Tech Tip: Tips for Working on High-Voltage Vehicles

When an electric vehicle comes into your facility for service or repair, it’s important to follow the necessary precautions to help promote proper and safe repair on these high-voltage models. Take a look at the following tips:

Proper Procedures
Preparing to work on a high-voltage system requires wearing the right Personal Protection Equipment (PPE) and taking the proper precautions, including:
  • Wearing safety glasses with appropriate side shields when within 50 feet of the vehicle
  • Using certified, up-to-date Class "0" insulated gloves (with insulated protectors) rated at 1000
  • Removing all metal objects from your person, such as rings and watches
  • Placing safety cones around the vehicle to alert fellow employees that you are working on a high-voltage system
  • Employing the "one hand" rule whenever possible, which means working with only one hand while keeping the other behind your back
  • Conducting a complete inspection of the high-voltage system if the vehicle was involved in a collision

Disable High-Voltage System
Before beginning any service or repairs, the vehicle’s high-voltage system should be disabled. See High-Voltage Disabling in Service Information (SI) for complete, step by step instructions.


A successful GDS2 Scan Tool High Voltage Disable Procedure will open the high-voltage contactor relays and discharge the high-voltage system by setting a crash-event lockout. (Note that when this stage is reached, the Clear Secured High-Voltage DTCs procedure will have to be performed to enable the system again.) Once the system has been successfully disabled, a Procedure Complete message will appear on the scan tool.

If the GDS2 Scan Tool Method does not complete the process or cannot be implemented, a DMM-based physical measurement procedure can be performed with certain high-voltage connectors.

Failure to follow any of the above steps could result in serious injury or death.

For the latest and most up-to-date repair procedures, ALWAYS reference your Service Information (SI) site. For additional tips and safety procedures when working on high-voltage vehicles, see Documents #2409590, #4557023 and #4511265 in SI.

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