key fob programming not working?

Yes, it could be the fobs or the BCM needs to be replaced, I would start with a CAN scan, you can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is how to change out the BCM in the images below in case you need it. Also, I have included the security system wiring diagrams so you can see which fuses to test and how the system works. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

yes, i have AUTEL MaxiSys MS906 BT.

Those are good scanners.

The only codes I have are the throttle pedal code and throttle code.

Faulty ECU or controller: While it is possible for a faulty ECU or controller to cause programming issues, it is less likely in this case, especially if the rest of the vehicle's functions are working properly.

I purchased an OEM Key Fob and still cannot program it.

Did it come with instructions? some aftermarket key fob are better for programming FYI.

No. I purchased it online and the description states it must be programmed by a professional automotive locksmith or dealership.

I had also reprogrammed the ECU using GM Tech online software and still no luck.
Or is it the BCM?

Yep, the BCM is what holds the key and fob programming. Let me know what happens please.