roccod787

2020 GMC Sierra Elevation: I had my battery unplugged yesterday for about 3 hours, and upon reconnecting, the infotainment screen won't finishing booting up, and is frozen on the GMC logo. Has anyone else experienced this before? I called the dealer, and they said it may come back on after driving for a while (but wasn't able to tell me how long) and said it also may require me to bring it in for service. That doesn't seem right; people change car batteries all the time, and shouldn't require a $200 service charge to reboot the screen. Does anyone have any tricks to get this radio to turn back on? I have had my battery unplugged before (although never for this long) and didn't have this issue. I also noticed the screen stays on/frozen even after shutting off the car, exiting, and locking, for about 3-5 minutes (which is also a new problem obviously related). Thanks for the help!

I'm going through the same thing as you did. 2020 Sierra Elevation. Stock cloth/manual seats. Upgraded to power heated leather in the front. The power works fine, but the heat does not (even installed the OEM dash buttons on the HVAC control). I also verified my truck as the factory wiring and fuses for heat. Nobody will help reprogram the BCM to allow it to communicate with the seat heater control module. So, the power will work in your passenger seat, but the cooling will probably not, and the rear heated seats will also probably not work. Let me know if you find a way to get it to work, or a dealership to help reprogram. I've called at least 6 GMC/Chevy dealer who all tell me it can't be done.

3/7/2023: Took the truck into GMC today to find out my truck does not have the complete/correct wiring from the dash to the seat, which is why the user control buttons don't illuminate when pressed. I've contacted harnessdr.com to see if they can provide the retrofit wiring. Will post here once I find the solution. 3/11/2023: I took apart both driver/passenger side harnesses today, and turns out I DO have the correct wiring. Every single male pin on the seat side harness matches up to a female connector/wire on the truck side harness that runs to the BCM. Seems the dealer either 1. Was not wanting to mess with BCM factory settings, or 2. I need of glasses. Didn't stop them from charging me $192. I also confirmed my truck has both fuses, F6 and F17, which were factory installed, that are specific to front heated seats, option code KA1. I've contacted another shop (non-dealer) who has the tool to flash the BCM.

I replaced my stock cloth/manual seats with OEM powered leather heated seats in my 2020 Sierra Elevation from another GM (same year) truck. Plugged right into the old harness, and the power function is working (moving the seat forward/backward etc). I also installed the new climate control user interface on the center dash so that I now have the OEM seat heater buttons. Problem is nothing happens when I press the seat heater button. I've checked the fuses and all good there. I read online that the dealership needs to reprogram the BCM (Body Control Module). Also noting I do not have the digital heated seat controls on my stereo screen like the trucks with stock heated seats do. One GMC dealer is telling me that for $200 they will try to reprogram the BCM, but cannot guarantee it will work. Has anybody done this before? It is as simple as telling the car "enable heated seats option" so that the BCM will recognize the new buttons in the dash? Another GMC dealer I talked to won't even try to reflash the BCM because they don't believe it will work, telling me the BCM's are VIN specific. If that is true, I am wondering if I will need to give the dealer a VIN from a similar model that does have stock heated seats, essentially tricking the computer to allow it to upload the correct options. PS: Same issue with the trailer brake controller. The center dash I pulled from the other sierra had the controller as well, so i swapped out my blank plug with the controller (all the wiring was there behind the dash) but nothing.