To find it:
1. Locate the underhood fuse block: This is usually a black plastic box near the battery. The lid should have a diagram showing the fuse locations and what each fuse controls.
2. Consult the fuse block diagram: Carefully examine the diagram on the inside of the fuse box lid. Look for a fuse related to the radio, audio, or accessories. The amperage rating might be listed as well. Sometimes, it's a shared circuit with other accessories.
3. Check the owner's manual: Your owner's manual should also have a fuse diagram. This is the most definitive source.
If you can't find it using the diagram: Your best bet is to take your vehicle to a qualified mechanic or auto parts store. They will have access to wiring diagrams and can help you locate the correct fuse. They can also test the fuse to make sure it's blown. Remember to always disconnect the negative battery terminal before working with fuses or electrical components.