E78 Operating System Issues

Stock (Cruze) OS: 12656286
Stock Service Number: 12643636
Stock Tune: Attachment 17155

Replacement ECM OS: 12654014
Replacement ECM Service Number: 12643636
Replacement ECM Tune: Attachment 17156

Here is a comparison photo of the two ECMs:
Attachment 17154

Here’s the story: I have a 2014 Chevy Cruze with the LUV (1.4L) and a decent tune sitting on my computer waiting to be flashed. I purchased a brand new E78 ECU with the same service number (12643636) assuming that I would be able to full flash to my car’s stock OS and the tune I have written for it.

The ECU showed up in the mail today, I installed it in the car, and read out the OS (mainly out of my own curiosity). It came with OS 12654014 (New ECM Stock.ctz, attached), which appears to be for a 6.0L. It came without the VIN programmed, which makes since because it is a new ECM.

Curiosity satisfied, I proceeded to license the ECM to my V2. It is important to note here that I attempted to license the ECU using my Cruze’s OS 12656286 (E78 Stock.ctz, attached). It returned the error $0540: Incompatible Operating System (see screenshot below). I could see this being an issue if I were attempting to do a cal flash, but I was attempting to license the controller through the full flash option.

Attachment 17153

I opened the OS that came on the ECM (12654014) and selected the “Check License” option. Everything checked out fine and the terminal indicated that it was eagerly awaiting my license (see screenshot below).

Attachment 17152

The source of my concern is this: I don’t know for sure if my Cruze’s OS is compatible with the new ECU I bought, even though the service number is identical. I don’t want to license the ECM to my V2 and then not be able to flash in my Cruze’s OS and flush the $125 down the drain (unless anybody wants to kindly donate a 6.0L to me :D ).

If I license the ECM, will I then be able to flash in the other OS, or will it remain “incompatible”? If anybody has any advice or experience with this please let me know. This is my first time doing an OS swap on a newer GM ECU. I’ve only dealt with LS1B and Duramax PCM/ECMs in the past and I don’t want to screw anything up.

i think you will find your going to need to get a tis2web flashed into it with your vin, there is parameters that efilive does not change even on a full flash that can only be done with the factory flash option.

I'm in the same boat for the e83. I'll be doing that this weekend.

I hope I don't need a full factory flash. I don't know anybody in my area with a Tech 2 and the local dealers are less than helpful when it comes to doing anything out of the norm. Even warranty work is painful.

I have swapped operating systems on LS1B PCMs without issue before (from a 4.3L V6 OS to a V8 OS) and have successfully segment swapped portions of OSs as well. I also have swapped Duramax operating systems, but they were all intended for the same engine instead of going from a V8 to a L4 like I'm trying now. I am not sure how that works on the newer ECMs.

The main question I have is this: If I license the new ECM to my V2 will I be able to swap to the 1.4L OS or will I be stuck with the 6.0L OS? I'm sure there's somebody out there who has done an OS change on an E78, but I'm not willing to gamble the license to find out.

Your 6.0L E78 will need to be flashed with a Tech2 or equivalent, to load the base 1.4L calibration. No tuning software can write the throttle control portion of the OEM calibration. The Gen IV controllers are very different from the older controllers - and not nearly as user friendly.

Exactly what Taz said, TIS2WEB is the only option if you are dealing with brand new ECM's for E37, E38, E39, E67, E78, E83, E92 (I think E40 too). There is a special part of the ECM (actually it is a second CPU) that is program only, it cannot be read, when you TIS2WEB the ECM GM gets the correct throttle CPU file from their database and flashes it in. Only GM can do this.
Aside from that other things need to be configured, clutch position learn, misfire learn (CASE), new late model ECM's are a pain.
Once TIS2WEB has flashed your new ECM you should have no problems with EFILive tuning it. Something to keep in mind, these ECM's keep a tab on the miles the vehicle covers, turning up to your 10,000 service with an ECM that has logged 4,000 miles might ring some alarm bells.