The vehicle is a 2004 GTO with a 5.3. I have attempted in the past to read the PCM but it appeared to be locked. Since that time, the owner has fabricated and installed a turbo kit and he's asked me to tune it.
Last night I tried doing a Full Flash of COS3 (04110003) thinking that I wouldn't have a problem with the PCM being locked since I was overwriting everything. The bootloader was rejected repeatedly. I tried every combination of high/low speed and ALT Keys, connect/disconnect, and ignition cycles.
One footnote, I typically don't license the PCM until I know it will actually read and write properly so that a license isn't wasted. I will normally start the flash process and wait for the message to appear asking me to license the PCM. In this case I never saw that message.
Details:
PCM Service #: 12586243
V7.5.6 (Build 133)
Bootblock: 2.06.03
FW: 2.06.41
As you can imagine the owner is quite anxious to hear the car run for the first time. Hopefully someone can help me make that happen for him
Thanks,
Brad