“Can’t Touch This!” - The Difference Between ACMs & EDRs

After airbags became optional in vehicles, there became a natural need for manufacturers to know what was occurring during an airbag deployment. They wanted to know if their sensors were performing correctly and if the algorithms could be enhanced--assessing the overall dependability of the airbag deployment and ultimately for product liability issues. Some manufactures began to include black boxes as standard equipment almost 45 years ago[1].

Even though the term “black box” is not technically sound, it is what many people quickly identify as a type of catastrophic event recorder or Event Data Recorder (EDR). An EDR is the device accessed to image the crash data in a personal passenger automobile. The term “image” is synonymous with making a copy of; this term is used to avoid misinterpretation of what is occurring.

The imaging process itself cannot change, alter, or manipulate the data in any way--no matter who images it--as long as proper protocols are followed. In certain situations data can be erased or added to the EDR. The most common evidence spoliation scenarios are with specific early model Airbag Control Modules (ACMs).

Although this risk exists, by 2016, the data has been accepted in over 100 admissibility hearings--two of which occurred in cases being heard by the US Supreme Court[2]. It has never failed an admissibility hearing due to the validity of the data itself[3].

Furthermore, the EDR is an electronic function within the ACM. Think of it as a calculator. The ACM we can touch, the EDR we cannot. With access to the ACM, we can use our tools to access the information recorded by the EDR after an event.

We use the Bosch Crash Data Retrieval Tool, which is estimated to be supported by over 156 million registered vehicles in the United States alone[4]. Additionally, we are capable of serving the North American Market.

Even if the data is not commercially available through our tools, it is possible to request the information from the manufacturer. However, you will be subject to their protocols for acceptance and processing.


[1] Event Data Recorders: A Decade of Innovation, SAE-PT139, ISBN-978-0-7680-2066-3, Pg.11

[2] http://www.crashdatagroup.com/learnmore/BlackBoxMyths_Haight.pdf

[3] http://www.ruthconsulting.com/docs/Sept-2010/Davis%20&%20Young%20legal%20update%20EDR%20presentation%20April%202010.pdf

[4] http://www.ruthconsulting.com/docs/2017_May/EDR%20Update%2017.3%20May%2022%202017.pdf


David AtkinsonComment