thought #1: this ECM doesn't use 'short a to b mode'. that's for 80s stuff. for the 8051 all you need is data, ground. that's all. two pins on that diagnostic cable.
thought #2: pretty sure...

you definitely suffer from confusion but that's normal for someone new to this

if you use tunerPRO (not tunerCAT) at least use my XDF file. nothing else will do this ecm justice for a 'new tuner'...

read post two of this thread

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?7116-1995-lt1-M6-tuning

he went ahead and built the flash tool into tunercat ages ago (same tool just built into the menus)



yeah there are a few tools out there, here's the actual breakdown.

FLASH: eehack,...

since you paid perfectly good money for CATS tuner (a commercial package) i'd suggest contacting him to figure out why you're getting that error..? it shouldn't be doing that. you're probably just...