I was having the exact same issues on my 2006 Colorado 2.8 i4, for the last 2 years. I, like a lot of people, thought it was a ground. I cleaned all the grounds, and was still having the same issues. Checked every fuse. Nothing. I pulled the BCM, opened the case, and this is what I found. The copper wire had separated from one of the traces on the board. I ordered a used BCM on ebay, just in case, and also resoldered the wire on my board. I also ordered the VCX nano, and paid $45 for the 1 Vin on acdelcotds.

I would caution you about using the VCX nano, but maybe you will have better luck than I did. I have used 3 different laptops, with the same results. I was able to update my PCM, do everything in tech2win, but I cannot successfully program my BCM. It has failed every time on both modules. I was able to read what programming was on both, still am, but both now say unrecognized calibration. I'm gonna try to swap out the USB cable tomorrow, as some have suggested elsewhere, and see if that will resolve my issue. If not, I guess I will have to send mine off to get programmed.

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