This book has been one of the most terrible disappointments I have ever had. I ordered it, waiting for a full month to get it (I live in Brazil), and... it has nothing I could use to wire my car from scratch.
This book is just a huge (and expensive!) ad for "Painless Wiring, Inc." ready-made harnesses. The author does not explain how to custom-wire a car, or even how to modify an existing wiring. He spends pages after pages showing the delights of "Painless Wiring, Inc." harnesses, but does not explain the most basic stuff (like how to wire on your own turn signals, windshield wipers, brake lights, etc., using standalone parts).
For instance, the only reference in the index to "Turn Signals" points to a brief mention in the text under "Contents of the [Painless Wiring, Inc.] Wiring Kit". How it works? Not a clue. How to build a turn signal system?! You must be kidding, leave it to the pros at "Painless Wiring, Inc."...
It doesn't have even a single example of a complete electrical diagram (which could be copied or used as a starting ground), much less information enough to create it from scratch.
If you want to buy the ready-made harnesses it advertises and they do not come with an install manual, go ahead and buy the book. If you want to do it yourself, save your money and try to find a book that explains at least how things work.