Here's a thought for one of y'all with it installed. Try turning on intercom and cb. Maybe it shares priority with one of them.
I obviously have been reading this thread with great interest. More so, because I have the Bluetooth Module installed currently. One of my thoughts was about the CB & Intercom as well as volume control of any of the components. Is the volume on the Garmin turned up? Is the volume, while in AUX mode, turned up?
...The few times that mine did work today. the readout on the radio came up as "phone volume" Looks like the radio is detecting this module as the bluetooth module...
For what I have read so far, y'all are installing the bare wires into the overlay harness similar to the way the Bluetooth Module needs to be installed. That came with about 6 wires with "tips" that had to be plugged into the Molex connector that attaches to the overlay harness. It was very easy for me to put the wire in the wrong hole of that plug. Not sure if this is the case or not.
I'm not surprised that the HK unit is saying "phone volume" as to do otherwise would mean that the software would have already had to be programed with this feature built in. If that was the case, the MoCO would have released this product 3 years ago when the Bluetooth Module was first introduced. In order to change that phrase, it would require a software upgrade that no one is currently aware of. Maybe it's something in the works?