Navigation Mute, CarPlay Head Unit

Hi Forum, I am looking at installing a CarPlay head unit. Some of the models I looked at have a interrupt/mute navigation input, which as I understand lowers the volume of mutes music playing. few questions around this feature: When using Carplay and navigation I assume music playing will be muted by the operating system (correct?) I was considering using reverse to the mute input. So when reverse is selected the music mutes and the audible reverse sensor is easier to hear. (is the input 12VDC + or -?) any thoughts?

I believe the mute wire is a negative input. Check the manual for the make/model unit you are considering. It may not be a functional wire anymore, as Bluetooth is already built into most units themselves. It could be that it just uses the same wiring harness as older models. If it turns out this is negative, you can use a relay to change the polarity of the reverse wire: https://www.the12volt.com/relays/relaydiagram9.html If this wire doesn't do anything, you can always interrupt the accessory wire of the unit with a relay. Cut the accessory wire of the unit and connect one side to 87a. Connect the other side to 30. Connect 85 to ground and 86 to your reverse wire. (similar to this): https://www.the12volt.com/relays/relaydiagram10.html Now, whenever you go into reverse, the unit will power off and you can hear the audible warning.My ex once told me I have a perfect face for radio.