The blue wire in an amp wiring kit is usually the amplifier remote turn-on wire. Its job is to tell the amplifier when to switch on and off with the vehicle’s audio system.
In most aftermarket installations, the blue remote wire carries a low-current 12-volt signal from the head unit to the amplifier. When the stereo turns on, this signal activates the amplifier. When the stereo turns off, the signal stops and the amplifier powers down.
This wire is important because an amplifier should not stay powered on all the time. If the remote turn-on wire is connected incorrectly, the amplifier may not turn on, may stay on constantly, or may drain the vehicle battery.
In vehicles with factory head units, the installation can be more complex because there may not be a dedicated remote turn-on output. In these cases, installers may use a suitable switched 12-volt source, line output converter, integration module or DSP interface, depending on the vehicle and system design.
Because modern vehicles can have sensitive electronics, factory amplifiers and integrated infotainment systems, amplifier wiring should be done carefully. For the safest and cleanest result, speak with your nearest Focal Authorised Australian Dealer. A professional dealer can connect the remote turn-on wire correctly and ensure your Focal amplifier, speakers or subwoofer system operates reliably.
