At Veritech, we perform a lot of accident reconstructions that start with black box data downloads from vehicles. We’ve covered black box downloads in other blog posts. These downloads capture pre-impact, impact, and post-impact data that are related to a crash. The information gathered during a download can be valuable as a starting point when performing an accident reconstruction. After all, having information relating to the vehicle’s speed and pre-impact behavior is often important when coming up with answers relating to a car accident. Most commonly, the vehicle’s airbag control module or “ACM” is the electronic piece of equipment that does the data logging during an accident. The ACM is what decides on deployment of the vehicle’s supplemental restraint system, or airbags. In some accident scenarios, the ACM may determine that airbag deployment is not necessary. So, if your accident does not have airbag deployment, does this mean that there is no impact-related data recorded by the ACM? This is a question that we get a lot from attorneys, adjusters, and even curious and inquisitive citizens who call us. The answer is complicated because in most cases, there will be data, but not always. This is because of a couple of reasons:
Reason 1: The impact did not “wake up” the ACM. In many minor collisions, the ACM will not be aware that an impact took place. This is because most ACM’s are not programmed to even record data below a certain threshold. This threshold is commonly 5 mph. In other words, an impact that produces a change in speed of less than 5 mph will not record data. Some ACM’s are different than others, however, and could have a different threshold than 5 mph. An interesting side note: most vehicle bumper systems that conform to FMVSS 581 are designed in such a way to withstand a 5 mph impact in most cases.
This screenshot shows that an event was recorded by the ACM, but it was a "Non-Deployment" event. In other words, the airbags did not fire as a result of the crash.
Reason 2: The ACM is too old. Some early versions of ACM’s do not store any data without deployment. For example, many older Ford models (2000’s model years) may have some sort of recording capability, but could not be able to record data in certain impact related events.
Reason 3: The impact was not head-on. Some accident scenarios will produce a 5 mph impact delta-v, however since the impact was not head-on, some component of the impact delta-v may be associated with a side impact. Therefore, since the crash pulse in split between front and side, and may not be sufficient to record any data.
The graph above shows a relatively high delta-v for a non-deployment event. While the delta-v (crash pulse) was higher than 5 mph, it still was under the threshold of deploying the airbags during the crash. This decision was made by the ACM during the crash.
There may or may not be data associated with your crash. The circumstances surrounding the impact and whether or not your specific vehicle are capable of recording data must be taken into consideration when deciding on whether or not to pursue a black box download. The first step, as always, is to contact us. We can help guide you through the process and look up the details of your specific vehicle in our extensive database. Thanks for reading, and Happy Friday!