By Jason Emery
The most popular-selling hybrid model on the market today, the Toyota Prius is now entering its third-generation release with the 2010 model (Photo 1). Although it shares many of the same characteristics of the second-generation Prius, there are a few differences, most notably the option of purchasing the solar panel feature that powers a ventilation system to keep a closed vehicle cooler on a warm sunny day. Response concerns surrounding this new feature are addressed in this article as well.
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Vehicle Identification
The Prius chassis, throughout all three generations, was only released as a hybrid. This makes it slightly easier to identify as a hybrid since both the hybrid logos and the model name indicate that you are dealing with a hybrid. The Honda Insight is the only other vehicle that was released solely as a hybrid.
When approaching vehicles involved in an accident, be sure to look for formal indicators that the vehicle is a hybrid or other type of alternative-fueled vehicle. On the Prius III, you will find hybrid badging on the front fenders (Photo 2). On the liftgate, you will find both the Prius logo (left side) and the hybrid logo (right side) (Photo 3). In a rear-end collision, however, these rear-facing badges may become obscured, so always do a complete walk-around of the vehicle.
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On the inside of the vehicle, there are also indicators of a hybrid on the dash area. On the display, you will see the “ready” mode indicator if the vehicle ignition is started and ready to move, even if the gasoline engine itself is shut off (Photo 4). The display also contains information on the current status of the hybrid system with regard to battery charging or discharging. To the right and above the gear selector on the center of the dash, you will also see three “mode” indicators. These include “EV,” “ECO mode,” and “PWR Mode” (Photo 5). Additional indicators can be found inside the engine compartment. Most notably is the hybrid logo on the plastic engine cowling and the orange high-voltage wiring (Photo 6). Responders will also see high-voltage warning labels in this area as well.
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Hybrid Systems and Operation
The Prius III uses a 201.6v high-voltage battery for vehicle propulsion and to power the air-conditioning system. The battery pack is comprised of 28 low voltage (7.2v) cells wired in series. As with other hybrid vehicles, these batteries are “dry cell” and do not pose a significant leak hazard. The high-voltage battery is recharged through regenerative braking or using power taken from the gasoline engine. The Prius is a “full” hybrid and can run either on electric power alone or through a combination of both the electric motor and the gasoline engine, depending on the needs of the vehicle. As mentioned previously, the air-conditioning system is also run off of the high-voltage battery.
Response Considerations
To keep responding personnel safe, never approach a vehicle directly from the front or the rear of the vehicle, as those areas fall into the potential travel path of the vehicle should it start to move. Always approach from the sides, especially when dealing with a hybrid vehicle. The fact that the engine is off might lull responders into thinking the vehicle is off when it could actually be in its “ready” mode. If this were the case, the vehicle could move suddenly if in gear and if the driver removed his foot from the brake or accidentally hit the accelerator. Whenever possible, secure any vehicle by engaging the parking brake, placing the vehicle in park, and shutting off the ignition. Do these steps as quickly as possible to ensure scene safety. Use wheel chocks to initially secure the vehicle, especially if damage doesn’t allow access to accomplish the aforementioned steps. Place the Prius into park by pressing the “P” button just above the gear selector or by shutting off the ignition (Photo 7).
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After successfully securing the vehicle, the next step is to disable the high-voltage and occupant protection systems (SRS). To do this, shut off the ignition by using the power button located on the dash (Photo 8) and disconnect the negative side of the 12v battery found on the passenger side of the trunk (Photos 9a and 9b). To access the 12v battery, remove the trunk flooring panel and the tray underneath. This provides access to the battery cover, which is easy to remove. If the ignition is not accessible, disconnect the 12v battery and then access the engine compartment fuse box. Remove the IGCT fuse (30A green) and the AM2 fuse (7.5A orange) to disable the system (Photo 10). If unsure of which fuses to pull, simply pull them all. Bleed-down times for the high-voltage system can be up to 10 minutes. Bleed-down times for the SRS is about 90 seconds.
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Although not mentioned in the ERG, as with other hybrid models, the Prius comes with a service-disconnect switch on the battery. Access it by removing the rear cargo area flooring panel and tray. Then pull the latch to the left to release, pull it back toward you, and then pull it straight out (Photo 11). This shuts down the connection between the battery and the rest of the high-voltage system. Always keep in mind, however, that the battery remains energized. If the battery is damaged, do not attempt to access the service disconnect lever. In that case, only a trained technician with the proper equipment should attempt this.
