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Event Data Recorders: They’re Watching Your Driving

Event Data Recorders in Cars
Event Data Recorders are Watching

Event Data Recorders lurk inside up to 90% of all new cars, ready to store data on a crash.

You’re cruising along, mind half on the road and half on life events.  If you’re like most people, you don’t even know the event data recorder is hard wired under the hood of your car.  At one time auto makers denied putting them in cars.

Manufacturers build event data recorders into the mechanical and electrical infrastructure of the car.  They are not to be confused with the telemetric devices insurance companies persuade some drivers to put in their cars in hopes of lowering rates.  We wrote another blog article on those gizmos.

The Event Data Recorder or EDR first started as an electronic device that stored information from the air bag system in sensing and deploying air bags in a crash.  Different auto makers produced and installed their own devices so no standard existed for how and what type of information was captured.

Evolving Standards for Event Data Recorders

Car makers got away with hiding the devices by calling them names like sensing and diagnostic modules. The device was and often remains part of the air bag sensing electronics.

Federal regulators, always seeking control, came up with guidelines requiring uniform standards.  The first set of rules came into existence in 2006.  The rules targeted information usable in crash investigations.  The rules also sought to monitor performance of auto safety equipment.

“Event data recorder (EDR) means a device or function in a vehicle that records the vehicle’s dynamic time-series data during the time period just prior to a crash event (e.g., vehicle speed vs. time) or during a crash event (e.g., delta-V vs. time), intended for retrieval after the crash event. For the purposes of this definition, the event data do not include audio and video data.”

49 Code of Federal Regulations Sec. § 563.5

At that point, with federal watchdogs overseeing the design and installation of event data recorders in cars, the auto industry had trouble hiding the recording hardware in your new car.

New regulations applied to all new cars made on or after September 1, 2012.

What Information Do Event Data Recorders Store?

Most new cars come with EDRs.  Auto industry insiders admit that 96 percent of all new cars sold in the U.S. now include an EDR.  What are they watching?

  • Engine speed.
  • Whether seat belts were fastened.
  • Vehicle speed.
  • To what extent the accelerator pedal was depressed.
  • Transmission shift lever position.
  • How far (if at all) the driver was depressing the brake pedal.

No law requires auto manufacturers to embed EDRs in new vehicles.  But if they do, and most do, the device must track 15 specific data points including those above.

Is the Event Data Recorder like an Airplane’s Black Box?

Most people know about the “black boxes” in airliners.  Despite the name they actually feature bright orange paint to help crash investigators find them after a disaster.  The Cockpit Voice Recorder stores up to two hours of conversation and sound inside the cockpit before the crash. Older versions only kept 30 minutes.

The other “black box” on an airliner goes by the name Flight Data Recorder.  It records literally hundreds of kinds of information including airspeed, instrument settings, altitude and much more.  All of this helps investigators piece together what caused a plane crash.

By contrast the auto “black box” typically creates only about five seconds worth of data.  Remember, the event data recorder started out as part of the seat belt sensor mechanism.  So forces that trigger the air bags also trigger the reporting function of the EDR.  Some of the devices store information continuously in loop fashion, overwriting data as you drive along.  When there’s a crash or “event” the brief report is generated.  Think of the instant data capture as a snapshot.

Are Event Data Recorders The Same in All Vehicles?

Each vehicle manufacturer designs its own EDR.  No standard applied to manufacture and installation of EDRs.  That’s why regulators stepped in hoping to find a way to control the chaos.

Car makers design vehicles competitively and secretly so the final product can include various other data “modules”.  They may include power train modules, engine control modules, air bag control modules and sometimes even body control modules.  The infotainment system in many cars provides recorded data.  This can include data not only from the entertainment system but also in-dash instrument information, hands-free devices, and built-in GPS and wi-fi devices.

Event Data Recorders in Commercial Drivers

Our focus to this point centers entirely on passenger cars.   Heavy trucks and buses include their own type of data recorders.  Engine Control Modules or ECMs record data including trip and event information, record of last stop, engine use, heavy braking, engine RPM, and steering input.

These devices create a data readout known as a histogram, a graphical representation showing the data outlined above in a form normal people can read.

Different commercial vehicles now employ various other systems.  Trucks and buses often have digital video recorders and GPS monitoring.  Sometimes manufactured directly into the vehicle, other times installed by the new owners and operators, these can include cell phone use monitoring and other high tech data recording.

Who Gets Access To Event Data Recorder Data?

Extracting data from EDRs presents several challenges.  First, the info often appears in what’s called hexadecimal coding.  This consists of a two-digit string of characters using numbers between zero and nine and letters between A and F.  So, the average person and even the average auto shop both lack the equipment needed to properly download the info in a usable form.

Challenge number two asks the question who can access EDR info.  Laws in many states attempt to answer the question.  New Hampshire and Massachusetts passed laws on event data recording devices in motor vehicles.  These laws clarify that any data recorded on EDRs in cars registered in those states is the property of the vehicle owner.  So, the laws for the most part hold that no one has access to the information without consent of the owner.  But like nearly all laws, there are exceptions, which include the following:

  • Court Order
  • Repair shops may download for diagnosing, servicing or repairing the motor vehicle
  • Emergency responders
  • If the device is capable of transmitting information that fact must be disclosed to the owner

What Cars Have Event Data Recorders?

Finally, as we pointed out above most car owners do not realize auto “black boxes” exist.  Many manufacturers at least early on denied that such equipment existed in their cars.  In our research we even found the statement that no list exists showing what vehicles have EDRs.  There is a list and though not current to the most recent year, here is the list of cars with EDR “Black Boxes”.

EDR black boxes exist but the technology and the law continue to evolve.  In major accident cases the data may or may not give useful perspective to what happened.  But remember that the EDR records over itself.  So, in drive-away accidents, the information most likely has vanished.

Photo Credit: Acceleration, by Nikos Koutoulas, on flikr, under license from Creative Commons.


Decoding What’s in Your Car’s Black Box, Edmunds, July 22, 2014.

Retrieving Electronic Crash Data, Trial, February 2018.

U.S. DOT Proposes Broader Use of Event Data Recorders to Help Improve Vehicle Safety, NHTSA publication 46-10, December 7, 2012.

2 thoughts on “Event Data Recorders: They’re Watching Your Driving”

  1. Thanks for your valuable resources. Keep sharing the information like this.
    Aronberg Law Firm, Florida

  2. If I am not mistaken, the radar guns the cops use do not make a time/geo stamped record of speeds (Why is that!? Why no “dashcam” or “body cam” equivalence of a radar gun?) So, unless one asks to see the speed registered on the gun (and even then you don’t know it was your speed), there is no forensic evidence of speeding.

    Since (at least in our state), the law enforcement agency is only required to prove by the preponderance in the civil matter of speeding (51% belief in guilt), it is, therefore, most often the word of the cop against the word of the driver. I presume the vast majority of cops are honest, but not having a record of registered speeds leaves the public vulnerable to abuse or racial bias, not to mention human error.

    Two remedies should apply: Cops should record the speed monitoring activity and EDR speed records (which belong to the owner!) should be readily available to the owner.

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Attorney Myers is a member of the American Trial Lawyers Association, Massachusetts Academy of Trial Lawyers, and New Hampshire Trial Lawyers Association. The Law Offices of Andrew D. Myers offer a broad range of legal services in personal injury cases in Massachusetts (MA) and New Hampshire (NH) areas.

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