What fuse does a car stereo use?
A car stereo has two fuses: an ATC blade fuse in the vehicle fuse box (for the radio circuit, typically 10–15 A), and an in-line AGC glass tube fuse on the power wire behind the head unit (typically 10–25 A).
Fuse 1: The vehicle fuse box
The vehicle's fuse box contains an ATC blade fuse for the radio or accessory power circuit. This is usually labeled “RADIO”, “ACC”, or “AUDIO” on the fuse box diagram. Common ratings are 10 A (red) or 15 A (blue).
If the radio has no power at all, start here. Pull the labeled fuse and inspect it against the light for a broken element.
Fuse 2: The in-line power wire fuse
Aftermarket head units and factory radios draw power through a wiring harness. The main constant-power yellow wire almost always has an in-line fuseholder close to the battery end of the wire (within 18″ of the battery or fuse box). This fuseholder typically takes a 1/4″ × 1-1/4″ AGC glass tube fuse.
The rating depends on the head unit's power draw. Check the stereo's installation manual for the recommended value — 10–25 A is the typical range for a head unit without external amplifiers.
For amplifiers: MAXI or ANL fuses
If you have an external amplifier, the amplifier's power cable must be individually fused close to the battery. Depending on the amplifier's total RMS output:
- Under 100 W RMS: 20–30 A MAXI blade or AGC in a standard in-line holder
- 100–500 W RMS: MAXI blade (30–80 A) or ANL bolt-down fuse
- Over 500 W RMS: ANL or MIDI fuse block
Key rule
Always replace in-line fuses with the exact same type and amperage. If a fuse keeps blowing, there is a wiring or equipment fault — do not upsize the fuse.