Event Data Recorders

Engine Control Modules, Air Bag Control Modules and Crash Data Recorders

Electronic controls were introduced into small trucks and automobiles to monitor the vehicle accelerations and analyze the data to determine when an accident is occurring and whether it is serious enough to deploy the airbags. The time frame to accomplish this is very short, on the order of 25 milliseconds. These modules may continue to monitor the accelerations after the deployment of the airbag.

Passenger Vehicle Crash Data Retrieval Spreadsheet Summary  CDR

Event Data Retrieval Commercial Vehicle Summary Spreadsheet  EDT
Commercial ECM Specifics Summary Spreadsheet  ECM
PowerSpec Sample Report  Power Specs

Typical Stopping Decelerations for Hard Braking/Skidding

                                                       G’s              MPH/S

Dry Level Pavement              0.70 – 0.80       15 - 18         Automobile/Small Truck

                                              0.45 – 0.60       10 - 13         Large Truck

Wet Pavement                       0.40 – 0.60         8 - 13         Automobile/Small Truck

                                              0.40 – 0.50         8 - 11         Large Truck

Soil / Dry Grass                     0.40 – 0.50         8 - 11         All Vehicles

Rolling or Overturned            0.40 – 0.50         8 - 11         All Vehicles

Ice / Snow                              0.05 – 0.20         1 - 5           All Vehicles

Typical Low Speed Accelerations

                                                   G’s               MPH/S

Automobile/Small                  0.10 – 0.40          2 - 9

Large Truck                          0.05 – 0.15          1 - 3

Airbag Control Modules (ACM)

Electronic controls were introduced into small trucks and automobiles to monitor the vehicle accelerations and analyze the data to determine when an accident is occurring and whether it is serious enough to deploy the airbags. The time frame to accomplish this is very short, on the order of 25 milliseconds. These modules may continue to monitor the accelerations after the deployment of the airbag.

Typically record:

  • Seat belt status
  • Longitudinal collision accelerations/delta v
  • Airbag faults if present

May record:

  • Speed, RPM, throttle, braking before collision
  • Lateral collision accelerations/delta v
  • Multiple events
  • May capture data from event even if the airbags did not deploy
  • Other parameters

ACM, PCM, ROS

Audi   BMW    Chrysler    Fiat/Lancia    Ford    General Motors    Honda    Izuzu    Mazda    Mitsubishi    Nissan    Saab    Scion    Sterlling    Suzuki    Toyota    Volkswagon    Volvo

ECM - Engine Control Modules 

Caterpillar   Detroit Diesel   International   Cummins   Mack   Volvo     Mercedes Benz     Paccar (Kenworth - Peterbilt)

Electronics were introduced into the heavy truck engines to control emissions, the engine, the powertrain, and monitor the status of the primary engine operations primarily for maintenance purposes. Some of the functions such as speed, rpm, throttle and brake status are directly applicable to the analysis and reconstruction of an accident. 

Heavy truck engine manufacturers use different terminology for their particular module(s). MCM, VECU, ECU etc. all refer to the same basic components. Some manufacturers use a single module bolted to the engine. Others use two or three separate units. These can be located on the engine, frame or in the cab. Multiple units are typically split with one on the engine and the others in the cab.

Software/Hardware

  • Every manufacturer uses their own proprietary software.
  • In cab connections are standardized (6 pin or 9 pin) but may require separate hardware to access
  • Direct to ECM connections require separate cables and other hardware
  • Will provide large amounts of data on the engine and its operation.
  • May provide information on speed, RPM, braking, throttle, etc. before, during and after the collision.
  • Speed data comes from the VSS (vehicle speed sensor) that monitors the drive shaft rotation.

 Decisions to be made with respect to altering the ECM Data after an Accident

  • Should the vehicle be moved under its own power?
  • Should a download be attempted on a damaged vehicle? If so how?
  • Does downloading alter the data?
  • Can the module be removed to preserve the data?

Powertrain Control Modules

Automobiles and small trucks typically have an electronic module that controls the powertrain. These are similar in size and function to the heavy truck ECM.

Rollover Sensors (ROS)

Electronic controls were introduced into vehicles to monitor lateral accelerations for both side airbag deployment and stability control. Some of this data may be captured and available for download. Stability control is becoming increasingly prevalent in small vehicles and is beginning to appear in heavy trucks.

ROS in automobiles is accessed with the CDR system. In heavy trucks, ROS is typically associated with the stability control and is part of the braking system.

Event Data Recorders (CDR)

  • Other types of devices may provide information:
  • Vorad collision avoidance and warning
  • Wingman
  • GPS tracking
  • ABS brake systems
  • PeopleNet
  • QualComm
  • EasyPass
  • Electronic Logbook
  • VORAD (Vehicle Onboard Radar)

Vorad Collision Avoidance and Warning (VORAD)

VORAD was Developed and implemented by Eaton, and is now owned by Bendix. It was introduced in 1992. Download information has been available since 1995. It provides early warning to drivers (lights/sounds) of vehicles evaluated as hazards either by proximity or closure rate. Downloads are a commercial service provided by the manufacturer 

ECM Download

ECM - Engine Control Module

ECM - Truck Download

Truck Download