So, I’ve found another option I’m gonna try. I found a 5.3/8l90 flash on the hp tuners repository, I’m gonna segment swap the o/s in my factory ecm to be pretty much a clone of what I need, and then I just need the correctly programmed Tcm and it should work.

You can try that, but I don't think it will work as there's normally a security section that needs to be written thats not part of the HPT file(it's in the eeprom) so if you can't get that off your original ECM then it will either need to be re-linked or just disable theft options! I am so down to ...

So today I tried another t87 Tcm, and I can read and write that as well.. but it’s a diesel program.. so what I have in my mind, someone correct me if I’m wrong.. I want to write ecm and Tcm with truck vin that has 5.3/8l90 configuration, then truck will throw theft light and I go in with hp tuners ...

WOW & it's not that cheap to do either & then even more if you need your VIN programmed to it! I’ve got a connection at the local Chevy dealer and if not I’ll buy an mdi2 clone and pay for a subscription and learn to do it myself. I have a couple more TCMs on the way to try, and as far as I...

ironduke wrote:8l90 needs to be unlocked to be able to do anything with it using h p t u n e rs.

I do not know of any other way, but I haven't looked into it whatsoever myself..

Only the t87a 2017+ need to be unlocked, t87 2015/2016 does not.

You might want to supply the original file of both setups to compare, but I don't think the software in the ECM would cause an issue with bootloader in the TCM. I am going to try another Tcm, I got this one used and is probably muffed up.. I’m hoping that’s the issue.. I’ve been through absolute he...

I’m new here please bare with me... I have a 2016 GMC Sierra that I have a good bit of work done to, it came originally a 6l80 truck. I have swapped the trans out with all supporting parts to an 8l90, for performance purposes only. I have everything in and I’m having issues reading and writing the T...