Chapter 12 Basic Diagnostic Procedures . . . . . . . . 225 Strategy-Based Diagnostics . . . . . . . . . . . . . . . 226 Seven Diagnostic Steps. . . . . . . . . . . . . . . . . . 226 Step 1: Determine the Exact Nature of the Complaint | Step 2: Check for Obvious Causes | Step 3: Determine Which Component or System Is the Most Probable Cause of the Problem | Step 4: Perform Pinpoint Tests | Step 5: Check for Related Problems | Step 6: Correct the Defect | Step 7: Recheck System Operation and Follow Up | Importance of Follow-Up Using Strategy-Based Diagnostics to Diagnose Specifi c Problems . . . . . . . . . . . . 228 Example 1—Aft ermarket Radio | Example 2— MIL Comeback | Example 3—Hesitation | Example 4—Vibration | Example 5—Stalling | Example 6—Rough Idle | Example 7—Multiple Problems | Example 8—Intermittent MIL Light | Example 9—Intermittent Engine Cutout | Example 10—Poor Fuel Economy | Example 11—Hard Starting Diesel Engine | Example 12—Failed Emissions Test Chapter 13 Troubleshooting Techniques . . . . . . . . . 241 Basic Diagnostic Procedures . . . . . . . . . . . . . . 242 Learning to Diagnose | Evaluating Customer Input | Filling Out Work Orders | Obtaining Vehicle Identifi cation Numbers | Road Testing | Performing Visual Inspections | Principles of Diagnosis | Using Service Information | Diagnosing Electrical Problems | Diagnosing Charging and Starting Systems | Diagnosing Engine Problems | Diagnosing Computer Control Systems | Diagnosing Drive Train Problems | Diagnosing Other Vehicle Systems Deciding on Needed Work . . . . . . . . . . . . . . . . 256 Always Perform Additional Tests | Deciding on the Proper Repair Steps | Contacting the Owner about Needed Work Follow-Up After Repairs . . . . . . . . . . . . . . . . . . 258 Chapter 14 Electrical System Diagnosis and Repair . . . . . . . . . . . . . . 261 Identifying Driveability Problems Caused by the Electrical System . . . . . . . . . . . 262 Preparing to Diagnose Electrical Problems. . . . 262 Using Schematics to Diagnose Electrical Problems | Visual Inspection Test Equipment Used to Diagnose Electrical Problems . . . . . . . . . . . . . 268 Using Jumper Wires | Using Test Lights | Using an Ammeter | Using a Voltmeter | Using an Ohmmeter | Scope Checking Specifi c Components . . . . . . . . . . . . 271 Testing Relays | Testing Ignition Coils | Testing Solenoids | Testing Servo Motors | Testing Solid-State Components Electrical Repair Operations . . . . . . . . . . . . . . 274 Repairing Damaged Wiring | Replacing Fusible Links | Disassembling Connectors | Repairing Connectors Checking Starting and Charging Systems. . . . . 276 Battery | Starting System | Alternator Follow-Up for Electrical Repairs . . . . . . . . . . . . 282 Chapter 15 Computer Control System Diagnosis and Repair. . . . . . . . . . . . . . . . . . . . . . . 287 Beginning Computer Control Diagnosis . . . . . . 288 Retrieving ECM Trouble Codes . . . . . . . . . . . . . 289 Code Retrieval Process | Diagnostic Trouble Code Format | Interpreting Trouble Codes | Comparing Hard and Intermittent Codes | Separating Hard and Intermittent Codes | When Th ere Are No Trouble Codes Interpreting Scan Tool Data . . . . . . . . . . . . . . . 293 PIDs, TIDs, MIDs, and CIDs Using the Misfi re Monitor. . . . . . . . . . . . . . . . . 294 Computer Sensor and System Testing . . . . . . . 294 Testing Oxygen Sensor Operation | Testing Mass Airfl ow (MAF) Sensors | Testing Manifold Absolute Pressure (MAP) Sensors | Testing Temperature Sensors | Testing Th rottle Position Sensors | Testing Crankshaft and Camshaft Position Sensors | Testing Knock Sensors | Testing Vehicle Speed Sensors | Testing Output Devices with a Scan Tool | Using a 9-Volt Battery to Test Parts Contents 9