Article and photos by Jason Emery
This article addresses some of the features found in the Chevy Malibu Hybrid and Saturn Aura Green Line from General Motors (GM). Unlike the Yukon, Tahoe, and the Escalade, these models operate on a medium-voltage electrical system. Even though no high-voltage system is present in these models, emergency responders still need to abide by proper safety protocols. These models will be discontinued after the 2009 model year because of low sales of these vehicles.
VEHICLE IDENTIFICATION
The external appearance of the Malibu and Aura hybrid is the same as the standard version, with the exception of the special “badging” manufacturers use for identification. In this case, hybrid logos can be found on the trunk (photo 1) as well as on the driver and passenger-side front doors (photo 2). In addition, the Aura also has the Saturn Green Line Logo displayed on the trunk (photo 3).
Dash layouts unique to hybrid vehicles can also be used for identification purposes. A hybrid logo under the speedometer (photo 4), a tachometer with an Auto Stop indicator (photo 5), and a charge and assist gauge (photo6) indicate that the vehicle is a hybrid. Additional hybrid markings can be found in the engine compartment on the 12v battery cover (photo 7) and in the trunk on the 36v battery cover (photo 8).
HYBRID SYSTEMS AND OPERATION
Both vehicles operate on a 36v DC (medium- or intermediate-voltage) system. The Malibu and Aura are considered as a start/stop hybrid system; unlike full hybrids, which use high-voltage electrical power, these types of hybrids do not use their electric motor (also referred to as a starter generator) to provide power to move the vehicle independently of the gasoline engine. Rather, start/stop hybrids realize fuel savings by reducing the amount of time the vehicle spends idling. The alternator and starter have been replaced with a single electric motor that can instantaneously start the vehicle’s engine when needed. The electric motor can also provide an assist to the engine during accelerations.
As with other hybrids, the hybrid battery in the Malibu and Aura is charged through regenerative braking. The electric motor is used to assist in the deceleration of the vehicle, producing electricity which is then stored in the hybrid battery for later use. The medium-voltage cables (36v to 42v DC) are blue (photos 9-10) and run from the engine compartment under the vehicle to the hybrid battery in the trunk. The section found under the vehicle is not colored blue but is encased in a metal conduit.
(8b) Plastic cover is tilted up for better viewing. Click to enlarge
RESPONSE CONSIDERATIONS
Controlling Hazards
Never approach any vehicle involved in an accident from the front or the rear–always approach from the side. This is especially important for hybrid vehicles in which the engine may appear to be off but could simply be in its “Auto Stop” or “ready” mode, which allows the vehicle to move with no warning if the driver were to take his foot off the brake or inadvertently hit the accelerator. Secure the vehicle so it does not move by placing it in park and engaging the parking brake, if possible. Chock the wheels to prevent movement if the damage to the vehicle prevents the above mentioned options.
After the unexpected movement hazard is addressed, it is time to control the medium-voltage electrical and occupant protection systems. This can be achieved by several methods. The first option is to turn the ignition off and disconnect the negative cable assembly from the 12v battery (photo 11). If you need to cut the negative cables, be sure to cut through both of them. The second option involves removing the run/crank relay found in the engine compartment fuse block (photo 12) and then disconnecting both negative cables from the 12v battery. Either of these methods will shut down the 36v hybrid system.
Another method for disabling the 36v system is to open the hinged cover on the hybrid battery disconnect control module. To do this, remove the 10mm hex head bolt that secures the cover to the module (photo 13). After the cover is opened, the spring-loaded disconnect switch will interrupt s the flow of power out of the battery.
Finally, there is a hood ajar switch near the hood latch. If the hood is open when the vehicle is in the Auto Stop mode, it will prevent the engine from starting and will place the vehicle in its “Off” mode. It will not, however, prevent current flow from the hybrid battery as the methods outlined above.
Even after using these shutdown procedures, it is still recommended that you assume the entire medium-voltage system is still energized. At a minimum, the battery will remain energized after the shutdown procedure is completed. If the battery is damaged or exposed, do not attempt to manipulate the battery disconnect control module. Only a trained technician should attempt to do this. In this case it should only be attempted by a trained technician.
Extrication Operations
As with all hybrids, care must be taken not to cut through high- or medium-voltage cables. These wires are not in areas typically considered cut points; be sure to remain vigilant to avoid them. Even though this vehicle uses only medium-voltage cables, cutting the cables presents an arc hazard.
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The response procedures for the Chevy Malibu and Saturn Aura Green are similar to those for the other hybrid models on the road today. Take a moment to look for the presence of a hybrid vehicle and to employ all recommended safety procedures. Also, be sure to review the manufacturer’s Emergency Response Guide (ERG) for additional information.
If you have been involved in an incident involving hybrid or alternative-fuel 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.
Jason Emery has been with the Waterbury (CT) Fire Department for 14 years and is assigned to the rescue/hazmat company. He is an 18-year veteran of the fire service, is 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 lecturer. He is the founder of Emergency Training Solutions, LLC and the lead PowerPoint® designer for the soon to be released Fire Engineering Handbook for Firefighter I & II.
