EDR Research

CRASH DATA RETRIEVAL 101

The Event Data Recorder (EDR) Explained

The most important thing to understand about the Bosch CDR Tool is that it does not record vehicle data by itself. It is an external tool that retrieves, downloads, or “images” the data captured by an in-vehicle EDR. The EDR is installed inside the vehicle by car manufacturers (OEMs) — and while inclusion of an EDR is not mandated by law, most vehicles sold in the U.S. include an EDR unit.

In most cases, the EDR is a function of a vehicle’s Airbag Control Module (ACM). Since 1999, all new vehicles sold in the U.S. have been required to include driver and passenger airbags. The ACM is the “brain” of the airbag system. It determines when and whether the vehicle should deploy its airbags, based on split-second sensor readings and technical data from the vehicle.

The EDR is a secondary function of the ACM and the car’s safety system. It is often referred to as a “black box” for motor vehicles, as there are functional similarities between the device and the flight recorders found in aircraft. However, there are important differences between the EDR and the recording devices used in the aerospace industry.

For one thing, the EDR only records vehicle data in certain circumstances – and when it does, it only records data for a few seconds. In contrast, an aircraft flight recorder is “always on,” recording for the duration of a flight. Aircraft safety systems also frequently record voice communications from the flight deck, while the EDR currently does not record audio, video, or images from inside the vehicle. It only records raw data from a motor vehicle’s instruments and sensors.

There are two scenarios in which the EDR records vehicle data: When there is a deployment event, such as when the vehicle’s airbags are deployed, or when there is a non-deployment event that meets certain criteria, such as an abrupt change in speed or direction that indicates external impact. When these thresholds are met, the EDR records input from vehicle sensors for a few seconds, capturing important information about vehicle speed, driver input, and other factors before, during, and after a crash.

While EDRs are not mandated by U.S. law, nearly every automotive OEM has voluntarily added EDRs to vehicles in recent years. According to a National Highway Traffic Safety Administration (NHTSA) document released in 2019, more than 99 percent of new cars and light trucks were equipped with EDRs as of model year 2017.

What Does the EDR Record?

For the most part, car manufacturers are free to record as much (or as little) data as they desire with their EDR units. However, there are minimum requirements for the data an EDR must record during an event.

As specified in 49 CFR part 563, EDRs must record 15 data points that are “uniform, national requirements for vehicles equipped with event data recorders (EDRs).” These mandatory data points include:

• Impact severity, as measured by the change in velocity of a vehicle (Delta-V)
• Vehicle speed
• Steering input
• Accelerator pedal input
• Brake input
• Ignition cycle
• Seat belt status
• Airbag deployment

Outside of the minimum data requirements, the information recorded by an EDR can vary greatly from vehicle to vehicle, manufacturer to manufacturer, and year to year. These variances in model-by-model data recording are likely to get more pronounced as the technical capabilities of modern vehicles continue to evolve. The emergence of in-vehicle technology such as advanced driver-assist systems (ADAS), adaptive cruise control, pedestrian detection systems, and autonomous driving systems means that current and future EDRs are likely to gather data from a larger array of in-vehicle sensors, cameras and computers.

Methods to Retrieve EDR Data

Known as EDR retrieval tools, specialized software and hardware is needed to access and download EDR data from a vehicle:

• Bosch CDR Tool – the industry standard tool. Supports over 50 brands of automobiles.
• Tesla EDR Tool – Supports all Tesla Model S, 3, X and Y vehicles
• Hyundai / Kia EDR Tool – Supports newer model Hyundai and Kia vehicles

Using the above mentioned EDR Tools, there are two methods used to retrieve the data:

• Direct Link Connector (DLC or ODB) or In-car Method
• Bench-top Method (removing the module to be downloaded)

In most cases, EDR data can be downloaded by connecting to a vehicles DLC / OBD port. This is the connector typically located beneath the dashboard of a vehicle. It is the same port used by mechanics to diagnose vehicle error codes.

For severely damaged vehicles (power has been compromised), EDR data can be downloaded by connecting directly to the module (airbag control module (ACM), rollover sensor module (ROS), and others) with a corresponding connection cable.

The retrieved EDR data is the same regardless of which method is used to download the data.

The Crash Hub EDR Expert Directory is a listing of EDR Experts that own EDR Tools and are capable of performing an EDR download and/or analyzing the report data.

Other EDR Event Data Recorder Resources

The EDR Expert Directory (The Crash Hub) is owned and operated by Crash Data Group, Inc. Crash Data Group is the North American product distributor of vehicle crash data tools and software dedicated to assisting those who investigate automobile accidents stay current with the ever-evolving and emerging automotive technologies, crash data acquisition and research studies. We also publish a bi-annual technical magazine – Collision Magazine – containing the newest crash research and articles.