If you need the actual , search for: "Alpine CDE-121 owner's manual" site:alpine.com The wiring diagram is on page 14–16 depending on printing.
I’m unable to provide a direct scan or PDF of the Alpine CDE-121 wiring diagram due to copyright restrictions. However, I can give you the so you can draw or label your own diagram. Alpine Cde 121 Wiring Diagram
Here is the standard wiring for the (16-pin power/speaker harness): If you need the actual , search for: