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bad boyz racing
September 3rd, 2012, 05:26 AM
How do you go back from a COS 3 to the original operating system? Do not have the tune file for the original operating system. Can i flash a tune with the original operating system then do a enigine and transmision segment swaps?
joecar
September 3rd, 2012, 02:58 PM
You can full flash the base OS, then do a cal-only flash from the latest COS file...

e.g. 02020003 is based on 12212156.
joeygc5
September 6th, 2012, 05:28 AM
How do you go back from a COS 3 to the original operating system? Do not have the tune file for the original operating system. Can i flash a tune with the original operating system then do a enigine and transmision segment swaps?
Yes, I've done it before when people went back to mostly stock. Just find a tune file with the needed os, perform a full os flash it in of the gm system, then do a same os trans segment swap and your golden.
joecar
September 6th, 2012, 06:59 AM
You can full flash a base tune having the same transmission...

or you can full flash a base tune with a different transmission and then do the transmission segment swap...


you will still have to do a cal-only flash from the COS file to get the modified tables into the stock tune (and you then also have to edit B3605 back to stock).
tinindian
July 8th, 2013, 05:25 AM
I have loaded COS5 successfully but now I want to revert back to the original 12212156 OS. But when I load my last tune file (the one with 12212156) the option to flash PCM and OS is grayed out. I have the commercial scan & tune version.
ScarabEpic22
July 8th, 2013, 06:20 AM
Plug your FlashScan into your laptop prior to opening any tune file, then you will have the full flash option available. If you have a V2, Id suggest using V8 to flash.
tinindian
July 8th, 2013, 01:23 PM
Plug your FlashScan into your laptop prior to opening any tune file, then you will have the full flash option available. If you have a V2, Id suggest using V8 to flash.

That worked, thanks!!!!
ScarabEpic22
July 8th, 2013, 04:30 PM
That worked, thanks!!!!

Sure thing.
ScarabEpic22
September 11th, 2020, 11:08 AM
Yes, absolutely no reason you cannot, as long as the base OS is correct.
joecar
September 16th, 2020, 10:02 PM
+1 no problem.
Supercharged111
May 5th, 2023, 12:08 PM
How about to jump from one COS to another? I want to make 4lo work correctly. I already have a good working COS5 based on 12212156, but need to start over with a 6.0/4L80 tune based on 12212156, back to COS, and segment swap my motor and trans stuff back over. Is the fastest way just to flash COS5 on there again, drop in the 6.0/4L80 cal, and segment swap my motor trans stuff? I'd go out and try it right now but it's 20 minutes away at the moment.
nonnieselman
May 9th, 2023, 06:10 AM
Yep..
And then you can do a Compare in V8 and make sure all your tune is the same.
Supercharged111
May 9th, 2023, 06:12 AM
Nice. I'll probably kick myself for not doing this much, much sooner.
joecar
May 11th, 2023, 08:46 PM
:cheers:
Supercharged111
May 26th, 2023, 02:50 PM
Well I was gonna do it the way above. I even had a calibration cooked up, then had an epiphany: why not segment swap the system segment over and do a cal flash to my latest tune? Bam! 4lo and my speedo work correctly. Why oh why didn't I think of this years ago? Probably because I don't have a real need for 4lo (and because I was able to cheat with my 2wd converted to 4wd trans), but I recently bought a truck that will and needed this as a proof of concept. All trucks will be based on 12212256 going forward.