pcmhacking.net

i managed to brick one in a VX today, trying to get rid of VATS so he can move the car, they lost the key.
i had a spare PCM VX so I copied the dudes original BIN off his PCM, 3 times, and the CAL
i took his PCM out, put the spare PCM in.
i then flashed that PCM with his BIN and CAL no issues there.
i then went and flashed the enhanced bin for the VX auto on there.
it went thru and wrote bank 1,2,3 no problems, then, prompted me with re-writing the checksum, i said cancel to leave the checksum. it then said if you cancel you risk bricking, so, didn't cancel,
it then re-wrote it again, bank 1,2,3 no problems. it then prompted for re-writing the checksum again. this time i clicked OK update the checksum, then i got a message about a failed write.
could no longer link to the PCM.
dash also only displayed 'error'
i put their original back in all good, back to no start but that PCM is readable etc.

i've clearly got something wrong here, i've never ever done this before, thoughts /ideas very welcome. would also be keen to know what chip to unsolder on the board (i've a hot air station etc) so i can unbrick it. keen to have another go and see what the go is here.

Sounds like you weren't using the latest flash tool as I think it does checksum fix before first write(a featured I pushed a few years ago, to save extra time writing).
But aside from that there should be a version out there that will un-brick a non responsive pcm VL400 did it a few months ago but never got released!

Well the starter motor wont operate without a key as BCM Security wont match. You can access the PCM but will be hit and miss due to security from BCM messing the bus.

i always tick "Flash PCM Autofix Checksum" in the options, i think latest version has it on by default and dont have any issues. Normally if it looks bricked after a BIN write a power cycle will start it up again, given no other issues.

If you dont want to update the checksum then set the Software ID to AA0A instead of BD0A to disable checksum checking.

The lastest Version 1.51 has VX/VY Flash PCM recovery in the Tools menu which you can try.

The chip on the board is a PLCC AM27C010 you can desolder it and write the whole bin to it then solder it back on.

Thanks lads. Will have a go at the recovery.

turns out no need. their connection came thru, they have some 'software' which takes the number off the BCM and then pairs the key fob to it. i'll try and find out more details.

A second hand fob that’s previously been programmed to another car???

yes biggVL. some dudes in sunshine. 80 bucks. no tech 2. number off BCM went away to a 'van' and gave them that fob back in ignition and go. WTF i didnt think it was possible. they asked how and he said i have special software, would not disclose.

key fobs have a write once serial eeprom chip in them, So he would either have to give you a new keyfob or replace the chip with a new one with new code on it. Did they connect in the car at all?

no. he didn't connect anything to the car at all dude. nothing to the OBD2 port. no removal of BCM or PCM, just the BCM number. i cant see how that would work, for 80 bucks it would have to be minimum of a new FOB and connection to car ala tech2. waiting on the young fella to wake up so i can have a chat to him, he gets this stuff more than his old man.

some locksmiths use something like this, but still need to know the code which can be read from an existing key to then clone to a new one.
[youtube]https://www.youtube.com/watch?v=1lVSszSn9tg[/youtube]