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Hybrid Under-Ride Solution

By Paul Bindon and Matt Stroud
The purpose of our previous article was to encourage creative thought about a situation that would normally have a straightforward approach. As the motor vehicle accident (MVA) was evaluated; however, it became more apparent that the technology contained in the vehicle could make reaching the patients in the vehicle more complicated. It was deliberately designed as a tough “what if” scenario, with very specific circumstances involving a hybrid vehicle. We will discuss several ways to approach the situation in this solution. Many thanks to the very knowledgeable individuals who shared their intelligent and practical solutions to the Honda Civic Hybrid under-ride MVA scenario article. 

Examining the Solutions

Many of the submitted solutions assumed that it was possible to disconnect the 12-volt (V) battery. Although this should be an essential part of vehicle immobilization, the 12V battery is in the front of the Honda Civic Hybrid, and the scenario stated that there was no access to this part of the vehicle. This means that the supplemental restraint systems (SRS), hybrid systems, and possibly high-intensity discharges (HID) headlights could still be powered up. (For more information regarding HID headlights, follow this link: http://www.mgstech.net/media/mgs-articles 

Under-ride MVAs often do not deploy the SRS air bags, and you cannot count on an electronic system to automatically disconnect the fuel pump and high-voltage and SRS systems. Note also that not all hybrid vehicles are equipped with an auto disconnect for the high-voltage system linked with SRS deployment. The MVA description stated that the vehicle was on and running. Since the engine is still running, you should expect that an automatic safety disconnect of the vehicle systems has not happened. Ideally, if the driver is able, turning off the ignition would prevent some of these systems from being on and active, it but would not totally eliminate them as potential hazards.
Lifting the trailer using air bags and cribbing is an excellent approach if you have the tools available to do so in a timely manner. Some departments do not have the amount of cribbing necessary or the air bags needed for this type of vehicle removal. If your department does, you have vehicle removal as an option, but only if response time and patient condition allow you the time necessary to perform the extraction. If you do not, this would mean that stabilizing the trailer and the vehicle and then proceeding without removing the Honda would be the best approach.
Here is an alternate approach to the scenario of the Honda Civic under-ride MVA. 

Step One

Stabilize the Honda by using ratchet straps attached to the wheels and routed over the rear of the vehicle, to prevent suspension movement when parts are removed from the vehicle. Stabilize the trailer with available material; you can use cribbing, struts, or even high-lift jacks. Your choice will depend on how level the terrain is and the equipment you have available. 

Step Two

Perform a tunnel operation through the trunk by first removing the trunk lid and interior trunk trim. You will now have a view of the back of the high-voltage (HV) battery housing (photo 1). Now, using cutters or a reciprocating saw, cut away the rear package tray, as seen from the front in photo 2. You will now have a view of the back of the HV battery but still won’t have access to wires, switches, and mounting bolts, which are on the HV battery front, facing the passengers.



Step Three

Still from the back, continuing with the saw, cut down on the outside edges of the battery box, as in photo 2, allowing the HV battery to fall toward you into the trunk. You now have a view of the HV battery with the 12V wires, orange wires, switches, and bottom-mounting bolts visible. Photos 2 and 3 show a Honda Civic HV battery viewed from the front, with the cover plate removed. In photo 3, note the location of the actual HV battery on the driver side of the battery box. The passenger side of the box is used to store the DC/DC converter and HV battery-control systems. Note the location of the 12V system wiring on the driver- and passenger-side bottom corners. The high-voltage orange wires exit the battery box on the passenger-side lower corner.


Step Four

As shown in photo 4, the service disconnect switch is mounted on the front of the battery, and is now accessible. Remove the small bolt on the cover for the service disconnect, and flip the switch from “on” to “off.” This will eliminate the connection of the high-voltage battery to the rest of the vehicle but will not give you a visual indication that anything has happened. 


The high voltage is now contained within the battery itself. Cutting the 12V wire harness on the driver and passenger side will also eliminate any possible computer system connection to the rest of the vehicle, but it also will give no visual indication of effectiveness. Since the orange wires will no longer contain voltage, they can now be cut to remove the high-voltage battery from the vehicle. Continue with extrication as you would with a non-hybrid Honda Civic.
Step Five

Remove the rear seat back. Package the two children from the rear seat area and remove on backboards, if needed. Depending on the vehicle’s roof condition, you may be able to use a hydraulic ram to maximize the space. Use power or manual seat adjustments, if possible, to help access the patients in the front. If no easy adjustment of the seat is possible, proceed with caution to remove the seat back; the vehicle may be equipped with side SRS air bags and seat belt pretensioners that contain pressurized gas cylinders and pyrotechnic charges. Cut the seat cover material; inspect for hazards before cutting the seat frame material. Eliminate power sources for headrest DVD players, power seat motors, and seat heaters before cutting seat SRS wire harnesses. These systems would not be a concern on a vehicle that was first powered down by shutting off the vehicle and removing the 12V battery negative cable. Lower seat removal may be necessary if the patient’s lower extremities are entrapped. Finally, remove the front seat passengers.


Can a tunnel method be used on any hybrid vehicle with a vertically mounted HV battery?
  • Honda Civic Hybrid 03-05
  • Honda Civic Hybrid 06-current
  • Honda Accord Hybrid 05-07
  • Ford Fusion Hybrid
  • Mercury Milan Hybrid
  • Lincoln Mark Z Hybrid

Yes, it can! Once you understand how the technology works, you can easily and safely use the tunnel method to manage this “what if” scenario.

Yes, there are multiple methods that would allow you to safely remove the patients from this vehicle; depending on your unique circumstances, it’s nice to have another option. 

Matt Stroud is a 23-year veteran of Toyota Motor Corporation, a Toyota-certified master diagnostic technician and an ASE certified master diagnostic technician, with 10 years certified in hybrid technology. Matt has completed multiple extrication courses, giving him a strong knowledge base of fire tactics and terminologies. Because of heavy demand from the fire service, Matt founded MGS TECH in 2007 with the goal to teach firefighters/EMS personnel how to safely manage hybrid and new technology vehicle incidents.



Paul Bindon joined MGS Tech in 2008 as a research specialist and on-site trainer and has completed extrication training at the Corona-X seminar. Paul is also an ASE Certified master auto technician with over 23 years experience in the automotive field. He has been employed with Lexus dealerships for the last 16 years, receiving both master diagnostic specialist and hybrid certification through factory training in the latest automotive technologies.


Matt and Paul perform all their own research on new technology vehicles in order to publish MGS TECH’s Hybrid Safety Guide (HRG) and teach the hybrid safety course to firefighters around the country. 



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