© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois by Russell Krick

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Advanced diagnostics  Vacuum and pressure gauge tests  Vacuum pump tests  Diesel engine testers  Advanced scan tools  Checking computer terminal values  Using a breakout box (Continued)

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Isolating electromagnetic interference  Using a digital pyrometer  Finding temperature-related performance problems  Using a dynamometer  Using an oscilloscope  Engine analyzer (computer analyzer)

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Advanced methods used to troubleshoot difficult-to-locate problems

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Diagnostic Techniques and Tools  By using some advanced techniques and tools, a technician can diagnose the most difficult problems  Some tools that may be used:  vacuum and pressure gauge  scan tool  breakout box  engine analyzer with oscilloscope

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Strategy-Based Diagnostics

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Troubleshooting Chart

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Vacuum Gauge  Measures pressure that is lower than atmospheric pressure  Used for:  fuel pump vacuum tests  vacuum pump testing  intake manifold vacuum testing  vacuum solenoid testing

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Pressure Gauge  Measures pressure that is higher than atmospheric pressure  Used for:  fuel pump output pressure testing  turbocharger boost testing  exhaust back pressure testing

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Vacuum Gauge Diagnosis

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Vacuum-Pressure Gauge Set up to measure boost on a road test

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Used to check vacuum-actuated devices and vacuum diaphragms

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hand Vacuum Pump Connect the pump, pump the handle, and see if the device holds a vacuum

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  A set of pressure gauges and valves used to measure injector system pressure  Measure various operating parameters:  fuel pump pressure and volume  injector operation  lubrication system pressure

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Diesel Engine Testers

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only In addition to retrieving trouble codes, modern scan tools can be used for advanced diagnostic procedures

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Advanced Scan Tool Tests  Snapshot  instantaneous reading of the operating parameters present when a problem occurs  useful when intermittent problems occur  program the scan tool for a road test  when the symptom occurs, capture the data  return to the shop and review the snapshot data

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Advanced Scan Tool Tests  Datastream  “live” electrical values  read the scan tool screen to see computer input and output values

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Advanced Scan Tool Tests  Actuator tests  most scan tools can switch computer- controlled actuators on and off  allows the technician to verify operation  the scan tool can fire an ignition coil, control the idle speed motor, disable a fuel injector, and perform a balance test

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Computer Terminal Voltage Checks  Use a digital voltmeter  Probe between the computer terminals and ground  Do not pierce the wires  Compare the terminal voltages to specified values

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Terminal Voltage Chart

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Allows the technician to check electrical values at specific pins on an ECM or in the system the ECM controls  Inserted into wiring harness at the ECM Breakout Box

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Breakout Box

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Electromagnetic Interference  Occurs when an induced voltage enters another system’s wiring  Sources:  loose, misrouted, or unshielded plug wires  police and CB radios  aftermarket accessories  May cause noise in stereo speakers or a computer-controlled system malfunction

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Isolating Interference  Turn off or disable circuits or devices  remove the alternator drive belt  turn accessories on and off  If the problem goes away, the cause has been isolated  Use an AM radio tuned between stations to probe for sources

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Digital Pyrometer  An electronic device used to measure temperature  engine operating temperature  exhaust temperature—catalytic converter  coolant temperature  sensor temperature  ambient temperature  air conditioning system temperatures

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Finding Temperature- Related Problems Freeze spray on the ECM

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Finding Temperature- Related Problems Heat gun on the ECM

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Dynamometer  Measures power output by loading the engine  Check acceleration, maximum power, and on-road performance characteristics

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Dynamometer Using a five-gas analyzer with a dynamometer

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Oscilloscope  Displays voltages in relation to time  Produces a line on a cathode ray tube or liquid crystal screen

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Oscilloscope Screen A. 25,000 volt scale B. 50,000 volt scale C.Time scale milliseconds D. Time scale degrees

