Table of Contents 652 Body Electrical Diagnosis Electrical Diagnostic Section 3: Topics ................................................................................................. 133 Introduction ......................................................................................... 134 Visual Inspection ................................................................................ 134 Tools Operate the Circuit Thoroughly ...................................................... 134 Checking Connectors & Terminals ................................................. 135 Excessive Terminal Spread ........................................................
136 Wire Harness Inspection ................................................................ 137 Visual Inspection Hints ............................................................... 137 Jumper Wires ................................................................................. 138 Digital Multimeters .............................................................................. 139 Additional Meter Features .............................................................. 139 Digital Voltmeters ............................................................................... 140 Measuring Pin Voltage ...................................................................
140 Why a Good DVOM is Safe ............................................................ 140 Voltage Drop Measurement ............................................................ 141 Available Voltage Measurement ..................................................... 146 Measuring Voltage Drop by Subtraction ......................................... 147 Digital Ammeter .................................................................................. 150 Series Type Ammeter ..................................................................... 151 Clamp Type (Inductive Ammeter) ...................................................
152 Digital Ohmmeter ................................................................................ 153 Ohmmeter Common Mistakes ........................................................ 153 Audible Continuity Beep ................................................................. 154 Diode Check ................................................................................... 155 Oscilloscope ....................................................................................... 156 PicoScope™ ................................................................................... 156 Section 4:
Topics ................................................................................................. 159 Introduction ......................................................................................... 160 6-Step Diagnostic Process ................................................................. 160 Step #1 – Verify the Complaint ........................................................... 161 6-Step Diagnostic Process Identify the Problem ........................................................................ 161 Does a Problem Exist? ................................................................... 161 Intermittent or Continuous?
............................................................ 162 Step #2 – Determine the Related Symptoms ..................................... 163 Perform a Thorough Operational Check ......................................... 163 How a Circuit is Related ................................................................ 164 How Much of the Circuit is Affected? ............................................. 164 Circuits with Self-Diagnosis ............................................................ 165 Step #3 – Analyze the Symptoms ...................................................... 166 If Entire Circuit is Inoperative ..........................................................
167 If Any Part of the Circuit Works ...................................................... 168 Eliminate Parts of the Circuit .......................................................... 168 Trace the Paths of Current Flow ..................................................... 169 Step #4 – Isolate the Problem ............................................................ 170 iv Technical Training