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The Prius III is equipped standard with a “smart key” system. Like other Toyota/Lexus models equipped with the system, the vehicle has the ability to detect the key fob when it is in close proximity and allows the driver to unlock the door or start the vehicle without actually taking a key out and inserting it into a receptacle slot (there is no ignition key slot). You must gain control of this key fob and move it at least 16 feet from the vehicle to ensure control over the ignition system. Be sure to ask all occupants if they have a key, as someone other than the driver may also be carrying one. Within the key fob is a hidden metal cut key that slides out; you can use it to access the doors and the trunk if necessary.
One of the most important new features on the Prius III is the optional roof solar panel (Photo 12). Unlike residential or commercial solar panel systems, this system does not operate at a high voltage and does not use any type of storage battery. This solar panel consists of 36 poly crystalline silicon solar cells connected in series and generates a maximum of 27v with a maximum current of 3.6 amps, depending on the outside temperature and strength of the sun. This power is used to run a blower fan contained within the air-conditioning system. The wiring from the solar panel to the blower fan runs down the driver’s side “C” post. Shutting down the vehicle itself does not disable the power being generated by the solar panel; however, current will only flow if the blower fan is turned on. There is no potential for the power generated by the solar panel to backfeed into the vehicle’s 12v circuit, as they are isolated from one other.
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Extrication Operations
There are no specific techniques used on hybrid vehicles, as their basic design principles remain the same as standard chassis vehicles and the high- or medium-voltage wiring is not located in an area that is typically considered a cut point. In the Prius, the high-voltage cable runs down the center of vehicle underneath the passenger side. As is common in newer hybrids, however, very little of the orange cable is actually visible, even if the car is on its side or roof (Photo 13).
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The Prius III comes standard with driver and passenger frontal air bags, a knee air bag for the driver, front seat-mounted side-impact air bags, and curtain air bags. When conducting roof removal operations in an incident where the side curtain air bags have not deployed, consider removing the center of the roof by cutting the inside of the roof rails on both sides of the vehicle while leaving the posts and roof rails intact (Photo 14). This avoids cutting into any portion of the side impact air bag components. Also consider that the inflator for the curtain air bags sit at the top of the “B” posts in the roof rail. This is a sound principle for any vehicles that have undeployed curtain airbag systems when a roof removal is required.
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Roof removals on a Prius with the optional solar panel are slightly different than roof removals on a regular Prius. As previously mentioned, it is not recommended that standard roof removals be conducted on vehicles with undeployed curtain air bags to avoid cutting into the air bags, their inflators, and wiring harnesses. Instead, cut through the center of the roof just inside the roof rails. It is acceptable to cut through the solar panel materials, if necessary. Take care to protect rescuers and occupants from broken glass, material fragments, and dust from the panel’s different layers. Also be aware that you may cut through the energized output wire. Be aware that although not high voltage, the 27v maximum output wire has a higher arc potential than a 12v wire.
If you must do a traditional roof removal (and the curtain air bags have not deployed) you must take the following into consideration. The output wire for the solar panel is run down the “C” post in the same wiring harness as the side curtain air bags. It’s possible that in the process of cutting the post the rescuer could short the solar panel output wire and the curtain air bag wire together, resulting in bag deployment (even if the vehicle battery has been disengaged). If it becomes necessary to cut the post, one of the following actions is recommended:
1. Disable the solar panel output by placing a salvage cover over the solar panel to shut down power output. Fold the cover in half to create two layers of sunlight blocking and make sure it is free of any holes or tears that would allow light through. The output wire will be deenergized immediately.
2. Remove the headliner about the driver’s side rear passenger area and locate the red or blue output wire found under the solar panel. Disconnect or cut either wire to disable the output.
Author’s note: If you have been involved with an incident involving hybrid or alternative-fueled vehicles, contact me at Jason@etsrescue.com. Case studies involving specific incidents will help further educate firefighters on the proper methodology for dealing with hybrids and other alternative-fueled vehicles.
For a more in-depth look at the principles of hybrid vehicles, see “Hybrid Vehicles: Separating Fact from Fiction,” Fire Engineering, July 2009.
Jason Emery has been with the Waterbury (CT) Fire Department for 15 years and is a Lieutenant on the city’s Rescue/Hazmat Company. He is a 19-year veteran of the fire service, a certified fire instructor, and has a bachelor’s degree in fire science from the University of New Haven. He has taught extensively on the subject of hybrid vehicles and is an FDIC instructor. He is the founder of Emergency Training Solutions, LLC and is the lead PowerPoint designer for Fire Engineering’s Handbook for Firefighter I & II (Fire Engineering, 2009).
Subjects: Vehicle extrication, hybrids
