Preface
When Motorbooks asked me to write this book I did not perceive an immediate need for what I thought would simply be another book on automotive scanners. After all, on-board diagnostics, second generation (OBD-II) has been around since 1996 on every car and light truck sold in the United States.
I did some investigation on what books were available on the subject by starting with several of my 22-year-old son's friends who work on their cars as a hobby. I asked them if I could take a look at the books I assumed they had acquired on scan tools and code readers. I received blank stares in response to the question, but one of them said he owned a code reader. He told me that they used the code reader mostly to turn off the check-engine light when they inadvertently caused it to come on by disconnecting an engine management computer sensor and forgetting to plug it back in when they next drove their cars. I told the group that even a code reader could do more than turn out the check-engine light, and asked them about OBD-II inspection and maintenance monitors and some other basic OBD-II related questions-again, blank stares. They told me that the code reader came with a 10-page manual, but they did not have any other information.
After a trip to the local book store I found nothing on scan tools, code readers, or OBD-II systems, so I tried the Internet-many would agree that if "It" is not on the Internet, "It" probably doesn't exist. Surfing around on my laptop, I did find several books on the subject of OBD-II, but almost all were written for professional technicians, and the few that were not only seemed to cover automotive diagnostics in general and hadnothing on scanners and code readers. However, I did find the reason that this book should be written-there are no books that cover the subject of scan tools and code readers for the do-it-yourself technician.
With the availability of code readers and scan tools targeted at the consumer market through retailers such as Sears, Wal-Mart, and auto parts stores, it's more than evident that the aftermarket automotive electronic equipment manufactures have realized a need for owners and enthusiasts to have access to what once was solely the domain of dealership and professional technicians-an automobile's on-board diagnostic system. What seemed to be missing was a source of information that tied everything together. I wrote this book about scan tools and code readers in the same easy-to-read style as my first two books on automotive and motorcycle electrical systems to fill this information gap.
In this book, the first generation of on-board diagnostics (OBD-I) will be discussed in Chapter 1. Chapter 2 will cover OBD-II, the diagnostic monitoring system in all vehicles sold in the United States since 1996, and the system that code readers and scan tools interface with. Also included is a brief history of automobile air pollution and how this problem has driven the automotive industry to produce these systems in the first place. Chapter 3 covers electronic fuel injection, oxygen sensors, and catalytic converter operation. Code readers are discussed in Chapter 4 with scan tools following in Chapter 5. How an engine works, and especially how to separate engine mechanical problems from OBD-II system diagnostics, is discussed in Chapter 6, and Chapter 7 provides some practical applications for using a scan tool to diagnose emission related problems.
This book will provide the reader with a sound understanding of how on-board diagnostics relate to engine performance and emission problems, however, because both OBD-I and OBD-II systems, on-board computers-and their numerous sensors and components-are electrical in nature, a basic understanding of automotive electricity will go a long way toward diagnosing and repairing problems with the vehicles that use these systems. My book How to Diagnose and Repair Automotive Electrical Systems, also published by Motorbooks, is the perfect companion book to this one. I've also written on the same subject for motorcycles, Motorcycle Electrical Systems Troubleshooting and Repair, also published by Motorbooks. You can find more information about these books and some background on myself on my website at: www.tracyAmartin.com. Send me an email me if you want to comment on any of the books I have written or just to say hello.
