turn off the backup camera (rear view mirror) all together. I have the same thing...thought it was my radio buzzing. It was my back up camera. I have also had issues with left turn signal having a 20 second delay before the left camera shows up. Sometimes it works as it should...others a long delay. The delay ONLY happens when the rear view camera is on. When it is off, there is no delay in the left turn camera. I am being told likely loose wire in the harness. But the buzzing definitely for me is coming from the mirror.
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