Things You'll Need
Instructions
Replace the batteries in the Wiimote (Nintendo Wii controller) you are using with your "Rock Band" guitar. Low batteries can cause Wiimotes to de-sync from the console or shut off during play.
Ensure that your "Rock Band" wireless dongle (the device that sends signals to your guitar) is correctly hooked up. It should be connected to an empty USB port on your Nintendo Wii and will show a glowing blue light when on.
Re-sync your guitar. To do this, disconnect all extra controllers from the Wii, then hold down the "Sync" buttons on both the USB dongle and guitar. The dongle's button has a guitar icon, and the "Sync" button on the guitar can be found just under the whammy bar.
Replace the Wiimote in your guitar with a different Nintendo Wii controller. If the guitar works with a different Wiimote, chances are good the other controller is causing the problem.