Dash Dimmer activates voice and radio on 2017 prime advanced

A suite of problems started suddenly as I was driving down the road one sunny day. The voice command started to come on by itself and asking me to say a command, repeatedly. When this started, the radio also started turning on by itself, switching the source randomly, and sometimes increasing or decreasing the volume to max or min. My wife figured out that turning the dashboard dimmer light all the way down stops these problems. As soon as the dimmer is turned up even one step, the problems resume. I tried swapping out the steering wheel control switches and the dash brightness/parking assist/vehicle control system switch, with no change in symptoms. My next guess is to swap out the wiring harness, but I haven't figured out if it's the whole upper dash instrument panel harness or a different harness. Is it likely to be the harness? Does anyone know the part number? Any other ideas? Thanks for any help!

 

Update: I tried replacing the speedometer cluster, but the problem persisted. At this point my only theory remaining is that when the dash lights are turned on, current in the wire induces signal in the wires serving the voice and radio circuits, so replacing the wire harness seems to be the best option. Any other ideas?