Buy a repair manual like Chilton's they have wiring and vacuum diagrams.
check your local library in the reference section
Find the Haynes repair manual for the vehicle at AutoZone. They have complete wiring diagrams in them.
Here is a link to some and they are free too http://www.modifiedlife.com/car-stereo-wiring-diagrams-and-car-radio-wiring-diagrams/
Your best bet is to buy a Chilton's Repair Manual. It has lots of pictures and diagrams
One source that I found for wiring diagrams is All Data - Do It Yourself. They do charge a subscription fee, but it was the only place I was able to find some wiring diagrams I needed for a 1997 Expedition. I've placed a link below.
Wiring Diagrams
In a Haynes 2001 Honda Spree repair manual, you will find wiring diagrams. The books include pictures and directions for getting the job done quickly.
WIRING DIAGRAMS TOYOTA WIRING DIAGRAMS TOYOTA
Which one, chassie or engine? There are several diagrams. I use the Clinton CD Manual.
How to write it is a website where there are many diagrams. There are hundreds of resources on the Internet to print out house wiring diagrams.
where can I find yamaha wiring diagrams
Chilton's repair manual includes several wiring diagrams.