I have a 90 civic HB, I'm trying to put a aftermarket stereo in, I kno the blue and white stripe wire is constant 12v, but I don't have a yellow red stripe wire for switched? Went to junk yard to possibly get a new under dash to replace it but noticed other ones don't have it neither? Am I missing something or is it the 90-91 different from 88-91?

Help please

 

Just check the wires with a test light to see which one turns on with the ignition.