1. The battery is low; But it is unlikely;

2. There is something wrong with the sound amplification circuit, which makes the sound unable to be amplified; This possibility is relatively large;

3. There is something wrong with the voice control circuit, especially the volume of the sound. There is a filter capacitor that leaks so that the sound is not loud; This possibility is the greatest;

4. There is something wrong with the speaker, resulting in low sound. In this case, it is often accompanied by hoarseness and distortion, and this possibility is also relatively large;

It's just that this may be the reason, which will lead to low sound, so we should deal with it according to the corresponding situation. The mp3 player in the car has volume adjustment, but we can't control the volume adjustment of the car itself (it seems to be a tongue twister, I don't know if I can watch it). If it is turned to the maximum, the sound is still very low, which may be the quality problem of the car mp3.