The electronic control unit and other electronic controls are connected to every major system of a car built within the past 15 years, yet when there is a problem or an error code, many enthusiasts do not know how to go about fixing the problem. With this book, an affordable hand held scanner, and other common tools, the average enthusiast can diagnose and fix most common problems, rather than bringing the vehicle to a dealership for repair at shop rates of $100 per hour or more.
Keith McCord recounts the history of automotive onboard diagnostic systems and creation of the rudimentary OBD I systems and the development as well as the evolution of OBD II. Currently, OBD-II (OnBoard Diagnostic II) is the standard of the industry, and this book provides a thorough explanation of this system. It details its main features, capabilities, and characteristics. It shows how to access the port connector on the car, the serial data protocols, and what the serial data means. To understand the diagnostic codes, the numbering system is defined and the table of common DTCs is shown. But most importantly, McCord provides a thorough process for trouble shooting problems, tracing a problem to its root, explaining why DTCs may not lead to the source of the underlying problem, and ultimately resolving the problem.
Almost anyone can hook a scanning tool up to the serial port and read the error, but the key to fixing the problems is using an effective trouble shooting process that resolves all the issues that may be contributing or creating the problem. McCord provides sound procedures, insight, and information for resolving most ECU and computer control problems at home with affordable consumer-grade scanners.
Introduction
Chapter 1: Introduction to On-Board Diagnostics
Closed-Loop Feedback Systems
Pre-OBD Emissions Requirements
Automotive On-Board Diagnostics
Proprietary OBD: 1980–1987
OBD-I
OBD-I.5
OBD-II
Has OBD Made a Difference?
Chapter 2: OBD-II Standardization
The Power of the Microchip
Evolution of Automotive Networks
Standardized ALDL Connector
Standardized Scan Tool Data
Diagnostic Trouble Codes
The MIL
Frame-to-Frame Data
Real-Time Data
What Information Does OBD-II Provide?
SAE Standards versus ISO Standards
Chapter 3: The OBD-II Data Interface
Data Link Connector
Determining if the Vehicle is OBD-II
OBD-II Data Protocols
Serial Communications Protocols
Troubleshooting Common DLC Connection Problems
Chapter 4: Scan Tool Interfaces
Generic OBD-II Scan Tool
Manufacturer-Specific OBD-II Scan Tool
Reading Scan Data
OBD-II Trouble Code Reader
Entry-Level OBD-II Scan Tool
Professional-Level OBD-II Scan Tool
Personality Keys and Adapters
Manufacturer-Specific OBD-II Scan Tool
Personal-Computer-Based OBD-II Scan Tool
Chapter 5: OBD-II Modes
Mode $01 – Request Data by Specific PID
Mode $02 – Request Freeze-Frame Data by Specific PID
Mode $03 – Request Set Diagnostic Trouble Codes
Mode $04 – Clear Stored Diagnostic Trouble Codes and Reset MIL
Mode $05 – Oxygen Sensor Test Results
Mode $06 – Advanced Diagnostic Mode
Mode $07 – Request On-Board Monitor Test Results
Mode $08 – Control Operations of On-Board Systems
Mode $09 – Vehicle Information
Chapter 6: Diagnostic Trouble Codes
OBD-II Drive Cycle
Anatomy of a Diagnostic Trouble Code
Pending Diagnostic Trouble Codes
Diagnostic Trouble Code Types
Current and Historical Diagnostic Trouble Codes
Plan Your Work and Work Your Plan
Chapter 7: Freeze-Frame Data
Freeze-Frame Data Reports
Freeze-Frame Data Summary
Historical Freeze-Frame Data
Breaking Down Freeze-Frame Data
Using the Freeze-Frame Data Example
Chapter 8: Emissions Tests and System Monitors
Emissions Tests
System Monitors
Misfire Monitor
Evaporative System Monitor
Heated Catalyst Monitor and Catalyst Efficiency Monitor
Secondary Air System Monitor
Fuel System Monitor
Oxygen Sensor Monitor and Heated Oxygen Sensor Monitor
EGR System Monitor
Comprehensive Component Monitor
Chapter 9: Four-Stroke Engine Cycle
Intake Cycle
Compression Cycle
Combustion Cycle
Exhaust Cycle
Otto Cycle Pressure versus Volume
Chapter 10: OBD-II and the Otto Engine Model
Pressure and Vacuum
Supercharging/Turbocharging versus Normally Aspirated
Crank, Camshaft and Valves
Static versus Dynamic Compression Ratios
Chapter 11: Controlling Fuel Systems
Closed-Loop is the Key
Fuel Combustion and Thermal Efficiency
Volumetric Efficiency
Airflow Volume
What Can Go Wrong?
