ASE G1 Auto Maintenance and Light RepairMaintenance and Light RepairHard
A technician is inspecting a hybrid electric vehicle (HEV). Which of the following safety precautions is MOST critical before performing any service on the high-voltage system?
- AEnsuring the vehicle is in 'Park' with the parking brake engaged.
- BDisconnecting the 12-volt auxiliary battery.
- CLocating and disabling the high-voltage (HV) interlock system.
- DWearing safety glasses and gloves.
Show answer & explanationAnswer & explanation
Correct answer: C. Locating and disabling the high-voltage (HV) interlock system.
Disabling the high-voltage interlock system is the most critical step to de-energize the high-voltage battery and prevent electrocution when working on an HEV's high-voltage components. While other precautions are important, this directly removes the primary hazard.
Why the other options are wrong
- A. Ensuring the vehicle is in 'Park' with the parking brake engaged is a general safety procedure for preventing vehicle movement, but it does not address the high-voltage electrical hazard.
- B. Disconnecting the 12-volt auxiliary battery is important for preventing electrical shorts and unexpected component activation, but it does not de-energize the high-voltage system itself.
- D. Wearing safety glasses and gloves is a general safety practice for all automotive work and insufficient for the specific dangers of HEV high-voltage systems.
HEV High-Voltage Safety
Specific procedures and precautions required to safely work on the high-voltage components of hybrid and electric vehicles.
- High voltage systems can deliver lethal shocks.
- Always wear appropriate PPE, including insulated gloves.
- The primary safety step is to disable the high-voltage system via its service disconnect.
- Verify system is de-energized before beginning work.
Memory trick: Before touching the power, pull the plug to prevent a shock.