How To Use Automotive Diagnostic Scanners

Book Preface

With the availability of code readers and scan tools targeted at the consumer market through retailers such as Sears, Walmart, auto parts stores, and online, it’s more than evident that the aftermarket automotive electronic equipment manufacturers 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 five books, both for automotive- and motorcycle-related subjects, to fill this information gap. This book is a second edition of my How to Use Automotive Diagnostic Scanners. There are expanded sections in many of the chapters, especially in chapters four and five, where I cover updated and new scan tools and code readers. I also cover smart phone apps (Bluetooth and WiFi) and laptop/PC-based scan tools.

In this book, the first generation of on-board diagnostics (OBD-I) will be discussed in chapter one and chapter two 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 three covers electronic fuel injection, oxygen sensors, and catalytic converter operation. Code readers are discussed in chapter four with scan tools following in chapter five. How an engine works, and especially how to separate engine mechanical problems from OBD-II system diagnostics, is discussed in chapter six, and chapter seven provides some practical applications for using a scan tool to diagnose emission-related problems.

If while reading this book you need a refresher on the meaning of “OBD,” “DLC,” or any other term found in the text, the Appendix contains a convenient glossary of OBD-II automotive terms.

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 e-mail if you want to comment on any of the books I have written or just to say hello.

I would like to thank the following individuals for helping me with research and information for this book. Without their assistance, I would be lost more than I usually am. Curt Moore and Craig Healy from the S.C.M. Hotline; their technical editing and suggestions saved me from writing something stupid.
Fisette Justin of the Bosch Automotive Aftermarket Division, who generously provided me with information and photographs on scan tools and code readers; and Elwood’s Auto Exchange, where I was able to take many of the photos used in the book. Darwin Holstrom, my editor at Motorbooks International, and my wife, Leslie, whose editing skills have always vastly improved what I write.
So take a break from working under the hood of your car, sit back, relax, and read all about how scan tools, code readers, and your Android or Apple smart phone work with your car or truck’s OBD-II on-board computer. Hopefully you’ll find what this book contains is entertaining, as well as informative.

Tracy Martin