2001 Yukon XL 5.3 K1500 Instrument Cluster Panel & Message Center Inoperative, Interesting Symptom 

Well, that's why I showed exactly where it was at 2:08 in the video, as well as describing where it was and showing the labeling on the diagram earlier in the video! I even showed where the wires broke off of the eyelet immediately after showing where it's bolted on to the engine! I hope you found your problem!

Yes, the ground was exactly where I showed it on video and on the diagram. And yes, I believe the DLC pin 4 chassis ground and pin 5 sensor ground were being tied together by the scanner dongle, although I did not prove that part of my hypothesis.

It's at the right rear of the engine, meaning as if you were sitting in the car, so passenger side. If I recall correctly, it's hard to see without a mirror.

@@ClaytheBMXer thanks for the help I am going to take that out this afternoon

Copy and pasted from an earlier comment: "I showed exactly where it was at 2:08 in the video, as well as describing where it was and showing the labeling on the diagram earlier in the video! I even showed where the wires broke off of the eyelet immediately after showing where it's bolted on to the engine" I hope this helps you!

Here, also, is my comment to another person who mentioned they still had trouble finding it: "It's at the right rear of the engine, meaning as if you were sitting in the car, so passenger side. If I recall correctly, it's hard to see without a mirror."