5.3/4L80E with E38/T42

working on an LS swap in a 69 camaro. Had a PCM from a 09 express van 2500 as well as an unknown junk yard T42 TCM. after trying to change the trans values for several hours I could not get it to take changes. As soon as the car would move about 30 feet the trans was already in 4th gear with the converter locked. I assumed the TCM was for a 4L60E and attempted to write an entire 2008 van 2500 file to the ECM and TCM and ended up bricking the PCM. I downloaded several files from the repository and none of them would allow a TCM segment swap thats why I went ahead with the write entire. I'm now out the cost of another PCM and credits for it.

I've done a bunch of GEN3 LS swaps but this is my first time dealing with a GEN 4 swap. What pcm/tcm is needed to make this swap function and shift right. I'm already loosing money on this swap I'm ready for it to be gone.

Can you Write entire the ECM? The T42 is pretty robust and usually takes any OS you throw at it.

If you can get the 09 Express van ECM working, use the corresponding T42 OS so you have a matched ECM+TCM pairing. Then start tuning the shift points, rear end, tire size, so it's driveable then dial the engine in.

The TCM seems fine its the PCM that got bricked. As soon as I try to write anything at all it gives me an error.

ok so new PCM in it now from a 2007 corvette OS 12614676 and the old TCM that properly took the 4l80 van file OS 24239927. So I should now basically have a 2007 corvette with a 4L80E right?

There is a mid-2009 breakpoint with E38s. Early ones have a 63lb injector limit, late ones 127lb. You cannot swap OS's between them. They have different service numbers which is a great big flashing clue that they have different hardware inside and do not interchange.

Also, using HPT for changing the OS between years/platforms is a big no-no on Gen4s. The TAC is built-in and HPT cannot access those segments. Use a Tech2/MDI or equivalent that can flash actual GM calibration files.

Noted... Like I said I'm new to the Gen4 stuff. I'm wondering if this 07 vette PCM will work with what is now a 2008 chevy express 2500 4L80E T42 TCM? The other PCM was a 09 express 2500 PCM that I tried to write a 08 express file to. I did a write entire and ended up bricking the PCM but the TCM seems fine. The TCM came from a junk yard from a 09 cobalt A4 but now has a 08 express 2500 4L80E OS on it.

2007 and 2010, just picked at random for being before/after the breakpoint, both list the same TCM service number. You haven't mentioned what ECM/TCM you have so it's hard to say 'yes, that will work'. Go someplace like Rockauto, make sure the service numbers for what you have match the OS's you want to use.

PCM 07 corvette 6.0
OS 12614676
service 12597121

TCM 2010 cobalt 2.2
OS 24239927
service 242521149348

The OS numbers were copied right from the HPT tune details window and the service numbers are whats written on the decal on the PCM/TCM cases

I can upload the tune file if it would help any. Thanks for your help so far I really appreciate your info good sir.

The new 07 Vette ECM will brick if you try to flash it with HPTuners to a different OS not compatible with the ECM hardware.

What we don't know is if the 07 Vette ECM you have will communicate with the Express Van 80E file. There are 07-09 4L80E TCM OS' available, BUT they may not communicate with your ECM properly. All Vettes were using the T43 with the 6 speeds in 07. Can't hurt to plug try the 07 Vette ECM and 09 Express TCM and see if the ECM throws communication codes.

The TCM has the 08 Express Van OS.

What error VCM Editor is throwing when you attempt to write the 09 Express ECM? It may be salvageable and would get you back to the correct ECM+TCM OS with minimal headache.

I did some digging, this ECM service number 12597121 was used with both Corvettes and Suburbans. There are a few cross reference guides on the internet, per them the hardware is compatible with the current 12614676 Vette OS and also the 12608677 Suburban OS. The Suburban comes with a factory 80E T42 OS of 24235341. So, I'd do some digging and you'll likely need to flash your current ECM with SPS, but you may be able to go to an 07 Suburban ECM + TCM OS with the hardware you have.

Doesn't the '2010 Cobalt' still showing in the details window for the TCM mean that the write-entire with HPT left some old stuff behind?

2008 Express van calls for a ECM service number of 12612384, which also crosses to a 2008-2009 Corvette. Different from your 12597121 (interchange with 12603892).

They may be compatible but if the SN doesn't match you're taking a chance of another brick. I'd either use an OS/platform that matches your service number, or get a service number that matches the OS/platform you want to use.

So if this vette OS doesn't like this 80E that 12608677 burban OS might be compatible with my vette PCM and work with my 80E?

2007 Suburban 2500 does indeed call for ECM 12597121 & TCM 24252114. Use VIN 3GNGK26K77G211058.

The only loss of communication code I get is U0121 for the ABS module. So does that mean that my 07 vette OS should work with my van TCM and 4l80?

would I be ok to license this PCM or should i find and download that 07 suburban OS and write that to my PCM?

You CAN NOT flash the Suburban file to that ECM using HP Tuners. Do not even try that.

Well, I mean, you CAN, HPT will let you do it. But you will not be happy with what comes out the other side. HP Tuners only lets you touch 6 of the ECM segments, there are 8 segments ('calibrations') in a real GM file. Not even write-entire will do it properly, we are locked out of the two where the ETC lives. You do not want to end up with a Suburban OS trying to make the throttle work with the Corvette ETC segments still in there.

Tech2/MDI/Mongoose/whatever real actual programming tool, plug that Suburban VIN into TIS, flash ECM, flash TCM.

I don't have access to either of those. My only option is HPTuners I guess my question is will this 07 vette PCM OS read and play nice with my 4L80E TCM? Or would I have to find a PCM from an express or burban for this to work?

I don't know what part of the world you're in, but any GM (or affiliated) dealer can flash it. Tow car in, they flash, you tow away to fart around and make it run somewhere else. Convincing them to do it is another matter, but they can do it.

These days more and more independent shops are getting the ability to do dealer-style reprogramming, it's a major drain to send every car that needs something programmed out to the dealership. The 3rd party scan tools of today are also more likely to have the capability for that very reason. It's become too common to keep it restricted to the dealership only.

Any tuning shop worth existing will have a bench harness to flash bellybutton E38/T42s. Lots of tuning/harness shops also let you mail in your ECM for programming for the very reason someone like a home-gamer doesn't have the dealer tools. There are folks here on this board who will bench flash your modules and send them back to you for a reasonable fee.

You can find programming services on Ebay (one example, I have no idea if this one is reputable or if there might be a cheaper option using more generic search terms: https://www.ebay.com/itm/254563254521).

Last, you can buy an ECM & TCM programmed to whatever VIN you supply. That particular E38 service number happens to be cheap as chips.

So, do you want to rethink that 'my only option' thing?

I'll be the broken record here, this is the reason why I've suggested trying to get your original 09 ECM working again. If it powers up and you can connect to it, you should be able to flash it back to the original 09 file with a Write Entire of the original file over the corrupt 08 file. What is the error code you get when trying to connect to it?

If you don't have access to a GM reflash tool, go with one of the options blindsquirrel mentioned. It's not worth licensing something in HPTuners that you don't know will work, you'll end up wasting more $$ in credits than buying a correct ECM (and TCM if desired).


HPT doesn't change the VIN of a T42 TCM to my knowledge, my hunch is the details provided earlier are based off the VIN in the TCM. If the TCM OS, segments, and checksums match the flashed file upon read, should be good.

I have now borrowed a snapon pass through that can do factory reprogram. Under that VIN it's giving me a few options but neither are the OSID that I have?