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Scope Sweep Rate  Frequency or time division on screen  Affects the horizontal, or time, measurement  Set to match the waveform frequency to be analyzed  a low sweep rate compresses the signal  a high sweep rate expands the signal

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Ignition Patterns  Primary  low voltage ignition components  the secondary circuit cannot work properly unless the primary circuit is in good condition  Secondary  high voltages needed to fire the spark plugs

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Primary Waveform

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Secondary Waveform

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only A. Superimposed display Patterns on top of each other—checks that all patterns are uniform B. Parade display Patterns side by side in firing order—compares firing voltages C. Stacked display Cylinders one above the other—compares duration of events Scope Test Patterns

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Distributorless Waveform  True spark is on compression stroke  Wasted spark is on exhaust stroke

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Magnetic Sensor Pattern Probe across sensor leads

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hall-Effect Sensor Oscilloscope connection

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Hall-Effect Sensor Pattern The sensor signal frequency should increase as engine speed increases

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Optical Sensor Pattern If the shutter widths vary, the pulse widths vary

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Crankshaft Position Sensor Oscilloscope connection

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Crankshaft Position Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Scope connection Throttle Position Sensor

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only The TPS should produce a smooth curve as the throttle is opened and closed Throttle Position Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only A switching-type TPS should produce a good square wave without ringing Throttle Position Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Scope connection MAP Sensor

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only The digital waveform frequency should increase as engine speed increases MAP Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Analog waveform amplitude should increase as engine speed increases MAP Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Jumpers connect power to the sensor Mass Airflow Sensor

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only As flow increases, an analog airflow meter should produce more voltage Mass Airflow Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only A digital waveform frequency usually increases with airflow Mass Airflow Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Oscilloscope connection Knock Sensor

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Analog waveform Knock Sensor Pattern

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Electronic Fuel Injector Patterns A. Normal B. Stuck C. Open D. Partial short

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Oscilloscope connection ECM Scope Tests

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Reference voltage ECM Scope Tests

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Flight Record Test  Stores the sensor waveforms in a scope’s memory for playback after a road test  Useful for checking an intermittent condition

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Flight Record Test Normal, consistent signal Signal breakdown

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Engine Analyzer  Group of test instruments in a large, roll-around cabinet  scope  tach-dwell meter  volt-ohmmeter  exhaust gas analyzer  May be equipped with a modem to allow communication over telephone lines

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Engine Analyzer

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Analyzer Digital Display Cranking testsRunning tests

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Analyzer Connection Coil separate from distributor Unitized coil distributor

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Distributorless ignition Analyzer Connection

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Direct ignition Analyzer Connection

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Make sure all leads are clear of hot or moving parts Analyzer Connection

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Coil Output Test  Measures the maximum available voltage produced by the ignition coil  Spark plug requires 5–20 kV  Coil should have higher reserve voltage

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Coil Output Test  Run engine at 1000–1500 rpm  Select secondary parade pattern  Note the spark plug firing voltages  Using insulated pliers, disconnect a plug wire (or install a spark tester before startup)  The open circuit should cause one firing line to rise to maximum coil output  Reconnect as soon as possible

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Load Test  Snap acceleration test  Measures the spark plug firing voltage when an engine is accelerated  voltage requirements increase  Set the scope to parade  Quickly open and release the throttle valve  The firing lines should be no more than 75% of coil output, or about 15–20 kV

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cylinder Balance Test  Measures the power output from each of the engine’s cylinders  The analyzer kills the spark of a selected cylinder, allowing the technician to observe and compare the rpm drop  All cylinders should have the same percentage of rpm drop (within 5%)

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only  Checks the engine’s mechanical condition  Measures how much current is drawn by the starter motor as each cylinder goes through its compression stroke  High current means high compression pressure  Low current means low compression pressure Cranking Balance Test

© Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Cranking Balance Test All cylinders have the same compression Lower compression on cylinder 5