2005 CTS-V PCM Bricked.

OK, so it started off that I couldn't "Read entire" PCM without the Nav system cycling.

Removing the Onstar / Audio fuse resolved this and I was able to complete the read operation.

Since then, I have re-installed the fuse, and with the fuse in place, wrote a calibration. This worked fine.

I made some additional changes, and wrote a second calibration just fine.

Didn't like how it ran compared to the first change, so I started writing a 3rd tune to the PCM when it hung-up 70% through.

The Nav started cycling again, and after a few min with it going no where, I pulled the fuse again.

It didn't help this time, and now I lost communication with the PCM and it won't even try to turn over.

I pulled the battery, waited, and re-connected it. Tried a write entire (Non-Active Test Write) it gets to about 50% and stumbles, but eventually makes it through. However the checksum fails at the end, and the car still won't turn over or do anything.

Hooked up a battery charger to make sure that wasn't an issue, but no go.

There is a faint high pitch noise coming from under the hood that I've never noticed before, not sure if it's related.

What now? PCM Fried?

Update, after several failed attempts, Just for the heck of it, I tried performing a Write Entire with the "High Speed" option Disabled. The write was sucessful this time, and the car is running again. :worship:

FYI doing a write entire to "recover" a pcm is a surefire way to fry it. Once you try a write entire you cannot go back to a write calibration only to try and recover the pcm so is not recommended. Glad it worked out in your case but you really caught a lucky break IMO.

I suggest you leave the audio/nav fuse out until your tuning is finished, and no further full or calibration uploads are contemplated.

The NAV/Radio is definitely the problem, leave it disconnected at all times while tuning.

The issue relates to some non-compliant components that do not remain quiet on the comms bus like they are supposed to. This chatter during reflashing causes a lot of problems.

Do not use a write entire to recover anything, as Bill said chances are you will just make a recoverable issue, not recoverable.

During regular tuning you will never need to perform a write entire.

Glad it worked out for you this time :)

Chris...