I'm about to replace the inverter coolant pump on a 2017 Prius and the high-voltage cables run right over it.

STOP — High-Voltage Safety Sequence for 2017 Prius Inverter Coolant Pump Replacement

Before touching any orange cables:

1. Power Down: Turn off the vehicle and remove the key fob. Wait at least 5 minutes for capacitors to discharge.

1. Disable HV System: Locate the orange service plug in the engine bay (near the inverter). Remove it and secure it away from the vehicle. This de-energizes the high-voltage system.

1. Verify De-energization: Use a multimeter set to DC voltage to test across the inverter terminals. Confirm 0V before proceeding.

1. Wear PPE: Use insulated gloves rated for 600V+ and safety glasses.

1. Avoid Contact: Never touch orange cables or connectors directly. If you must move them, ensure the service plug is removed and the system is confirmed dead.

1. Coolant Precautions: The coolant itself is not electrically conductive when the system is off, but residual pressure may exist. Relieve pressure slowly.

Important: If you're not a certified hybrid technician, consider hiring one. The high-voltage system can retain lethal charges even when powered off.

Code Reference: Follow NFPA 70E and manufacturer-specific procedures. Toyota recommends using only OEM or equivalent replacement parts.

Proceed only if you're trained and equipped. If unsure, stop and consult a professional.

Exact HV Safety Sequence for 2017 Prius (Gen 4) Inverter Coolant Pump Replacement:

1. Key OFF & Remove: Power off. Remove Smart Key fob ≥16 ft (5 m) away.
2. 12V Battery Disconnect: Remove negative (-) terminal first (10mm). Isolate terminal. Wait ≥5 minutes for HV capacitor discharge (per Toyota TIS RM 1000).
3. Service Plug Removal (Critical): Locate plug under rear seat cushion (driver side) or trunk floor panel. Pull yellow lever straight up to unlock. Pull plug straight out (do not twist). Immediately install Lockout/Tagout (LOTO) device on plug receptacle. Keep plug in your pocket.
4. Verify Zero Voltage (Mandatory): Use CAT III 1000V / CAT IV 600V rated DMM (Fluke 117/87V or equivalent). Test DMM on known live 12V source first. Measure DC Voltage at inverter high-voltage terminals (under inverter cover) or service plug contacts: Must read < 5V DC. Test DMM again on 12V source.
5. PPE: Wear Class 0 (1000V) rubber insulating gloves (leather protectors over) + ARC-rated face shield/glasses + cotton/wool clothing (no polyester). Inspect gloves for pinholes (air test).
6. Proceed: Only now remove orange cable covers/bolts (10mm/12mm) to access pump.

Code/Ref: OSHA 1910.269 / NFPA 70E Art. 120 / Toyota TIS RM 1000 (Hybrid System) / SAE J1766. Never rely on key-off alone. Capacitors hold lethal energy. If DMM reads >5V, STOP – contact Toyota dealer.