Event Data Recorder Bypass
For starters, I see two possible solutions. One would be to replace the module with a non-recording module that would still allow the airbags to function. Another would be to have an "Interceptor" similar to some electronic fuel injection module add ons. This would possibly change some or all of the paramaters using an algorithm.
Please chime in for other solutions. Hopefully someone here might know how to build a prototype or at least get us pointed in the right direction. Evidently, the modules are no longer encrypted and will soon have standardized formats across car makes.
Last edited by 2KFRC5; Nov 27, 2006 at 12:01 AM.





Ok, does anyone know if the ABS will work when the module is removed and replaced with a simple jumper cable?
The Best of Corvette for Corvette Enthusiasts
Ok, does anyone know if the ABS will work when the module is removed and replaced with a simple jumper cable?
Just a thought but if you were to make and install such a simulator and get yourself into a situation where the EDR could save or lock you up and in its place they find the simulator which has only one purpose (cause it aint for performance), dont you think that would make you look guilty? I'm sure it would not help your cause.
The reason it is all over the news is that people don't like this intrusion into their life, even with spotless driving records (such as mine). The data recorder is not open to inspection, debate, or independent confirmation at anytime after it has been installed. Is there any data on accuracy or malfuntions. Please don't tell me that there aren't any. I would find that very hard to believe.
I was hoping that people be interested in the intellectual challenge of reversing this. If not I wonder how many people would be willing to remove the data recording function by whatever means assuming it is completely legal. Maybe we should take a poll?
If it helps to understand, the SDM is BOTH a black box (or EDR as you call it) and the device that controls the entire Airbag system.
The SDM isn't a "dumb" device, it is a microprocessor with memory (which is where the 5 seconds of data, plus lots of other stuff is also stored) and also systems such as a 23 Volt Loop Reserve (VLR) that is used to provide the electrical power to detonate the air bags should battery voltage be lost during the crash event and an accelerometer to measure vehicle speed changes. The SDM is wired into various vehicle systems, and as part of its on-going internal diagnostics checks to be sure it is receiving the following data .....
Quoted from the Vetronix website:
http://www.vetronix.com/aftermarket/
======================================== ==========
Q: Where does the air bag module (SDM) collect its data?
A: All SDM recorded data is measured, calculated, and stored internally, except for the following:
Vehicle Speed, Engine Speed, and Percent Throttle data is transmitted once a second by the Powertrain Control Module (PCM) via the Class 2 data link, to the SDM.
Brake Switch Circuit Status data is transmitted, once a second by either the ABS module or the PCM via the Class 2 data link, to the SDM.
Depending on vehicle option content, the Brake Switch Circuit Status data may not be available.
In most cases, the Driver's Belt Switch Circuit is wired directly to the SDM.
In some vehicles, the Driver's Belt Switch Circuit Status data is transmitted from the Body Control Module (BCM), via the Class 2 data link, to the SDM.
The Passenger Front Air Bag Suppression Switch Circuit is wired directly to the SDM.
======================================== ===========
If this data isn't available to the SDM, it throws a DTC, turns on the AirBag light, and ... well .... you have no airbags.
So, to build a bypass all you need to do is find an appropriate microprocessor, write all the appropriate software for diagnosing the entire restraint system, figure out the interface to the Class 2 data bus (so you can at least turn on/off the Airbag light in the instrument panel and respond to health checks from the PCM) ... write the algorithms to decide when to fire or not fire the bags ... oh and put that VLR circuitry and accelerometer in there too.
Let me know when you've completed this little task ... probably only took GM a couple of years and a couple of dozen hardware/software engineers to do this ....
Last edited by BlackZ06; Nov 27, 2006 at 11:04 PM.
Any other ideas?
If it helps to understand, the SDM is BOTH a black box (or EDR as you call it) and the device that controls the entire Airbag system.
The SDM isn't a "dumb" device, it is a microprocessor with memory (which is where the 5 seconds of data, plus lots of other stuff is also stored) and also systems such as a 23 Volt Loop Reserve (VLR) that is used to provide the electrical power to detonate the air bags should battery voltage be lost during the crash event and an accelerometer to measure vehicle speed changes. The SDM is wired into various vehicle systems, and as part of its on-going internal diagnostics checks to be sure it is receiving the following data .....
Quoted from the Vetronix website:
http://www.vetronix.com/aftermarket/
======================================== ==========
Q: Where does the air bag module (SDM) collect its data?
A: All SDM recorded data is measured, calculated, and stored internally, except for the following:
Vehicle Speed, Engine Speed, and Percent Throttle data is transmitted once a second by the Powertrain Control Module (PCM) via the Class 2 data link, to the SDM.
Brake Switch Circuit Status data is transmitted, once a second by either the ABS module or the PCM via the Class 2 data link, to the SDM.
Depending on vehicle option content, the Brake Switch Circuit Status data may not be available.
In most cases, the Driver's Belt Switch Circuit is wired directly to the SDM.
In some vehicles, the Driver's Belt Switch Circuit Status data is transmitted from the Body Control Module (BCM), via the Class 2 data link, to the SDM.
The Passenger Front Air Bag Suppression Switch Circuit is wired directly to the SDM.
======================================== ===========
If this data isn't available to the SDM, it throws a DTC, turns on the AirBag light, and ... well .... you have no airbags.
So, to build a bypass all you need to do is find an appropriate microprocessor, write all the appropriate software for diagnosing the entire restraint system, figure out the interface to the Class 2 data bus (so you can at least turn on/off the Airbag light in the instrument panel and respond to health checks from the PCM) ... write the algorithms to decide when to fire or not fire the bags ... oh and put that VLR circuitry and accelerometer in there too.
Let me know when you've completed this little task ... probably only took GM a couple of years and a couple of dozen hardware/software engineers to do this ....



Any other ideas?
I just happen to design airbag modules (Not for Delphi - Probably the
manufacturer of your SDM) and have a couple of comments:
1) Don't be so sure that it is an external EEPROM IC
2) EEPROM is used for more than event recording. It typically holds
calibration info, etc which is needed to make the module function
3) Simply removing an IC WILL be detectable and would be considered internal
fault and make the module non-operational
I would buy another module and have it ready to be swapped out if needed.
However, this is not fool proof...
Having a functional module is worth the risks.













