High-Voltage System Identification, Disabling, and Verification
Identification
Know where the HV components live before you touch anything: traction battery, service disconnect or HV fuse, inverter, DC-DC converter, charger, A/C compressor, PTC heater, and the orange (or manufacturer-specific) cabling that ties them together. Locate the service disconnect/service plug, the 12 V battery, and the OEM's recommended lifting and barrier points. Use the service information to identify any circuit that stays live after shutdown, such as battery-internal modules or certain junction points.
Disabling (lockout/tagout)
Follow the OEM procedure: power down, remove the key/fob to at least 5 m, disconnect the 12 V negative (on many vehicles), then remove the service disconnect or command "service mode" with the scan tool where required. Apply your lock and tag. Wait the specified discharge time-typically 5–10 minutes-for inverter capacitors to bleed down.
Verification
Verify absence of voltage at multiple points, not just one: battery output terminals, inverter DC bus, and any connector you will open. Use the prove–test–prove method with a CAT III/IV meter.
Traps
Pulling the service plug but not waiting; verifying only one test point; assuming the 12 V disconnect kills HV; assuming the scan tool's "service mode" alone de-energizes everything; and reinstalling a service plug before the system is reassembled. Remember that a spinning drive motor can generate voltage even with the pack disabled.
Rule of thumb
No wait time, no work. If the OEM says 10 minutes, wait 10 minutes, then verify at every point you will touch.