blinking side mirrors eh??? you know for a fact you have 3 wires. Most likely, one wire is going to be a ground wire, one wire is going to be a constant 12 volt wire, and the other is going to the turn on wire. Reply with this specific information:
-The guage wire for the black, blue and white.
-Is the mirror a side marker?
(will turn on when headlights are on and will blink with turn signals)
-Strip the wires, test with these cominations:
**black - : blue +**
**black - : white +**
**black - : blue + : white +**
good luck with your "blinking mirrors"