Automobile Black Boxes: The Electronic Witness

Since the 1970s motor vehicles have come equipped with computers that tell owners when to “Check Engine” and provided diagnostic assistance to the mechanics at the local repair facility. In the years since, and as airbags have become more prevalent in vehicles, the Event Data Recorders (“EDR”) in vehicles have become increasingly more complex in the information recorded. As the data gathered and recorded by the EDR has increased, so has the ease with which that information can be accessed. In 2004, sixty-five percent of all vehicles sold in 2004 contained an EDR and approximately fifteen percent of all vehicles on the road have EDR. As a result, more and more attorneys are faced with an electronic witness whose testimony is often taken as gospel by law enforcement, insurance adjusters, and jurors.

Accessing and Translating the Data

In complex products liability matters where the vehicle manufacturer or airbag supplier is a party, accessing the information and decoding the EDR data is certain to occur. The vehicle manufacturer or airbag supplier will have the software definition document which will allow them to download and interpret all of the hexadecimal data codes recorded in the EDR. Downloading and interpreting the EDR data is quite different when you are dealing with comparatively unsophisticated parties like insurance adjusters and law enforcement personnel.

In a personal injury action where the insurance adjuster is seeking information about your clients’ speed at the time of the accident, or whether they were wearing their seatbelt, it is a larger issue. Currently, the only commercially available system for the download and interpretation of EDR data is manufactured by Vetronix. The Vetronix system includes both the hardware and software to perform the download and translate the EDR data. Vetronix has relationships with GM and Ford regarding the interpretation of the information recorded in hexadecimal code. While Vetronix continues its efforts to establish business relationships with other manufacturers, the fact remains that if the vehicle is not a GM or Ford product, and the manufacturer or component part manufacturer is not a party to the suit, downloading and translating the information into a useable format may be impossible. Vetronix has maintained a relationship with GM since 1994 and currently any GM vehicle with an EDR can be downloaded with the Vetronix hardware and software. Other joint venture vehicles, such as the Isuzu Ascender and Saab 9-7x, which were produced in conjunction with GM, can also be downloaded. The ability to download the EDR in Ford vehicles is not as clear cut. The list of Ford vehicles that can be downloaded changes depending upon the year in which the vehicle was produced. For example, the Ford F-150, the most popular full-size pick-up, can be downloaded by the Vetronix system for model years 2001-2003. However, it cannot be downloaded for 2004 through the present, but for the 2004 Heritage model.

An issue to consider when faced with a request by the insurance adjuster or law enforcement to download the EDR is who owns the data. It is generally accepted that the vehicle owner or lessee is the owner of the information. This position has been adopted by the Alliance of Automobile Manufacturers. If your client has accepted a property damage settlement, the information is now the property of the insurance company. Some courts have required law enforcement to obtain a warrant before allowing the download of the information, but vehicle owners who are unaware of what information may be contained and how that information may be used as justification for increased charges, will often consent to the search.

Establishing a Protocol Before the Download

Prior to any download, a protocol should be established. This is especially important with automobile manufacturers who will have all of the translation information and software. The protocol should require the defendant to, among other things:

(a) Identify the download technician;
(b) Identify the specific data recorder that is to be downloaded;
(c) Describe all of the data recorded by the particular recorder;
(d) Identify the equipment they plan to use for the download;
(e) Disclose the potential to corrupt, add to, or alter data;
(f) Describe and define the meaning of the codes so the plaintiff’s counsel may translate and interpret the data;
(g) Allow photographing and videotaping of each step of the process, including each screen; and
(h) Provide an exact copy of the data and the translation of the data to plaintiff in hard copy and on disk immediately after the download.

There are additional concerns that should be included in the download protocol depending upon the facts of the case. Including whether the vehicle will be powered up, what port will be used for the download, and whether disassembly will be necessary.

When is Information Recorded

There are two types of information recorded by the EDR: (1) non-deployment events; and, (2) deployment events. Non-deployment events, also sometimes called near-deployment events, are when there is an event severe enough to “wake-up” the sensing algorithm, typically a four G (four times its own weight) deceleration. The EDR can store only one non-deployment event. This information will be stored until there is a more severe velocity deceleration, or 250 ignition cycles.

Deployment events are when the sensing algorithm is awoken and based upon the predictive features of the algorithm, it gives the command to fire the airbags. The EDR will record for the five seconds preceding the event and then the first 300ms after the algorithm “wake-up.” Two deployment events can be stored if they occur within five seconds of each other. The initial firing event will be stored in the deployment file, with the secondary event stored in the near deployment file. Ford and some of its suppliers claim that the information is not locked upon deployment and that fault codes can be introduced if downloaded by someone other than Ford. Vetronix claims that the information is locked and cannot be overwritten or cleared.

What Information is Recorded

The amount of information recorded depends upon the make, model, and year of the vehicle. Most EDR will record pre-crash data including: percentage of throttle wide open, vehicle speed, engine speed (RPM), and brake switch status. During the crash pulse, the EDR will record the delta V, or change in velocity, in 10ms increments. It is the delta V along with a variety of algorithms and sensors that predict the severity of the crash and determine whether the airbag should fire or not. Additionally, a system status at deployment table is generated. This table will tell whether the drivers’ seatbelt was buckled, whether the passenger-side airbag was suppressed, the ignition cycles at deployment, and the ignition cycles at investigation. Finally, Vetronix will provide a printout of the hexadecimal data that was downloaded, but that the Vetronix software was unable to interpret. The Vetronix software is able to translate the basic data downloaded from the EDR, but it is unable to translate all of the information available.

Other Issues

The information provided by the download can be impressive, but it is still subject to scrutiny. The first thing that should be looked at is the ignition cycles. The number of ignition cycles at investigation should only be one more than the number of ignition cycles at deployment. If the difference between these two values is greater than one, it can mean that someone else came and attempted a download. This does not necessarily mean that the data was corrupted, but it should send up a red flag that someone else was investigating the crash.

The next issue to consider with regard to the ignition cycles is whether they are listed as zero. For the information to be recorded accurately, the EDR must receive power. If the ignition cycles are listed as zero in the print out, this means the EDR lost power while recording and the information will not be reliable. Vetronix notes this very fact in the notes section at the bottom of its printouts. If there is a loss of power while recording, the information regarding seatbelt use as well as whether the passenger airbag was suppressed can be inaccurate.

It is important to get the hexadecimal translation information when the defense argues comparative negligence. For example, the report may indicate that the airbag warning light was on. The manufacturer will argue that the driver was at fault for not taking the vehicle in to a service center to get the airbag system checked out. However, by translating the hexadecimal codes, you may find that the airbag warning light should have been on, but that the light was inoperable. Accordingly, while the computer had recognized a problem, the warning had not been conveyed to the driver so that it could be acted upon. The information contained in the hexadecimal data allows you to double check the information in the report to determine whether the warnings are actually being conveyed to the driver.


This article is intended to give a brief overview as to what information is gathered, how it is gathered, and what limitations there are. Vetronix continues its efforts to establish relationships with other automobile manufacturers while at the same time it updates the software for the manufacturers it already has relationships with. BMW, Chrysler, Honda, Isuzu, and Toyota all have installed EDR on some models. It is reasonable to anticipate that the electronic witness will appear in more and more cases to provide its testimony.


[1] CNewsome.

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