Wiring problem 1985 Mirage

Hi, my mate has a 1985 mitsubishi mirage and his new headunit is just not working. The information from this site has: Constant 12V+     RED / Black Switched 12V+      Blue Ground              Chassis However, I'm not sure what RED / black means, I assume thats its red with black stripe but all I have from to work with is a red wire, a black wire and a blue wire. Using blue as switched and either black or red as constant doesn't work. Do I need to tie red and black together as constant? nb. ground is at ground the whole time Appreciate any help/ideas!!!!!!

What you need to do is test the wires with a multimeter.  Ground the black wire as you have it, then test the wires for constant, and switched.  Set your meter to dc voltage, place the negative lead to ground, and the positive lead to your suspect wire.  Constant will obviously show 12 volts at all times.  Switched will show 12 volts when the key is turned forward.My ex once told me I have a perfect face for radio.

Cheers for the reply geepherder, I don't know why i didn't think of that!