Truck EDR (Black Box) Download and Analysis


The Engine Control Module (ECM) is found in almost all modern heavy trucks. Data from the ECM is collected and stored in the event data recorder (EDR). Downloading data from the truck’s EDR can provide the accident reconstructionist with information related to the vehicle’s speed, braking, clutch and throttle position, etc. prior to a crash. However, it is important to understand that the purpose of an ECM is to control engine performance, emissions systems, fuel use, etc. It is designed to take “snapshot” data under various scenarios related to the truck’s operation, not record crash data.

Heavy truck ECMs contain four types of data:

  • fault data
  • historical data
  • calibration data
  • event data

Each category of data provides different information that can be useful in driver monitoring, vehicle maintenance and repair, and crash investigation. Data recording by each manufacturer’s ECM does not follow a standard protocol and the amount of data generated can vary substantially between manufacturers.

Unlike an airbag control module, the event data recorder in an ECM is not triggered by a crash.  Therefore, the analysis and interpretation of the downloaded data from an ECM requires the knowledge and experience to discern which of the numerous reports generated contain information that is related to the crash.

Crash Response has the hardware and software required to download EDR data from most engine manufacturers.  Mr. Owen has the experience, knowledge and training to accurately interpret and analyze the ECM data.

Further reading

Differences Between a Passenger Vehicle and Heavy Truck Event Data Recorder (EDR)
In a passenger car or light truck / SUV, the EDR is contained within the Air Bag Control Module (ACM). Any data retrieved from this module is related to a sudden deceleration most likely caused by a crash. Therefore, the data usually relates to the crash event in question.

The EDR for a heavy vehicle such as a truck tractor is contained within the Engine Control Module (ECM) and is designed to take “snapshot” data under various scenarios relating to the truck’s operation. The ECM controls engine performance, emissions systems, fuel use, driver incentives, etc. and records data useful for safety management, etc. Its purpose is not designed to record “crash data”, but many times the “snapshot data” also relates to the crash event in question. The ECM “snapshot” is not triggered by a crash event like the Air Bag Control Module is.

As an example, “quick stop” events are used by the trucking company to judge a driver’s behavior behind the wheel. If a driver performs an excessive number of “quick stops”, the driver may not using good defensive driving techniques and may also be abusing the trucking company’s equipment. However, a “quick stop” event may also occur just prior to a collision and then this data can be valuable to a reconstructionist.

In summary, EDR data from an Air Bag Control Module usually relates to a crash event. The EDR data from an Engine Control Module may relate to a crash event.