Software issues: 

1. make sure the car type is right 

2. setting - more setting - sound volume - turn on 

3. If your car has Digital Amplifier originally, then may not output the sound through digital amplifier, because our units don't support digital amplifier. In this case, need an amplifier bypass directly connect with speakers. or install aftermarket amplifier. 

4. CANBUS software is not right, please contact us for solving the issue 

Hardware issues:

1. make sure the harness is good and works 

2. sound processing unit is broken, please contact us for solving the issues