Car Black Box clear driver

Jan 05, 2004 6 Replies

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According to this story, a car blackbox managed to clear a driver of accusations of reckless driving.



Just out of curiosity, since when did GM put these devices in their cars? Which model/year actually has them?


I've heard that they have them in most of their cars since they switched over to OBD-II. So around '96 and up I think.

I heard the same thing too on a Discovery channel show.

Wow, this is the first time I've heard of a EDR being used to CLEAR a driver. Normally law enforcement agencies subpoena this information with baited breath with the intent to PROVE reckless driving, and there has been much press coverage of that.

Pretty much any model with airbags. As the story implies, the EDR (event data recorder) was not originally intended to be a "black box" that investigators could use against you (or in this case, in the driver's favor). It was originally intended to give engineers some real-world data to work with to measure impact forces and crash factors, and then use that data to design better safety systems.

GM vehicles that use an SDM, which would be most later than 1996 or so, will have the vehicle data recording capability (throttle position, brake status, vehicle speed, engine RPM, and driver seat belt status for 5 seconds before either an airbag deployment or near-deployment impact). The older DERM modules had much more limited data capability - basically just recording what sensors were activated (I think) and whether any loop malfunctions were present at the time of deployment.

I am curious how tamper proof these kind of car computers are though. sounds to me like they record these things in (probably) rewritable memory. Nothing a good eprom programmer or some other exotic device programmers can not overwrite with new data. Unless they use OTP type memories. Very intriguing

Well, this page

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says thefollowing (along with other technical details): "When 150 msec have elapsed from algorithm enable, the data stored in RAM are transferred to the EEPROM. It requires about 0.7 sec to permanently record all information. Once a deployment record is written the data are frozen in EEPROM and cannot be erased, altered, or cleared by service or crash investigation personnel."

That doesn't necessarily mean that the data can't be altered by low-level access to the circuitry, unless they are using a special EEPROM chip which can be permanently write-protected, which they may well be.

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