I think it is bricked

I recently bought a wrecked 2004 GMC Sierra with a 5.3 drive by wire Vortec, in preparation of pulling the engine to put it in an older car I licensed the Computer in Hptuners and disabled the parameters that I don't need in this swap as well as turning off the VATS; usually this is a drama free experience.

This time things went south, it took about 12 minutes to initially read the PCM (in the past it always takes about 2 or 3 minutes) which made me a bit concerned that something might not be right but I edited the file and tried to write the calibrations with my fingers crossed. The process appeared to complete but the final message was that it failed in spite of the complete progress bar.

I tried to rewrite it again with the original unedited file and it failed to complete, which sent me to the web for some ideas but all of those failed to bring this PCM back, as a last resort I tried a write entire with the original file and this also failed to complete and has left the PCM invisible to Hptuners, my Tech 2 and all of my OBD2 readers.

So I assume it is bricked, I have never had an issue like this before with Hptuners so I assume the PCM took a big shock in the accident (Front End Wreck) and it was just not quite right anymore, So now I am looking for a good PCM replacement and I want to understand the process before I buy something.

The service number on the bricked PCM is 12586242, there are many of these for sale on Ebay but some of the capability wizards say it won't match my vehicle (Although a couple say they are fine) so I have a few questions.

1: Is it true that all PCM,s which match my service number will work as long as they come with the correct OS for my 2004 GMC Sierra?

2: If I purchase a PCM that matches my service number but has the wrong OS is it possible to use Hptuners or my Tech 2 to flash the correct OS into the replacement PCM?

3: Am I right in assuming that even a "Write Entire" using my original flash will not replace the OS in a replacement PCM that comes with the wrong OS but is the correct Service number?

The reason I ask this is because there are several matching service number PCM,s at local wrecking yards that I cam buy tomorrow for 50 bucks, the ones that I found that match my OS and will come with the correct VIN will take about a week to get and cost a bit more; If I can get a good used one locally and set it up myself it would save me some time.

I am making a bench harness today to give my old PCM one more attempt, I thought maybe some wiring was damaged in the wrecked truck that resulted in my issues: I know this is a long-shot so I was hoping for some direction on how to buy a replacement so I can get a PCM ordered tonight if need be.

Sorry for being so windy!

You can definitely do it with the same service number but different vehicle/OS with Tech2/TIS. I did this with a Impala LS4 #12596679 and reflashed it to an Envoy LH6 #12596679. Those two even have several differences in the ECM pinout between them. It worked fine. In TIS2000 just input the VIN for the new application and it will pull up the right OS for it.

Thank you!
I have not used the Tech 2 to flash an OS yet but I will give that a try; the bench harness I made works well but not with the dead PCM I am replacing so it wasn't a damaged harness in the wrecked truck that caused the failures. I will pick up a matching one today at wrecking yard ;)

Well I found a wrecking yard ECM with the same Service Number and I got Tis2000 setup and running, I used an old Dell laptop from my junk closet because it had a COM port. I was able to flash the ecm with the latest version of the correct OS and the VIN from the truck that I am Cannibalizing, I installed the ECM and calibrated the crankshaft sensor without issue; the engine is running better than ever!

I have no problem communicating and editing the calibrations through the trucks data port with HpTuners now, I think that confirms that my issue with the old ecm was just damage from the wreck;Thank You blindsquirrel for pointing me in the right direction!

For future reference. Some GM ECM?s of this vintage have much more reliable results if you pull several fuses, or just bench flash every time. If you look up ?pull fuses Gm bullydog? you should be able to find the info.

bricked the one in my 04 gtp friday... first time that happened in well over 1000+ flashes....
did almost the same exact thing with the long read time.
thankfully an easy pcm to get a hold of

just updated hpt right before... hope that isn't the issue as I need to update the tune on the fresh ecu

New pcm still having issues. Cant high speed read... car resets mid may through slow speed and takes 15 minutes... scared to try to write again as last time it bricked my pcm.

I've flashed this and a few hundred other cars with the older software and never had a single issue... what's going on here?