Originally Posted by
Sinister Performance
2018 Silverado K1500 L83 6L80. Installed a used/junkyard ECM from a different 2018 Silverado and reflashed it using TIS2Web. That went fine.
Used TIS2Web to perform the IMMO Relearn for ECM replacement. It has me turn off the key, then turn it back on. It begins a 12 minute countdown, but after 10 seconds or so, it asks me if I want to perform a "health check" of the IMMO system. Doesn't matter how I answer the question, it returns to the countdown clock which is now at 11 minutes. After about 20 seconds tick off, it says turn the ignition off. I do that and get a 3 second countdown clock, then it says turn it back on. I do - and that's when I get the FE03 error code saying the ECM is locked.
I tried pulling the fuse for the OnStar module, Human Interface Module, and the Human Interface Bypass Module per suggestions from a friend who works at a GM dealer who says those modules could be "waking up" during the IMMO relearn causing problems, but pulling these fuses had no effect.
Has anyone ever run into this?