Finding the black box in your car
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In the United States, there are approximately 190 million drivers. If you are driving a car manufactured by GM or Saturn, you could be carrying around an event data recorder (EDR) and not even know it. The EDR senses various conditions in and around the vehicle and that can then be obtained by various individuals for various purposes.
EDRs record the following data:
Vehicle speed (five seconds before impact)
Engine speed (five seconds before impact)
Brake status (five seconds before impact)
Throttle position (five seconds before impact)
State of driver's seat belt switch (On/Off)
Passenger's airbag (On/Off)
IR Warning Lamp status (On/Off)
Time from vehicle impact to airbag deployment
Ignition cycle count at event time
Ignition cycle count at investigation
Maximum velocity for near-deployment event
Velocity vs. time for frontal airbag deployment event
Time from vehicle impact to time of maximum velocity
Time between near-deploy and deploy event (if within five seconds)
Using this data, insurance agents and police officers can reconstruct the events leading up to a crash. Black boxes have been in all GM cars since 1999 and in many other makes and models since 1996. (See below to see if your car comes standard with one.)
EDRs were originally intended to record what caused air bags to open. The data that triggers the air bag often tells the story of what happened in the seconds before a crash.