It is the amplifier enable - turn on wire. Basically if the radio comes on power (voltage) goes on this wire to tell the amplifier to come on. And the amp is under the driver's seat.
The radio colors in a 1995 Ford Escort include blue and red, blue and black, and red and black. Wires can also be violet, blue and orange, blue and white, red and blue, and white and green.
There are twelve different wires for the stereo system in a 1995 BMW 318i. The car radio constant 12V+ wire is red/white, the radio switched 12v+ wire is purple/white, the radio ground wire is brown, and the radio antenna trigger is white. For the front speakers, the left front speaker wire (+) is yellow/red, the left front speaker wire (-) is brown/orange, the right front speaker wire (+) is black/red, and the right front speaker wire (-) is brown/orange. For the rear speakers, the left rear speaker wire (+) is yellow/black, the left rear speaker wire (-) is black/orange, the right rear speaker wire (+) is blue/black, and the right rear speaker wire (-) is brown/orange.
In a 1991 Lincoln Town Car, the radio battery constant 12v+ wire is green/yellow, the radio accessory switched 12v+ is yellow/black, the ground wire is red, the illumination wire is blue/brown, and the antenna trigger wire is orange/blue. For the front speakers, the left front speaker wire (+) is orange/green, the left front speaker wire (-) is black/white, the right front speaker wire (+) is white/green, and the left front speaker wire (-) is black/white. For the rear speakers, the left rear speaker wire (+) is pink/green, the left rear speaker wire (-) is blue/orange, the right rear speaker wire (+) is pink/blue, and the right rear speaker wire (-) is green/orange.
Radio Constant 12V+ Wire: Light Green/Purple Radio Switched 12V+ Wire: Yellow/Black Radio Ground Wire: Black Radio Illumination Wire: Red/Black Radio Dimmer Wire: N/A Radio Antenna Trigger Wire: N/A Radio Amp Trigger Wire: N/A Front Speakers Size: N/A Front Speakers Location: N/A Left Front Speaker Wire (+): Orange/Light Green Left Front Speaker Wire (-): Light Blue/White Right Front Speaker Wire (+): White/Light Green Right Front Speaker Wire (-): Green/Orange Rear Speakers Size: N/A Rear Speakers Location: N/A Left Rear Speaker Wire (+): Tan/Yellow Left Rear Speaker Wire (-): Gray/Light Blue Right Rear Speaker Wire (+): Orange/Red Right Rear Speaker Wire (-): Brown/Pink
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Run the yello wire of your new radio to a constant power wire (usually orange). A good one is the orange wire running to your cigarette lighter.
Illumination wire. Connect it to your dash lights' 12v+ so that when you turn your lights on at night, the lights on the head unit dim so they aren't blindingly bright.
Orange
The radio wiring colors for a 2003 Ford F-150 XLT are simple to follow and identify. The car radio battery constant 12V+ wire is light green/pink, the car radio accessory switched 12V+ wire is black/violet, the car radio ground wire is black/green, the car radio illumination wire is light blue/red, and the car stereo antenna trigger is blue. For the front speakers, the left front speaker wire (+) is gray/light blue, the left front speaker wire (-) is tan/yellow, the right front speaker wire (+) is white/light green, and the right front speaker wire (-) is dark green/orange. For the rear speakers, the left rear speaker wire (+) is orange/light green, the left rear speaker wire (-) is light blue/white, the right rear speaker wire (+) is orange/red, and the right rear speaker wire (-) is brown/pink.
There is a color code for the speaker wires in a 1995 Mercury Mystique. The radio battery constant 12v+ wire is orange/black, the radio accessory switched 12v+ wire is blue/black, the radio ground wire is black/green, and the illumination wire is white/green. The left front speaker wire (+) is white/black, the left front speaker wire (-) is brown/yellow, the right front speaker wire (+) is white/red, and the right front speaker wire (-) is brown/red. The left rear speaker wire (+) is white/violet, the left rear speaker wire (-) is brown/white, the right rear speaker wire (+) is white/violet, and the right rear speaker wire (-) is brown/white.
In a Ford Fiesta, the radio constant 12v+ wire is yellow/red, the ground wire is black/blue, and the illumination wire is blue. For the front speakers, the left front speaker wire (+) is white, the left front speaker wire (-) is white/brown, the right front speaker wire (+) is white/violet, and the right front speaker wire (-) is white/orange. For the rear speakers, the left rear speaker wire (+) is white/green, the left rear speaker wire (-) is brown/yellow, the right rear speaker wire (+) is brown/white, and the right rear speaker wire (-) is brown/blue.
In a 1995 Ford F-250, the radio battery constant 12v+ wire is green/yellow, the radio accessory switched 12v+ wire is yellow/black, the ground wire is red or black, and the illumination wire is blue/red. For the front speakers, the left front speaker wire (+) is orange/green, the left front speaker wire (-) is black/white, the right front speaker wire (+) is white/green, and the right front speaker wire (-) is black/white. For the rear speakers, the left rear speaker wire (+) is pink/green, the left rear speaker wire (-) is pink/blue, the right rear speaker wire (+) is pink/blue, and the right rear speaker wire (-) is green/orange.