Prius Gen 2 (2004-2009)

1. 1

   Primary
   OEM Procedure #1 (power button accessible): 1) Chock wheels, set parking brake, push the P switch to engage Park. 2) Check the READY indicator. If it is ON, push the power button ONCE to shut the vehicle off. If the cluster and READY indicator are already OFF the vehicle is already shut off — do NOT push the power button (it may start the vehicle). 3) Remove the electronic key from the key slot. 4) If equipped with smart key, set the smart-key disable button under the steering column. 5) Keep the electronic key at least 16 ft (5 m) away from the vehicle. 6) If the key cannot be removed/found, disconnect the 12V auxiliary battery (rear cargo area). Shutting the vehicle off disables the HV battery pack, SRS airbags, and gasoline fuel pump. There is NO tool-free "service plug" disable in this ERG — the service disconnect on the pack is a dismantling-manual step, not the ERG's responder method.

   Power button + electronic key slot + READY indicator are in the front (dash / center cluster). The smart-key disable button (if equipped) is underneath the steering column (OEM-text).

2. 2

   Backup
   OEM Procedure #2 (power button inaccessible): 1) Disconnect the 12V auxiliary battery in the rear cargo area. 2) Remove the 20A YELLOW HEV fuse in the engine-compartment junction block; when in doubt, pull all four fuses in that fuse block. WARNING (OEM): if neither disable procedure can be performed, proceed with caution — there is no assurance the HV system, SRS, or fuel pump are disabled.

   12V auxiliary battery — rear cargo area, passenger side. 20A yellow HEV fuse — engine-compartment junction block (remove junction-block cover to access).

Note
OEM WARNING (verbatim): "Power remains in the high voltage electrical system for 5 minutes after the HV battery pack is shut off." After disabling, power is maintained 90 seconds in the SRS system and 5 minutes in the HV system. OEM WARNING: "Never touch, cut, or open any orange high voltage power cable or high voltage component." Always verify zero voltage with an insulated meter on the orange cables before any HV contact. Never assume the Prius is off because it is silent — confirm via the READY indicator.

12V location: Rear cargo area, passenger side (OEM-text). Lead-acid 12V battery, grounded to the metal chassis; has a vent hose to vent gases outside the vehicle if overcharged. GEN-2-specific — do not assume engine-bay.

OEM-text: the 12V auxiliary battery "powers the vehicle electrical system similar to a conventional vehicle" and the HV relays are 12V normally-open relays. Because the gearshift and Park are shift-by-wire, if the 12V is discharged or disconnected the vehicle cannot be started OR shifted out of Park (OEM-text). Disconnecting the 12V is part of both OEM disable procedures.

SRS discharge: wait 90s after airbag deployment before touching SRS components.

Pack location: Behind the rear seat, in a metal case rigidly mounted to the cargo-area floor-pan cross member, concealed by a cover in the cargo area (OEM-text). GEN-2-specific location — differs from later Prius generations; do not assume an under-seat layout.

Pack chemistry: Nickel-Metal Hydride (NiMH), sealed, non-spillable modules. OEM-text: pack is 28 low-voltage (7.2-Volt) NiMH modules in series. Electrolyte is an alkaline of potassium AND sodium hydroxide (caustic, pH 13.5). This is NOT a lithium-ion vehicle.

HV cable color:Orange (OEM-text: "Orange colored power cables carry high voltage Direct Current (DC) between the HV battery pack and inverter/converter."). Cables run from the pack under the floor pan to the inverter; 3-phase AC cables then run to the motor, generator, and A/C compressor.

Do not cut:

• Orange high voltage power cables (OEM-text WARNING - "Never touch, cut, or open any orange high voltage power cable or high voltage component")
• HV battery pack / metal case behind the rear seat (OEM-text - "The cover should never be breached or removed under any circumstances, including fire")
• HV inverter/converter, electric motor, electric generator, A/C compressor and their 3-phase AC cables (engine compartment - high voltage)
• Fuel tank and fuel line (OEM-text - fuel tank undercarriage passenger side; fuel line routed along passenger side under the floor pan) - this is still a gasoline vehicle
• SRS components - driver airbag (steering wheel hub), passenger airbag (top of dash), front seat-belt pretensioners (base of B-pillar), optional front-seat side airbags, optional curtain-shield airbags (inside roof rails), SRS computer (floor pan under center console)
• OEM cribbing rule - do NOT place cribbing or rescue lift bags under the high voltage power cables, exhaust system, or fuel system

Reinforcement (UHSS):

• A-pillars
• B-pillars (front seat-belt pretensioners mounted at base)
• C-pillars (rear side-impact sensors at base, if optional side airbags fitted)
• Roof rails (optional curtain-shield airbag inflators)
• Steel unibody (body panels steel except aluminum hood and rear hatch)

Pack piercing risk: The HV pack sits behind the rear seat in a metal case on a cross member, concealed under a cargo-area cover. OEM-text: NiMH electrolyte is absorbed in the cell plates and forms a gel that "will not normally leak, even in a collision"; a breach requires a catastrophic crash that cracks BOTH the metal case and a plastic module. OEM WARNING: the pack cover "should never be breached or removed under any circumstances, including fire" - doing so "may result in severe electrical burns, shock or electrocution." Any tool that penetrates the rear cargo floor can breach a module and expose caustic alkaline electrolyte.

Isolate damaged vehicle 25 ft from exposures.Verify

Live from NHTSA. Cross-check the VIN against nhtsa.gov/recalls before work.

OEM cribbing points are (4) points directly under the front and rear pillars. Do NOT place cribbing or rescue lift bags under the high voltage power cables, exhaust system, or fuel system (OEM-text). Front-wheel-drive vehicle - must be towed with the FRONT wheels off the ground (OEM-text).

Coolant: Engine coolant present (1.5 L gasoline engine + inverter/converter cooling). Toyota Long Life Coolant - type/color not stated in the ERG. The HV NiMH pack itself is air-cooled (no dedicated coolant loop).

Electrolyte color: Caustic alkaline electrolyte of potassium AND sodium hydroxide, pH 13.5, damaging to human tissue (OEM-text). Absorbed in the cell plates as a gel - normally will not leak even in a collision. Color not stated by Toyota; alkaline hydroxide solution is typically clear/colorless. Neutralize a spill with dilute boric-acid solution or vinegar (OEM-text).

If burning, toxic vapors:

• Potassium hydroxide / sodium hydroxide aerosol - caustic alkaline mist (NiMH electrolyte), severe respiratory and eye hazard
• Toxic gases as by-products of combustion (OEM-text - SCBA required in the Hot Zone)
• Carbon monoxide
• Hydrogen gas (NiMH modules vent gases if overcharged/damaged)

Toyota Prius Gen 2 Emergency Response Guide (PDF) →

Last verified 2026-05-31 · mirror

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