Remove and replace components in an electric vehicle high voltage powertrain and ancillary systems

Business Sectors (Suites): Electric and Hybrid Vehicles,Maintenance and Repair - Light Vehicle,Maintenance and Repair - Heavy Goods and Public Service Vehicles
Developed by: IMI
Approved on: 31 Dec 2020


This standard covers the competence and knowledge technicians need to safely carry out the removal and replacement of components in isolated high voltage systems in an electric vehicle. High voltage systems include the powertrain and ancillary systems.  It also ensures that the technician is aware of the effect that high voltage component technology has on other vehicle systems.
For the purposes of this standard, an electric vehicle is any vehicle that is in part or wholly electrically propelled. This would include:

  • Hybrid (HEV) - to include mild/micro hybrid vehicles where the voltage is considered dangerous.
  • Plug-in Hybrid (PHEV)
  • Extended Range Electric Vehicle (ER-EV) or Range Extended Electric Vehicle (RE-EV)
  • Battery Electric Vehicle (BEV) or Pure Electric Vehicle (PEV)
  • Fuel Cell Electric Vehicle (FCEV).

Warning: It has been recommended by industry experts that only those with suitable training and experience on working with electric vehicles should carry out the functions below.

Performance criteria

You must be able to:

P1 Identify the electric vehicle type and collect relevant technical information
P2 Wear personal protective equipment (PPE) and use vehicle protection equipment (VPE) appropriate to the work activities you are carrying out
P3 Ensure the vehicle is safe to work on and cannot be started without your knowledge and agreement
P4 Ensure the work area is clearly identified using signs and barriers as appropriate, following environmental standards and regulations at all times
P5 Support your work activities by reviewing:

P5.1 system manufacturer's vehicle technical data
P5.2 removal and replacement procedures
P5.3 legal requirements
P6 Prepare, check and use all the appropriate equipment required following manufacturers’ instructions
P7 Work in a way which minimises the risk of:

P7.1 damage to other vehicle systems, components and units
P7.2 damage to your working environment 
P7.3 injury to yourself and others
P8 Select replacement components which meet the manufacturers’ recommendations or conform to operating specification
P9 Carry out component removal and replacement activities following:

P9.1 manufacturers’ instructions
P9.2 industry recognised repair methods
P9.3 health, safety and environmental requirements
P10 Record and report any relevant/related faults you notice during the course of your work
P11 Use suitable testing methods to ensure the rectified system performs to the vehicle operating specification and any legal requirements prior to return to the customer
P12 Ensure your records are accurate, complete and passed to the relevant person(s) promptly in the format required

Knowledge and Understanding

You need to know and understand:

Use of technical information
K1 How to identify an electric vehicle and its type
K2 How to find, interpret and use sources of information applicable to component removal and replacement within an electric vehicle’s high voltage systems
K3 The importance of using the correct sources of technical information for electric vehicle component construction
Legislative and organisational requirements and procedures *
K4 The health and safety legislation, industry codes of practice or guidelines and workplace procedures relevant to working with electric vehicles 
K5 How to select, check and use appropriate personal protective *
and vehicle protective equipment when working on electric vehicles
K6 How to ensure the environment is safe when working on an electric vehicle
K7 Your workplace procedures for the:

K7.1 referral/reporting of problems when working with electric vehicles
K7.2 how to make others aware that work is being carried out on an electric vehicle
K8 The precautions necessary when using plug-in charging equipment.
K9 How to carry out a risk assessment on damaged and broken-down electric vehicles
K10 How to confirm an electric vehicle is safe to work on and the precautions you should take to ensure the high voltage system cannot be re-energised without your knowledge and agreement
K11 The hazards associated with electric vehicle high voltage components, including batteries 
K12 How to reduce the risk of high voltage hazards when working on and around electric vehicles
K13 The implications of electrical conductivity through the human body 
K14 The implications of strong magnetic fields and the effects on medical devices 
K15 Workplace procedures that must be followed in the event of electric shock 
K16 The hazards associated with electric vehicles when exposed to extreme temperatures, impact and other adverse conditions
K17 How to store, dispose of, recycle and return any removed high voltage components in line with legislative, environmental and organisational requirements
K18 How to work safely avoiding damage to other vehicle systems, components and units and contact with leakage and hazardous substances
K19 The hazards associated with alternative fuel sources and systems, including hydrogen fuel cells

