CDR is Crash Data Recovery. CDR means downloading the data or “image” collection from a vehicle’s EDR. A certified technician should do this process.

EDR is the Event Data Recorder. EDR refers to a device installed in a motor vehicle to record technical vehicle and occupant information briefly before, during, and after a crash. The EDR recording is measured in a few seconds in most vehicles. However, depending on the manufacturer, it can record up to a few minutes. These recordings can recreate the chain of events leading up to a crash.

EDRs are devices that record information about an “event.” An event is defined as a vehicle crash. For instance, EDRs may record the following:

1. Pre-crash vehicle dynamics and system status
2. Driver inputs
3. Delta V (the change in velocity between pre-collision and post-collision trajectories of a vehicle)
4. Vehicle restraint usage/deployment status
5. Post-crash data, such as the activation of an automatic collision notification (ACN) system

Popularly known as “black boxes,” event data recorders (EDRs) have helped investigators solve the mysteries of airplane crashes for decades. Now they’ve become standard in almost every new car sold.

General Motors first introduced EDRs in a basic form on air-bag-equipped models in the mid-1970s; EDRs were being used by various manufacturers in 64 percent of all new models by the 2005 model year, according to the National Highway Traffic Safety Administration (NHTSA). Likewise, the Insurance Institute for Highway Safety (IIHS) says more recent data shows that all new cars have some form of EDR. But the specific information gathered varies by the auto manufacturer, and some companies make it easier to retrieve data than others.

Despite their presence in cars since the mid-1990s, they have not fulfilled their potential because automakers collect different data and use dissimilar systems to retrieve it. Now that will change, following a rule by the National Highway Traffic Safety Administration (NHTSA) that took effect September 1, 2012.
The rule standardizes the data collected by the black boxes and how the technicians can retrieve the data.

A new NHTSA proposed rule would require these EDRs in all light-passenger vehicles, starting September 1, 2014. NHTSA estimates that approximately 96 percent of the model year 2013 passenger cars and light-duty vehicles are already equipped with EDR capability.

The significance of this measure is in the specifics of what data it requires such devices to collect and its guidelines for how the data should be accessed.
The data must include the following:

• The forward and lateral crash force.
• The crash event duration.
• Indicated vehicle speed.
• Accelerator position.
• Engine rpm.
• Brake application and antilock brake activation.
• Steering wheel angle.
• Stability control engagement.
• Vehicle roll angle, in case of a rollover.
• The number of times the vehicle has been started.
• Driver and front-passenger safety belt engagement and pre-tensioner or force limiter engagement.
• Airbag deployment, speed, and faults for all airbags.
• Front seat positions.
• Occupant size.
• The number of crashes (one or more impacts during the final crash event).