High Voltage Vehicle Safety Systems

Course ID: AODHVVS001

Recommended Concurrent Training:

High Voltage Safety and PPE (#AODHVS010)



InstructorDr .Mark Quarto

Course Length: 4 modules (each containing approximately 1 hour of instruction)

Course Handbooks Included: 1 digital copy per module

Learning Assessments: Post-module assessments with certificate of completion


This course should be completed before servicing hybrid, plug-in and electric vehicles. These vehicles contain High Voltage DC and AC safety systems that are monitored by vehicle systems controllers that will maintain a safety barrier between the vehicle operator and the vehicle body/chassis to mitigate the possibility of electrical shock. This course will provide the technical information and background to know how these systems operate and effect vehicle operation and driveability.  Ford, GM, Honda, Lexus, Toyota and other popular products are featured in this course.

Course Objectives

By participating in this On Demand Course, you will be able to:

  • Identify High Voltage systems by color code
  • Recognize the construction and operation of Manual Disconnect systems
  • Know the location of the Manual Disconnect
  • Describe the operation of High Voltage Manual Disconnect systems
  • Identify Interlock Safety systems used on High Voltage systems by using circuit diagrams
  • Describe the operation of High Voltage Interlock systems


Course Outline

Part 1:  Manual Disconnect and High Voltage Interlock Systems

  • High Voltage cables and Wire (Orange)
  • Service/Manual Disconnect Systems
  • High Voltage Interlock Systems
  • Active & Passive High Voltage Bus Discharge Systems
  • High Voltage Isolation Fault Systems
  • Collision Detections and High Voltage Systems


Part 2:  High Voltage Isolation Fault Systems

  • Vehicle Safety System Requirements (FMVSS 305)
  • Purpose of Isolation Fault Detection Circuits
  • Vehicle Isolation Fault System & Operation
    • DC Isolation Fault Detection Circuit
    • AC Isolation Fault Detection Circuit
  • Diagnosing Isolation Faults using Scan Tool and Insulation Tool


Part 3:  Active and Passive Bus Discharge Systems

  • Purpose and Location of HV Bus Discharge Systems
  • Circuit Operation of Active Passive Bus Discharge Systems
  • Testing the Active & Passive Bus Discharge Circuits


Part 4:  Insulation Meter Testing of High Voltage Components

  • Active Discharge Operation & Voltage Testing
  • Isolation Faults and Associated DTCs are Common Faults in HV automotive systems
    • Insulation Testing is required to locate Isolation Fault
    • Isolation Fault results in a Loss of Propulsion 
  • Use Vehicle Systems to help locate the Isolation Fault
  • Use Insulation Meter to confirm the fault

At the conclusion of this series, you will know the operation of vehicle High Voltage safety systems, how to test them, why they can cause a no-start condition, and how to test the system with special tools and Scan Tools to identify isolation fault areas for practical application.


Is this online training course for you?

The design and implementation of high voltage vehicle safety systems is a requirement for Technicians that work with vehicle electrification products.  This course will cover the varied safety systems found on contemporary vehicle electrification products, how these systems operate, applications on current products, failure mode effects, how the vehicle is effected, and the associated diagnostics when failure occur.  This course is applicable for any Technician with limited or some knowledge of high voltage vehicle electrification systems or those that need to update their current knowledge or just need a good refresher.   


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