Electrical and electronic principles
K20 The principles of chassis and insulated earth return systems as appropriate to electric vehicles
K21 Basic electrical and electronic principles, including ohms law, voltage, power, current (ac/dc), resistance, magnetism, electromagnetism and electromagnetic induction
K22 Specific high voltage circuit protection
K23 Electrical and electronic principles associated with ancillary systems, including types of sensors and actuators, their application and operation
K24 The interaction between electrical, electronic, magnetic, chemical and mechanical components within electric vehicle systems
K25 The operating principles of electric vehicle components
K26 How electric vehicle systems interact and communicate
Vehicle equipment faults and their correction
K27 How to identify faults and damage in electric vehicle high voltage electrical systems and components
K28 How to remove, replace, test and evaluate the performance of replacement components and the reassembled system against operating specifications and legal requirements
K29 The importance of ensuring components are functioning correctly before release to the customer
High voltage systems and components removal and replacement
K30 How high voltage components function and are constructed, including battery modules, electric motors and associated components
K31 How to identify the components which make up the high voltage electrical system
K32 How to identify the location of high voltage cables and components, for example, by labelling and colour 
K33 The different voltages associated with components in electric vehicles
K34 The manufacturers’ specification for the type and quality of components to be used for replacement
K35 The different types of energy storage systems and voltages associated with electric vehicles
K36 The components of alternative fuel sources and systems on electric vehicles, including hydrogen fuel cells
Use of tools and testing equipment and testing techniques
K37 How to select and use the testing equipment required
K38 How to select, prepare, check and use all the repair and replacement equipment required
K39 How to conduct tests on isolated high voltage systems following safety and workplace procedures
K40 How to conduct a test on energy sources and systems
K41 How to determine the serviceability of a component in a high voltage system
K42 How to interpret the results of your tests and make recommendations based on these results
K43 The importance of basing your recommendations on test results
Vehicle system operation
K44 The main differences between an electric vehicle and a non-electric vehicle and its basic operation, including regeneration 
K45 How to safely operate an electric vehicle
K46 The specific manufacturer’s guidelines and the precautions necessary when charging, connecting an auxiliary power source to or towing/lifting an electric vehicle
K47 How to mobilise an electric vehicle safely
K48 The charging systems (types and modes) associated with electric vehicles and how to charge electric vehicles safely


1. Equipment includes:
1.1. hand tools
1.2. code readers
1.3. special tools, for example manufacturer specific equipment and software
1.4. safe and appropriate electrical testing equipment
1.5. relevant safety equipment 
2. Testing methods include:
2.1. sensory
2.2. functional
2.3. measurement
3. Components include:
3.1. high voltage batteries
3.2. motors/generators
3.3. cabling and wiring
3.4. relays and contactors
3.5. electronic control units, sensors and actuators
3.6. on-board charger and charging port
3.7. isolators
3.8. inverters/rectifiers
3.9. battery management units
3.10. vehicle start/stop control
3.11. driver instrumentation
3.12. multi-battery systems
3.13. drive trains
3.14. power sources
3.15. ancillary systems and components

Scope Performance

Scope Knowledge





This section contains examples and explanations of some of the terms used but does not form part of the standard.
Hazards associated with high voltage electrical vehicle components - exist not only during work on high voltage systems, as specified above, but also on all other high-power electrical drive systems and high-pressure storage systems. Vehicle and equipment manufacturers’ guidance should be followed at all times.
High voltage – Regulation No 100 of the Economic Commission for Europe of the United Nations (UNECE) — Uniform provisions concerning the approval of vehicles with regard to specific requirements for the electric power train, states that: ‘High Voltage’ means the classification of an electric component or circuit, if its working voltage is > 60 V and ≤ 1 500 V DC or > 30 V and ≤ 1 000 V AC root mean square (rms). Electricity at Work Regulations (1989), and associated HSE guidance should be followed at all times.
Sources of information applicable to electric vehicles 
Examples include hard copy manuals, data on computer and data obtained from on- board diagnostic displays.
Sensory testing methods include looking, listening, smelling, touching for temperature or vibration.
Vehicle - any vehicle that is in part or wholly electrically propelled. This would include:

  • Hybrid (HEV) - to include mild/micro hybrid vehicles where the voltage is considered dangerous.
  • Plug-in Hybrid (PHEV)
  • Extended Range Electric Vehicle (ER-EV) or Range Extended Electric Vehicle (RE-EV)
  • Battery Electric Vehicle (BEV) or Pure Electric Vehicle (PEV)
  • Fuel Cell Electric Vehicle (FCEV)

Links To Other NOS

External Links

Version Number


Indicative Review Date

31 Dec 2023





Originating Organisation


Original URN


Relevant Occupations

Auto-electrical Technician (Automotive), Automotive Aftermarket Electrical Enhancement Technician (Automotive), Heavy Vehicle Diagnostic Technician (Automotive), Heavy Vehicle Fleet/Service Manager (Automotive), Heavy Vehicle Master Technician (Automotive), Heavy Vehicle Service Technician (Automotive), Heavy Vehicle Trailer Diagnostic Technician (Automotive), Heavy Vehicle Trailer Fleet/Service Manager (Automotive), Heavy Vehicle Trailer Master Technician (Automotive), Heavy Vehicle Trailer Service Technician (Automotive), Lift Truck Service Technician (Automotive), Lift Truck Trailer Diagnostic Technician (Automotive), Lift Truck Trailer Master Technician (Automotive), Lift Truck Workshop Controller , Light Vehicle Diagnostic Technician (Automotive), Light Vehicle Fleet/Service Manager (Automotive), Light Vehicle Master Technician (Automotive), Light Vehicle Service Technician (Automotive), Mechanical, Electrical and Trim Assistant Technician (Automotive), Mechanical, Electrical and Trim Technician (Automotive), Motorcycle Diagnostic Technician, Motorcycle Fleet/Service Manager (Automotive), Motorcycle Master Technician (Automotive), Motorcycle Service Technician, Workshop Supervisor (Automotive), Bus and Coach Mechanic, Bus and Coach Electrician, Bus and Coach Mechelec, Bus and Coach Master Technician

SOC Code



Electric vehicle: maintenance and repair; electrical components; high voltage;