Vermont Center for Emissions Repair and Technician Training


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VCERTT, Vermont Center for Emissions Repairs and Technician Training

Our training classes provide theory and hands-on skills in understanding OBD II, diagnosing problems detected by OBD systems, and veryfying repairs. We are continuing to develop classes to meet your needs.

To sign up for a training class contact Corie Dunn at:
Phone: 802-828-1288

Our class descriptions follow. Please see our Schedule page for dates and times.





Advanced Engine Performance Diagnostic Strategies

This workshop applies practical, real-world tests to quickly isolate a root cause for drivability and trouble code faults. Traditional diagnostics require technicians to "check the basics," but that can result in hours of compression, vacuum, fuel pressure/volume and other time-consuming tests.This workshop was developed to provide technicians with a focused approach that will help drill down along the most effective diagnostic path. The workshop will cover the latest tools like transducers and processed scan tool functions, but will also include great ways to get results using the scan tools and traditional equipment normally found in the shop. These strategies can also be used for no-starts, and most trouble code diagnostics and emissions faults as well, so this is a workshop that will provide proven techniques for trimming the diagnostic path and increasing repair effectiveness.  

 ·     Engine breathing tests, including volumetric efficiency (VE)
 ·     VE mapping and crankcase pressure
 ·     Engine fueling tests, including Fuel Trim by conditions
 ·     Rear Fuel Trim, and VE relationships
 ·     Simplified cylinder contribution
 ·      Misfire detection strategies and root-cause analysis



Vehicle Networks and Programming

This workshop covers network voltage, frequency, resistance, and wave form activity; and solutions to elusive faults as well as case studies illustrating techniques and design processes. This workshop will also include extensive coverage of OEM-specific, generic CAN and other vehicle networks connected to the data link connector (DLC). Programming and reprogramming of networked modules will be discussed in detail. There are many options for programming and most involve specific instructions, but many things can go wrong in the process, so this workshop includes some best practices for technicians to consider. 

 ·     Evaluating the best information, including hidden module calibration information
 ·     Non-standard programming
 ·     Voltage supply and module isolation strategies to prevent programming faults
 ·     Module recovery for failed programming 

Hybrid Vehicle Diagnosis and Repair

This workshop is based on experience with actual maintenance issues, trouble codes, costly diagnostic mistakes, specific failure patterns and other "in the trenches" information. This workshop focuses on Toyota and Ford hybrid systems, addressing the hybrid diagnostic and repair challenges technicians are most likely to face, and covers as many testing options as possible so that technicians have a diagnostic path forward regardless of the level of their equipment. Included are many known good scan tool and lab scope examples from the most problematic systems, as well as some great fault examples such as:
 ·     High voltage battery failures
 ·     Low voltage faults causing misleading codes and symptoms
 ·     Prius coolant storage, HC storing catalysts, and exhaust-heated cooling systems
 ·     Engine no-start, no-crank, misfire, whining, rumbling, and other diagnostic tips

Intermittent Electrical and Drivability Diagnostics

This workshop covers diagnostic strategies for successfully working through intermittent electrical problems. Many diagnostic strategies first call for duplicating the symptom or code, and this can lead to frustration. However, faults are usually present and measureable even if the symptoms or codes are intermittent, so this workshop discusses a repeatable strategy for flushing out these elusive faults. The workshop includes tools and tests for isolating faults and validating repairs, including: 
 ·     Customer and technician worksheets
 ·     Best practices for voltage measuring tools
 ·     Largely unused DMM features and functions
 ·     Specific scan tool tips 
 ·     Tools for circuit isolation, fault isolation, and load substitution
 ·     Tool limitations and traps
 ·     Case studies for reinforcement

Advanced Engine Electronic Control Systems

This class reviews electrical circuit theory of operation for thorough understanding of dynamic circuit analysis and advances the partcipant through input signal and output control Frquency Modulation (FM) and Pulse Width Modulation (PWM) with emphasis on emission control systems. Demonstrations are used to reinforce classroom discussions and are designed to increase diagnostic and repair effectiveness. 
 Course Focus:
·     Electrical Wiring Diagrams (schematics) Utilization for Determining System and Component Operation
·     Digital Multi-Meter (DMM) and Digital Storage Oscilloscope (DSO) Usage for Dynamic Circuit Measurements
·     Voltage and Amperage Signal Pattern Discussions and Demonstrations for FM and PWM input and outputs
·     Comparison Between Scan Tool Data and Live Circuit Measurements


OBD II Three-way Catalytic Converters: Operation, Fault Diagnosis and Repair Verification

