help with headunit instillation
 

hello everyone, im helping a friend of mine with a 91 protege to install a headunit he has. Ive tried hooking this thing up to power and ground to test it, but it wont come on. i think the headunit he has is broken and we are about to buy a new one but first i wanted to know if anyone has a key for what color the wires are and what their function is? any help would be appreciated!

go to this website http://www.installdr.com/QuickWiring.html and click on mazda