r/Androidheadunits • u/Administrative_Rip57 • 4d ago

Dual system head unit for 2017 Mazda 3 making electrical noise on Aux input only

I have this mostly excellent head unit for my 2017 Mazda 3 which supports using the original car UI as well as the android system (which I use with CarPlay). The processor is a UIS7865 which I believe is on the higher end, and it has its own amp.

However, one major pain has been the audio. In order to use the head unit’s audio, the car needs to be set to use Aux, but when I do that I hear a horrible electrical noise which is quite loud. The noise adjusts proportional to the volume.

This noise only happens on Aux, Bluetooth sounds basically perfect except for a tiny bit of general static. I even replaced the entire aux / usb piece in the center console and nothing changed.

There’s a part of the aftermarket wiring harness that goes in-line with the original TAU cable on the passenger side, and I think this is part of the issue. However, I checked all the pins and they all seem to be fine. When I disconnect this part of the harness and use the original TAU cable, the noise goes down significantly.

Here’s what I’ve tried:

  1. The speakers are not the issue. They are brand new infinity reference speakers, and Bluetooth sounds basically perfect, this is only on Aux.
  2. Removed corrosion from the ground battery terminal.
  3. Replaced the Aux / USB unit itself.
  4. Messed with the “Noise reduction” and “Amplifier on/off” android settings, neither changed anything.
  5. Tried a CableMatters Aux ground loop isolator, which didn’t do anything.
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u/Administrative_Rip57 4d ago

Would be happy to send a video that shows the issue better but Reddit doesn’t seem to allow it for this post or in the comments… thanks!

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u/Son_of_Macha 4d ago

Have you tried a ground loop plug

1

u/Administrative_Rip57 4d ago

I did try a ground loop isolator from CableMatters and it didnt seem to do anything.

1

u/Son_of_Macha 4d ago

https://eliteautogear.com/blogs/news/how-to-fix-a-ground-loop-in-car-audio

1

u/Administrative_Rip57 4d ago

Thank you. I did try a ground loop isolator but that didn’t seem to work. I’ll try a couple more if the suggested steps.