This class provides an overview of three-way catalytic converter operation and details the monitoring requirements and strategies used by vehicle manufacturers to determine catalyst efficiency. Diagnostic and repair verification procedures are identified for the Steady Cruise and Oxygen Storage Capacity monitoring methods. This updated class covers proven diagnostic procedures and strategies that will help enable fast, accurate and complete decisions related to P0420 codes and other related emissions control issues that can contribute to a catalytic converter efficiency trouble code. In addition, emission system warranty coverage for both California and federally certified vehicles is detailed, and replacement options for catalytic converters are discussed.
 Course Focus:
·     Catalyst Construction and Operation
·     Catalytic Converter Failure Modes
·     Diagnostic Testing Choices (Traditional Converter Testing vs Advanced Converter Testing)
·     Engine and Engine Management Verification
·       Emission System Warranty Coverage
·       Catalytic Converter Replacement Options


Advanced Drivability Series: Oxygen Sensor and Air/Fuel Ratio Sensor Operation, Diagnosis and Repair Verification

This class identifies the different types of exhaust oxygen sensors presently in use including the Critical Current and Ion Pump Air/Fuel Ratio Sensors as well as the typical Stoichiometric O2S. Unique operating characteristics and circuit configurations of the different Air/Fuel Ratio Sensors are discussed. Use of Lambda values derived from scan data is also thoroughly detailed. OBD regulations and vehicle OEM monitoring strategies for each type of O2S are detailed along with diagnostic and repair verification procedures. Discussion on how Readiness Codes should be used for repair is also included. Use of vehicle OEM web available service information is also incorporated to help increase diagnostic efficiency by familiarizing participants with common and unique features of OEM service information websites.

 Course Focus:

·         O2S Monitoring Requirements (factors determining system advancements)

        ·         O2S Systems, Monitoring Strategies and Operation

        ·         O2S Diagnostic Trouble Codes (DTCs), and Operation

·         Scan Tool Retrieval of O2S information using Service Modes $01, $02, $03/$07/$0A, $05 & $06, and $09  (including In-Use Performance

·          O2S Diagnosis and Repair Verification

·         Readiness Codes 


OBD II Evaporative  Emission Control Systems: Operation, Fault Diagnosis and Repair Verification

This class details applicable OBD II requirements and Evaporative Emission Control System (EECS) monitoring strategies used by vehicle manufacturers including the Fuel Tank Vapor Pressure Fluctuation, Purge Pressure Differential, Leak Pump and Engine Off Natural Vacuum detection methods. Enable criteria parameters are discussed and correlated to the various monitoring strategies. Supporting live on-car demonstrations are designed to familiarize the workshop participant with the components of the EECS system, to overview and support a complete understanding of the tools necessary to diagnose the problem, as well as general and specific diagnostic and repair verification procedures.

Course Focus:

·         EECS Monitoring Requirements and Components

·         EECS Systems, Monitoring Strategies and Operation

·         EECS DTCs and Operation

·         Scan Tool, DVOM and DSO Diagnostics

·        System Diagnostics (Leak testing, PCM Component Control, System-specific Component Testing, Diagnostic Tools, Case Studies)


Advanced Drivability Series: Engine Misfire - Monitor Operation, Condition Diagnosis and Repair Verification


This class details engine misfire monitoring requirements and strategies used by vehicle manufacturers to detect and identify engine misfire conditions. Monitoring strategies discussed include the Crankshaft Fluctuation and Secondary Voltage Ion (2VI) detection methods.  Generic and manufacturer specific misfire Diagnostic Trouble Codes (DTCs) are identified along with diagnostic and repair verification procedures. Root causes of engine misfire are also thoroughly discussed. Use of vehicle manufacturer web available service information is also incorporated to help increase diagnostic efficiency by familiarizing participants with common and unique features of manufacturer service information websites.
Course Focus:
·    Misfire Monitoring Requirements, Strategies and Operation
·    Misfire DTCs and Operation
·    Scan Tool Retrieval of Misfire Information using Service Modes $01, $02, $03 & $07, $06
·    Misfire Diagnosis and Repair Verification


Advanced Drivability Series: OBD II Fuel Trim - Operation, Diagnosis and Repair Verification

 This class details the various fuel delivery system monitoring requirements and strategies used by vehicle manufacturers to determine if the desired air/fuel ratio is being met. Rear Oxygen Sensor and Individual Cylinder Fuel Trim Systems are also covered. Generic and manufacturer-specific fuel trim diagnostic trouble codes (DTCs) along with diagnostic and repair verification procedures are identified. Use of vehicle manufacturer web available service information is also incorporated to help increase diagnostic efficiency by familiarizing participants with common and unique features of manufacturer service information websites.


Course Focus:
·    Fuel System Monitoring Requirements, Strategies and Operation
·    Fuel System DTCs and Operation
·    Scan Tool Retrieval of Fuel System Information using Service Modes $01, $02, $03/$07/$0A, $06
·    Fuel System Diagnosis and Repair Verification






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