No, there's typically no dedicated fuse specifically for the speakers in a 2003 Chevy Avalanche (or most vehicles). The speaker power is drawn from the amplifier (if equipped) or directly from the radio's output, which is protected by the radio's internal circuitry and the main radio fuse.
If your speakers aren't working, the problem is more likely a blown radio fuse, a faulty radio, a wiring issue, or a problem with the speakers themselves. Check your vehicle's owner's manual for the location and amperage of the radio fuse.
