I-CAR - Inter-Industry Conference on Auto Collision Repair Certified Electric Vehicle Repair Safety Questions and Answers — Questions and Answers
Question 1: A technician is preparing to disable the high-voltage system on an electric vehicle. After turning off the ignition, removing the key fob, and disconnecting the 12V battery, what is the critical next step before physically touching any high-voltage components?
- Use a CAT III-rated multimeter to verify zero voltage at a high-voltage connection point.
- Remove the main high-voltage service disconnect plug. (Correct answer)
- Visually inspect all orange cables for damage.
- Put on a standard pair of mechanic's gloves for protection.
Correct answer: Remove the main high-voltage service disconnect plug.
After powering down the vehicle and disconnecting the 12V battery (which controls the HV contactors), the next required step is to physically isolate the high-voltage battery from the rest of the system by removing the service disconnect. Only after removing the disconnect and waiting the OEM-specified time for capacitors to discharge should a technician verify zero voltage with a meter.
Question 2: When working on or near any high-voltage component of an EV, what is the minimum class of insulated rubber gloves that is generally required according to I-CAR and industry standards?
- Class 1 (11,250V DC rating)
- Class 00 (750V DC rating)
- Class 0 (1,500V DC rating) (Correct answer)
- Class 2 (25,500V DC rating)
Correct answer: Class 0 (1,500V DC rating)
Class 0 insulated rubber gloves are the generally accepted standard for working on modern electric and hybrid vehicles. They are rated for a maximum use of 1,000V AC or 1,500V DC, which provides the necessary protection for the typical 400-800 volt systems found in EVs.
Question 3: A collision-damaged EV arrives at the shop. The high-voltage battery case appears dented, and a faint, unusual sweet chemical odor is present. What is the MOST appropriate immediate course of action?
- Immediately push the vehicle inside the shop to begin the estimate.
- Use a floor jack to lift the vehicle and get a better look at the battery.
- Connect a scan tool to check for battery-related diagnostic trouble codes.
- Isolate the vehicle in a designated outdoor area at least 50 feet away from any buildings or other vehicles and notify management. (Correct answer)
Correct answer: Isolate the vehicle in a designated outdoor area at least 50 feet away from any buildings or other vehicles and notify management.
A dented battery case and an unusual odor are signs of potential internal battery damage, which can lead to a hazardous thermal runaway event. The correct safety protocol is to immediately quarantine the vehicle in a safe, isolated outdoor location, at least 50 feet from structures and other vehicles, and then inform a supervisor to enact the shop's emergency response plan.
Question 4: Which of the following is the primary purpose of a "Lockout/Tagout" (LOTO) procedure when servicing an electric vehicle?
- To document the technician who is working on the vehicle.
- To prevent accidental re-energization of the high-voltage system while it is being serviced. (Correct answer)
- To secure the vehicle's wheels and prevent it from rolling.
- To alert the vehicle's owner that high-voltage repairs are in progress.
Correct answer: To prevent accidental re-energization of the high-voltage system while it is being serviced.
The core purpose of Lockout/Tagout is to ensure that hazardous energy sources, such as the high-voltage battery, are isolated and cannot be accidentally turned back on while a technician is performing repairs. A personal lock and tag are affixed to the energy-isolating device (like the service disconnect) to provide a physical barrier to re-energization.
Question 5: A technician has properly disabled an EV's high-voltage system, removed the service disconnect, and waited the manufacturer-specified time. What is the mandatory final verification step before any repair work on HV components can begin?
- Check the dashboard for any warning lights.
- Listen for the sound of high-voltage contactors disengaging.
- Perform a "live-dead-live" test with a CAT III or higher rated voltmeter to confirm zero voltage. (Correct answer)
- Ensure the 12V battery reads below 12.0 volts.
Correct answer: Perform a "live-dead-live" test with a CAT III or higher rated voltmeter to confirm zero voltage.
It is never safe to assume a high-voltage system is de-energized. The final, mandatory step is to use a properly rated voltmeter (CAT III or higher) to test for voltage between the high-voltage positive and negative terminals, and between each terminal and the chassis ground, to confirm a reading of zero volts. The "live-dead-live" method, where the meter is tested on a known live source before and after the test, confirms the meter is working correctly.
Question 6: Which of the following safety components is designed to automatically isolate the high-voltage battery from the rest of the vehicle's systems in milliseconds if a high-voltage connector is improperly disconnected?
- The service disconnect plug
- The manual maintenance switch
- The High-Voltage Interlock Loop (HVIL) (Correct answer)
- The pyro-fuse disconnect
Correct answer: The High-Voltage Interlock Loop (HVIL)
The High-Voltage Interlock Loop (HVIL) is a low-voltage safety circuit that runs through all high-voltage connectors. If any of these connectors are opened or compromised, the HVIL circuit is broken, signaling the battery management system to immediately open the main contactors and de-energize the high-voltage system, preventing electric shock.
