I bought a 03 GT used about 2 years ago and have been modding appearance and this year decided to do power upgrades. I bought 373 gears and an SCT X4 tuner. Installed gears but can't flash PCM. XSH2 is the code on the PCM. I have checked the wiring at the PCM and Data link port and it appears to be ok. Connectivity and in the correct position on both ends. To be clear The SCT tuner says Cannot read veh ID Error #11020. Tuner is up to date as of today. OK so to what I have tried as far as diagnosis.
1. Called SCT they said wiring problem.
2. Checked and confirmed continuity and connector pin location (correct) as far as I can tell from browsing the internet. (cant find anything specific to my year)
3. Plugged the tuner into a different 03 GT (reads Veh ID no problem)
4. Had a different PCM installed in place of old one. Still get an error.
Don't know where to go from here.
Any suggestions or help please
What does the cluster do at key on? All Dashes? If so, consider the possibility that the problem is that the PCM is NOT getting power. That would also explain why the replacement PCM didn't talk to the tuner either. Bonus. No power would also explain why your new tuner isn't able to flash.