I bought a cheap $40 radio for my truck since the factory radio was on it's last leg. No iPhone control. Just a auxiliary and USB port.
For whatever reason, whenever I use the 3.5mm to 3.5mm adapter, I always get some sort of static/ clicky interference in the speakers. I imagine it's my phone emitting some sort of signal. I've used different cables with the same results. Makes listening to it pointless most of the time so honestly I've given up for now. FWIW, it works fine in say a 2016 model vehicle with an auxiliary port built into the factory system.
What could be causing this? I am not too "car audio" savvy. I have a nice Kenwood in my Jeep that was a (at it's time: 2010) flagship model with iPhone controls. No issues whatsoever even with my newer iPhone 6S.
Unplug the phone from the charger, that should get rid of the ground loop.
If not that cheap radio may have a faulty aux jack. I have repaired a few with broken solder joints to tye pc board. Have you trsted it with a walkman or other? And wiggled the connection.
If not it might be phone radio interference getting into the audio front end and overloading it. In that case you might get a ferrite ring core from radioshack and coil you cable through it few times to kill the high frequency fuzz.
Most audio inputs have input. Filter capacitors on them for this. At $40 pricepoint they might not bother.
Re: Speaker interference with iPhone/ aux. cable
#4593780 12/04/1710:20 AM12/04/1710:20 AM