can anyone help me im after a complete set of wiring diagrams for a 2wd saff cos please! i dont mind if i have to buy them!

a friend on mine has fitted a head unit into one and now the central locking downt work! he dont think that he has doen anythine worng, and he is no muppet when it comes to car wiring! but he cant find the fault! i havent seen this car yet but i guess i would end up doing the same as he has!

anyone help or tell me where i can buy a i diagram

thanks for looking