2005 CTS-V PCM Bricked.

[Andy0x1]

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?

[Andy0x1]

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.

[Bill@HPTuners]

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.

[Billf6531]

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

[Chris@HPTuners]

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...