Evolution of the ECM
Chapter 12: Dynamic Fuel Correction
Fuel Requirements
In a Perfect World
Fuel-Trim Adjustments
Real-Time Fuel-Trim Adjustments
Historical Fuel-Trim Adjustments
DTCs Related to Fuel Trims
P0171 and P0174 DTC Fuel-Trim System Lean
P0172 and P0175 DTC Fuel-Trim System Rich
Chapter 13: Engine Ignition Controls
What is Ignition Timing?
Generating High Voltage
Distributors
Knowing When to Fire
Controlling the Timing
Sensors that Affect Timing
Detonation and Pre-Ignition
The ECM and Detonation
What Causes Detonation and Pre-Ignition?
Chapter 14: Misfires
Misfire Types
OBD-II Misfire Detection
P030x Misfire DTC
Diagnosing a Misfire
Frame-to-Frame Data
Blinking MIL
False Misfire Code
Chapter 15: Sensors
Intake Air Temperature Sensor (IAT)
Engine Coolant Temperature Sensor (ECT)
Throttle Position Sensor (TPS)
Camshaft Position Sensor (CMP)
Crankshaft Position Sensor (CKP)
Manifold Absolute Pressure (MAP) Sensor
Mass Air Flow (MAF) Sensor
Chapter 16: Oxygen Sensors
Oxygen Sensors Are Consumable
How an Oxygen Sensor Works
Diagnosing an Oxygen Sensor
Oxygen Sensor Codes
What Causes Oxygen Sensor Failure?
Replacing an Oxygen Sensor
Glossary
Appendix A: Using a Volt Ohm Meter
Appendix B: Generic OBD-II DTC Codes
Appendix C: Manufacturer-Specific OBD-II DTC Codes
The electronic control unit and other electronic controls are connected to every major system of a car built within the past 15 years, yet when there is a problem or an error code, many enthusiasts do not know how to go about fixing the problem. With this book, an affordable hand held scanner, and other common tools, the average enthusiast can diagnose and fix most common problems, rather than bringing the vehicle to a dealership for repair at shop rates of $100 per hour or more.
Keith McCord recounts the history of automotive onboard diagnostic systems and creation of the rudimentary OBD I systems and the development as well as the evolution of OBD II. Currently, OBD-II (OnBoard Diagnostic II) is the standard of the industry, and this book provides a thorough explanation of this system. It details its main features, capabilities, and characteristics. It shows how to access the port connector on the car, the serial data protocols, and what the serial data means. To understand the diagnostic codes, the numbering system is defined and the table of common DTCs is shown. But most importantly, McCord provides a thorough process for trouble shooting problems, tracing a problem to its root, explaining why DTCs may not lead to the source of the underlying problem, and ultimately resolving the problem.
Almost anyone can hook a scanning tool up to the serial port and read the error, but the key to fixing the problems is using an effective trouble shooting process that resolves all the issues that may be contributing or creating the problem. McCord provides sound procedures, insight, and information for resolving most ECU and computer control problems at home with affordable consumer-grade scanners.
Introduction
Chapter 1: Introduction to On-Board Diagnostics
Closed-Loop Feedback Systems
Pre-OBD Emissions Requirements
Automotive On-Board Diagnostics
Proprietary OBD: 1980–1987
OBD-I
OBD-I.5
OBD-II
Has OBD Made a Difference?
Chapter 2: OBD-II Standardization
The Power of the Microchip
Evolution of Automotive Networks
Standardized ALDL Connector
Standardized Scan Tool Data
Diagnostic Trouble Codes
The MIL
Frame-to-Frame Data
Real-Time Data
What Information Does OBD-II Provide?
