Ensure the ground (black wire) is attached to clean, unpainted metal. If the issue persists, install an inline 3.5mm ground loop noise isolator. The device disconnects frequently.
Use plastic panel tools to gently pry away the trim surrounding your car stereo. Unbolt the radio securing screws.
Mount the small circuit board using double-sided foam tape. Ensure it is not tightly enclosed by heavy metal brackets, which can severely degrade your Bluetooth signal range. Pairing and Operation Instructions