low voltage. Basically they don't want you flashing if the battery is about to die. Put a jump box on it and ecuflash should be working again. does it even try to crank?

 

yeah it cranks perfectly. i actually recharged my battery to full and tried to use ECU Flash and it still didnt work. i tested the Tactrix cable on another friend's Evo IX and it read his ECU with no problem. i'm getting a new ECU tomorrow. maybe mine just turned into a brick.

 

Try disconnecting the battery for a while, then retry your efforts.

 

yeah i'm gonna try to reflash my ECU while my battery is on the charger.

 

figured it out. fuse #8 kept blowing because of my front o2 sensor wire was grounding out.