What indicates that the HV system is in a safe state for maintenance?

• A. HV service disconnect is OFF and locked out, with energy zero confirmed per OEM procedures.
• B. All dashboards are dim.
• C. The high voltage cables glow.
• D. The 12V battery is removed.

Answer: (A)

The essential idea is that maintenance can only begin once the high-voltage system is truly isolated and has zero energy. The best indicator is that the high-voltage service disconnect is OFF and locked out, with energy zero confirmed according to the vehicle maker’s procedures. This shows the main energy source is physically disconnected, the disconnect is secured to prevent re-energizing, and a proper verification step proves there is no remaining stored or residual energy in the system, including capacitors.

Other options don’t provide that guarantee. Dimmed dashboards don’t prove the HV system is de-energized and can occur for unrelated reasons. Glowing high-voltage cables signal an energized or fault condition, not a safe state for work. Removing the 12V battery also does not ensure the HV circuit is isolated or energy-free, since HV components can remain energized or retain stored energy even when the 12V system is disabled.