View Full Version : reflash to previous OS

December 17th, 2009, 08:00 AM
Hey guys is it possible to reflash to the previous OS? Im asking because for the 02 trailblazers with the latest calibrations has a bug in it (shifting problems) and the dealer cant tune back to the previous OS since the previous OS cant be selected as an option on their tuning software. Is there another way of doing this? Thanks

December 17th, 2009, 08:39 AM
Only if you can do a full flash , think the P10 can't do full flash (unless they have rectified that) , or find a PCM from a Bone Yard (Wrecking Yard) that hasn't been flashed yet .

December 17th, 2009, 09:05 AM
but even with a junk yard pcm with a different vin #? I thought we cant override pcm with different vin numbers?

the dealer thinks he can do chevy366 way as well but is not 100% sure. just trying to get some opinions just incase i dont make the right move.

December 17th, 2009, 11:39 AM
Contact Jesse and see if he can help you out , he may have a PCM you can swap for .

December 17th, 2009, 04:18 PM
he said he can do it which is a releve! but he thinks the 02 bug problem has nothing to do with the updated calibration but ill still do it just for sure. thanks

December 18th, 2009, 02:47 PM
You know from my other thread that Im pretty sure the bug is definitely an calz issue and not an OS issue. Think there's a bug in the code that edits the incorrect part when you change those 3 pesky tables.

You can run a PCM with a different VIN, not a big deal. Should fire right up after the security relearn, you can do a VIN change too if its a big deal.

December 19th, 2009, 02:09 AM
yeah but if you said this only happens to 02s and changing those three calibration back to stock then we cant even adjust those values to the max.

ill try getting an old pcm and will see how it goes.

December 20th, 2009, 04:06 AM
its weird but i havent realized it until now but ever since i got the latests tune the passenger side efans never spins which is why i have been getting some overheat engine lights up with low coolant levels...(not good)