The shield is not a ground . The shield wire runs from the camera to the radio normally . The shield is there ONLY to reduce electronic interference from other electrical items like the electronics of the engine , the air conditioner , the alternator ect ect... Essentially the shield wire reduces static in the video feed .
The shield is a non issue , your video feed is already protected by a shield wire from the factory video feed to the mirror and now with the infotainment harness to the radio your shielded .
Your issue is your trucks BCM is configured improperly to allow the radio to accept and display the complete video signal your currently receiving from the infotainment harness . You will not receive the video of the bu cam untill the BCM is configured to do so .
You can reinstall your video capable mirror and receive the bu cam video there , and when you get the BCM configured properly you will have back up cam video on both the 5" RA2 radio screen and the mirror , which is pretty cool [emoji1303]
At that point you could just remove the mirror and reinstall the mirror with microphones or not .
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