SAE Standards versus ISO Standards
Chapter 3: The OBD-II Data Interface
Data Link Connector
Determining if the Vehicle is OBD-II
OBD-II Data Protocols
Serial Communications Protocols
Troubleshooting Common DLC Connection Problems
Chapter 4: Scan Tool Interfaces
Generic OBD-II Scan Tool
Manufacturer-Specific OBD-II Scan Tool
Reading Scan Data
OBD-II Trouble Code Reader
Entry-Level OBD-II Scan Tool
Professional-Level OBD-II Scan Tool
Personality Keys and Adapters
Manufacturer-Specific OBD-II Scan Tool
Personal-Computer-Based OBD-II Scan Tool
Chapter 5: OBD-II Modes
Mode $01 – Request Data by Specific PID
Mode $02 – Request Freeze-Frame Data by Specific PID
Mode $03 – Request Set Diagnostic Trouble Codes
Mode $04 – Clear Stored Diagnostic Trouble Codes and Reset MIL
Mode $05 – Oxygen Sensor Test Results
Mode $06 – Advanced Diagnostic Mode
Mode $07 – Request On-Board Monitor Test Results
Mode $08 – Control Operations of On-Board Systems
Mode $09 – Vehicle Information
Chapter 6: Diagnostic Trouble Codes
OBD-II Drive Cycle
Anatomy of a Diagnostic Trouble Code
Pending Diagnostic Trouble Codes
Diagnostic Trouble Code Types
Current and Historical Diagnostic Trouble Codes
Plan Your Work and Work Your Plan
Chapter 7: Freeze-Frame Data
Freeze-Frame Data Reports
Freeze-Frame Data Summary
Historical Freeze-Frame Data
Breaking Down Freeze-Frame Data
Using the Freeze-Frame Data Example
Chapter 8: Emissions Tests and System Monitors
Emissions Tests
System Monitors
Misfire Monitor
Evaporative System Monitor
Heated Catalyst Monitor and Catalyst Efficiency Monitor
Secondary Air System Monitor
Fuel System Monitor
Oxygen Sensor Monitor and Heated Oxygen Sensor Monitor
EGR System Monitor
Comprehensive Component Monitor
Chapter 9: Four-Stroke Engine Cycle
Intake Cycle
Compression Cycle
Combustion Cycle
Exhaust Cycle
Otto Cycle Pressure versus Volume
Chapter 10: OBD-II and the Otto Engine Model
Pressure and Vacuum
Supercharging/Turbocharging versus Normally Aspirated
Crank, Camshaft and Valves
Static versus Dynamic Compression Ratios
Chapter 11: Controlling Fuel Systems
Closed-Loop is the Key
Fuel Combustion and Thermal Efficiency
Volumetric Efficiency
Airflow Volume
What Can Go Wrong?
Evolution of the ECM
Chapter 12: Dynamic Fuel Correction
Fuel Requirements
In a Perfect World
Fuel-Trim Adjustments
Real-Time Fuel-Trim Adjustments
Historical Fuel-Trim Adjustments
DTCs Related to Fuel Trims
P0171 and P0174 DTC Fuel-Trim System Lean
P0172 and P0175 DTC Fuel-Trim System Rich
Chapter 13: Engine Ignition Controls
What is Ignition Timing?
Generating High Voltage
Distributors
Knowing When to Fire
Controlling the Timing
Sensors that Affect Timing
Detonation and Pre-Ignition
The ECM and Detonation
What Causes Detonation and Pre-Ignition?
Chapter 14: Misfires
Misfire Types
OBD-II Misfire Detection
P030x Misfire DTC
Diagnosing a Misfire
Frame-to-Frame Data
Blinking MIL
False Misfire Code
Chapter 15: Sensors
Intake Air Temperature Sensor (IAT)
Engine Coolant Temperature Sensor (ECT)
Throttle Position Sensor (TPS)
Camshaft Position Sensor (CMP)
Crankshaft Position Sensor (CKP)
Manifold Absolute Pressure (MAP) Sensor
Mass Air Flow (MAF) Sensor
Chapter 16: Oxygen Sensors
Oxygen Sensors Are Consumable
How an Oxygen Sensor Works
Diagnosing an Oxygen Sensor
Oxygen Sensor Codes
What Causes Oxygen Sensor Failure?
Replacing an Oxygen Sensor
Glossary
Appendix A: Using a Volt Ohm Meter
Appendix B: Generic OBD-II DTC Codes
Appendix C: Manufacturer-Specific OBD-II DTC Codes