Typically, the radio power wires in a standard automotive installation are yellow for constant 12V (memory), red for ignition/switched 12V, and black for ground. Additional wires may handle memory, illumination, and remote turn-on depending on the harness.
Color schemes are not universal: vehicle manufacturers and aftermarket harnesses may use different colors, and some OEM radios follow non-ISO conventions. Always verify with the vehicle’s wiring diagram or the radio’s installation manual before wiring.
Standard color codes for radio power wires
The following describes the common color usage found in many aftermarket installations based on ISO 10487 conventions.
- Yellow — Constant 12V supply (memory). Keeps radio memory and presets when the ignition is off.
- Red — Switched/Accessory 12V (ignition). Powers the radio when the ignition is on.
- Black — Ground. Provides the radio’s return path to the chassis.
- Orange — Illumination. Dash-light control for display brightness; not present on all systems.
- Blue — Remote turn-on for an external amplifier or power antenna (Blue/White is also common for some OEMs). Signals the accessory circuit when the radio is on.
Always verify with the vehicle wiring diagram or the radio’s installation manual to confirm exact color mapping for your harness.
Variations and cautions
Color codes can vary widely by brand, model year, and region; the ISO 10487 standard covers many aftermarket harnesses but is not universal.
Regional differences in color schemes
Some vehicles and manufacturers may swap constant and switched wires or use non-ISO colors. For example, a few OEM setups may assign memory or constant power to red instead of yellow, or omit an illumination lead altogether.
- Some OEM or non-ISO harnesses swap constant and switched power wires. Always test with a multimeter or refer to the official wiring diagram before connecting power.
- Illumination and remote-turn-on leads may use different colors (e.g., orange for dash illumination, blue/blue-white for remote turn-on). If in doubt, rely on the harness’ color-key and the vehicle manual.
- Several vehicles may not provide a separate memory wire; memory may be handled through the radio’s own circuitry or a different feed. Check the vehicle’s service manual for specifics.
When in doubt, consider professional installation to avoid incorrect wiring, which can drain the battery or damage components. Always disconnect the battery before wiring and re-check with a test light or meter after connections.
Summary
In most common auto-radio installations, the power wires are Yellow for constant memory, Red for ignition/switched power, and Black for ground. Optional leads include Orange for illumination and Blue (or Blue/White) for remote turn-on. Because color schemes vary by vehicle and harness, always confirm with the vehicle’s manual and the radio’s wiring diagram before wiring.