With superior mileage and reduced emissions, the Prius had captivated drivers and technicians alike with its hybrid technology. It's one of the few vehicles on the road to attain super ultra low emission vehicle (SULEV) status. The earth-friendly Prius is also the core of Toyota's worldwide Eco-Project, which is based on the philosophy of providing clean, safe and appealing products that are "environmentally friendly." The Prius features the Toyota Hybrid System (THS), which uses two power sources: a gasoline engine and an electric motor. While the Prius features hybrid technology, when it comes to collision reapir, it's not much different from any other vehicle.

Please Note: The Prius contains numerous high-voltage circuits that are capable of producing over 288 volts. Careless servicing of the hybrid system may result in electrocution and could be fatal! If a Prius is brought in for collision repair, review the Prius Emergency Response Guide, along with the proper Repair Manual procedures.

Technicians at some collision repair facilities have expressed concern about how to repair a damaged Prius. You'll need to follow basic precautions - outlined in this article - but in general, as long as the high-voltage electrical system is properly deactivated, repairing the body of a Prius is much like repairing any other vehicle. Keep in mind, though, if mechanical repairs need to be performed or if the high-voltage battery needs to be removed, a specially trained Toyota master technician must perform the service.

THS Operation

Here's how the Toyota Hybrid System operates: The vehicle may be powered by its electric motor while the gasoline-powered engine is not running. In other instances, the gasoline-powered engine can provide the force that mechanically drives the vehicle. Or, the gasoline-powered engine can be used to generate electricity, which powers the electric motor to drive the vehicle and/or is used to charge the high-voltage battery pack.

Besides basic operation of the Prius, you need to be aware of some additional features. This article provides instructions and precautions that will help you set up a safe environment for working on the vehicle.

In the engine compartment of the Prius, the high voltage inverter box displays the Toyota Hybrid System logo on the cover. Also note the orange colored high voltage power cables.

High-Voltage System Identification

All high-voltage wiring is color-coded orange. “High Voltage” caution labels also identify the high-voltage battery pack and other high-voltage components.

• Do not carelessly handle these wires and components.

Disabling the High-Voltage System

You or a certified technician should disable the high-voltage system by disconnecting the negative terminal of the battery prior to performing repairs on the body. Disconnecting the auxiliary battery shuts down the high-voltage circuit to ensure your safety. For additional protection, the service plug can be removed.

• The technician must wear insulated rubber gloves (lineman's gloves) when removing the service plug.
• After removing the service plug, you must wait at least 5 minutes to allow the full discharge of the high-voltage condensers inside the inverter.

If you or a certified technician cannot remove the service plug due to damage to the rear portion of the vehicle, remove the hybrid vehicle (HV) fuse or the ignition control (IGCT) relay instead.

Safety Mechanism

The main relay automatically turns OFF, shutting down the high-voltage circuits under these conditions:

1. Ignition key is turned OFF.
2. The 12-volt power source is cut OFF.
3. The airbag sensor or the sensor in the inverter detects a frontal collision.
4. The grip is pulled up to remove the service plug.

Therefore, in most accidents, the high-voltage system is automatically disabled immediately. In fact, in a severe frontal impact, it's disabled before the airbags are deployed.

In essence, once the high-voltage system is disabled, repairing the body of the Prius is just like repairing any other Toyota, but keep in mind some additional precautions:

• Be sure to disable the high-voltage system by disconnecting the 12-volt battery prior to welding on the body.
• If the vehicle is disabled and cannot be driven, do not push a Prius around the shop - it must be on wheel jacks to be moved.
• If the high-voltage battery pack has been ruptured and battery acid is in the rear trunk area or in any other part of the vehicle, use boric acid to neutralize the spill; then test with litmus paper to ensure it's neutral before attempting to clean it up.

Driving a Prius is somewhat different than driving a typical gasoline-powered car. When you drive one, follow these procedures:

The Prius contains a high voltage hybrid vehicle (HV) battery pack and a low voltage auxillary battery. Located at the base of the trunk behind the rear seat, the HV battery pack contains non-spillable, sealed nickel metal hydride (NiMH) battery modules. The lead-acid, 12-volt auxillary battery is located in the trunk and is grounded to the metal chassis of the vehicle.

Starting the Prius

1. Make sure the parking brake is engaged and the shift lever is in the park (P) position.
   • Unlike conventional vehicles, the gasoline engine will only start when the shift lever is in the P position and will not start in the neutral (N) position.
2. While pressing the brake pedal, turn the ignition switch to the START position and release - the READY light (ready-to-drive indicator light) flashes.
   • If the outside air temperature is low, the READY light may flash longer than usual.
3. Once the system determines the vehicle is ready to be driven, the READY light illuminates steadily and the buzzer emits a beep.
   • After the gasoline engine warms up, it stops automatically, provided that the air conditioning compressor does not need to operate and the high-voltage battery pack is sufficiently charged.

Caution: Unlike conventional vehicles, once the Prius illuminates the READY light, you cannot depend on the sound of the engine running to determine if the vehicle is ready to be driven. Always refer to the READY indicator light to check the status of the vehicle.

Starting Out

1. While pressing on the brake pedal, release the parking brake and move the shift lever to the drive (D) position (the vehicle will move forward just like a conventional vehicle with an automatic transmission).
2. Gradually release the brake and slowly depress the accelerator to start moving.

When starting at extremely slow speeds, the gasoline engine may remain OFF to conserve fuel while the electric motor drives the vehicle, so don't rely on the sound of the engine to determine if the vehicle is ready to be driven. In addition, if the gasoline engine remains OFF during initial takeoff, it will automatically start up when the car reaches approximately 15 mph during acceleration.

Prius Courses

Because Emergency Medical Technicians (EMTs) First Response teams are typically the first to encounter a vehicle after an accident, they may be concerned about how to deal with high-voltage systems. As previously stated, under certain accident conditions, the system automatically disengages so EMTs can approach a damaged Prius just as they would any other vehicle. In addition, to help educate people in the field, Toyota has conducted various courses to familiarize EMTs and educate insurance appraisers with the THS technology.

The University of Toyota is also creating a one-day course for collision centers on how to work on a Prius safely. The course is designed for Toyota dealership collision repair facilities or Toyota-designated independent collision repair facilities. For additional information on this course, please call (310) 468-5572. To contact the Toyota Collision Repair and Refinish Training Centers directly, call the West Caldwell, N.J., training center at (973) 882-6252, or the Torrance, Calif., training center at (310) 468-5719.

The Prius is a breakthrough vehicle that's easy on the environment - and if one gets in an accident, it's easy to repair the vehicle's body, so long as you follow a few basic safety precautions.

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