It should be automatic. Anytime you receive or transmit, the radio should go silent. It has to do with rules about transmitting music over the CB so Hondas solution is to turn off the radio when these happen. But other issue is that static on CB will also cut off the radio sounds. You have to adjust the squelch up to control the static and also so you only receive CB transmissions that are closer. Squelch is on left handlebar controls with CB volume and CB channel switches. Also remember if you are not using a headset, make sure that CB is set to come over the dash speakers.