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These are some frequent questions on motor vehicle Event Data Recorders (EDR).
The technology is changing rapidly and these answers may not apply to every
situation.
Please see the list of service providers if you wish to contact
someone capable of recovering and downloading an EDR.
1. What cars are equipped with an EDR?
A complete and current list of all GM and Ford vehicles
with an EDR that can be downloaded using the Vetronix Collision Data Recovery
(CDR) Tool is provided HERE.
Other automakers, may have some form of a data
recorder on board. Until these automakers release the software and hardware
required, these recorders can only be downloaded by the manufacturer.
2. Can I disable or remove the EDR from my car before a
crash?
The EDR is an integral component of the vehicle's
occupant crash protection systems required by the Federal Motor Vehicle
Safety Standards. The removal or disconnection of the module which houses the EDR will disable the air bags
and possibly other safety components.
It is a violation of federal law for a repair facility to deactivate the air bag system:
United States Code
Title 49 Transportation
Chapter 301 Motor Vehicle Safety
Subchapter II Standards and Compliance
Section 30122 Making Safety Devices and Elements Inoperative
a. Definition - In this section, "motor vehicle repair business" means a
person holding itself [sic] out to the public to repair for compensation a motor
vehicle or motor vehicle equipment.
b. Prohibition - A manufacturer, distributor, dealer, or motor vehicle repair
business may not knowingly make inoperative any part of a device or element of
design installed on or in a motor vehicle or motor vehicle equipment in
compliance with an applicable motor vehicle safety standard prescribed under
this chapter unless the manufacturer, distributor, dealer, or repair business
reasonably believes the vehicle or equipment will not be used (except for
testing or a similar purpose during maintenance or repair) when the device or
element is inoperative.
c. Regulations - The Secretary of Transportation may prescribe regulations to
exempt a person from this section if the Secretary decides the exemption is
consistent with motor vehicle safety and section 30101 of this title; and to
define "make inoperative". (Note this last section applies to the
installation of air bag ON/OFF switches in certain vehicles with written
authorization from NHTSA. This will not disable the EDR.)
3. Can I remove the EDR after a crash?
This could result in questions due to custody
of evidence issues at a later date. Each EDR module has a serial number that can be
traced to a specific vehicle. The removal of an EDR module should
only be performed by a qualified technician.
4. Can
I remove the EDR after a crash and send it to you to download the data?
This is not recommended.
There is a possibility of data corruption if certain
safeguards are not taken
when the module is disconnected from the vehicle. This
action could also result
in chain of custody issues at a later date. With the
current technology,
downloaded EDR information may not stand alone as
evidence; it must be
analyzed in conjunction with other evidence from the crash.
The removal of an EDR should only be performed by a qualified technician.
5. How is the data stored in the module?
Crash data is written to an EEPROM chip in the module.
It is this information that is retrieved with the CDR Tool.
6. Can I replace the module following a crash with
another one?
Yes. The air bag control module, which houses the EDR, is
replaced if the air bag system is repaired. Air bag repair and
replacement must be accomplished by a qualified repair technician.
7. Where is the EDR module located in my car?
EDR modules are in various places. They are not specifically marked as
EDR modules.
8. Can the police issue a speeding ticket based on the
data within the module? Could they just plug something into my car to see if I
was speeding?
No. The EDR only records data following an air bag deployment,
deployment level or near deployment event. Being pulled over for speeding will not result in data
being recorded and there would be nothing to download.
9. Can the EDR record where my car was, or how fast I
was going last night?
No. The EDR only records a brief
time period preceding a crash. In most circumstances, it can record up to five
seconds before a crash. It does not record time, date, location, who was
driving, steering inputs, conversations or outside conditions. Recorded data
is generally limited to vehicle wheel speed, brake application, air bag status,
driver seat belt status, engine RPMs and collision force data. Some models of EDRs do not record any pre-crash data, only
collision data.
10. Who can gain access to this EDR data?
Anyone with the proper equipment and
software. Legal issues have not been addressed by the
courts.
11. Is data always recorded in the event of a crash?
No. The EDR is designed to record data in the event of an
air bag deployment, deployment level or near deployment event. Rear-end and oblique crashes
may not result in any data being recorded. A catastrophic loss of vehicle
power during to the crash event may also result in no data, or incomplete
data, being recorded as the unit has limited internal power reserves.
12. What do all these acronyms stand for?
DERM - Diagnostic and Energy Reserve
Module. Introduced by GM in some production cars beginning in 1990, this is
the predecessor to the current SDM.
Crash Data Retrieval CDR Tool - The registered trademark
name of the hardware interface and software sold by Vetronix, Corp., to
download EDR data.
EDR - Event Data Recorder. This term is
used by NHTSA and the SAE. Also see MVEDR and CDR.
CDR - Collision Data Recorder. A shortened
term for Collision Data Recorder (CDR) Tool. Sometimes used as crash data
recorder or collision data recorder in a generic sense.
MVEDR - Motor Vehicle Event Data Recorder.
A term coined by the Institute of Electrical and Electronics Engineers, Inc.
(IEEE). Through its technical publishing and consensus-based standards
activities, the IEEE publishes standards for electronics. Also see EDR and
CDR.
SDM - Sensing & Diagnostic Module.
Beginning with the 1994 model year, GM replaced the multiple electromechanical
switches previously used for crash sensing (DERM) by the combination of a
single, solid state, analog accelerometer and a computer algorithm integrated in
a single module.
OBD - On Board Diagnostics.
OBD II or OBDII - Updated On-Board
Diagnostics standard effective in cars sold in the U.S. after January 1, 1996.
DLC - Data Link Connector. This is the
connection in the passenger compartment to which the CDR Tool can be connected
to download data without direct access to the EDR.
ECM - Engine Control Module. The main
on-board computer controlling emissions and engine operation.
ECU -
Engine Control Unit. Basically the same as ECM, sometimes used
interchangeably. The ECUs in some large trucks also record data that can be
downloaded with manufacturer provided equipment.
VCM - Vehicle Control Module. The on-board
computer that oversees engine management, transmission operation, anti-lock
brakes and other functions not directly related to emissions control.
DTC - Diagnostic Trouble Code. This is the
display provided by the scan tools used by mechanics to isolate trouble codes
through the DLC.
PCM - Powertrain Control Module. The
on-board computer that controls engine and drive train.
BCM - Body Control Module. The on-board
computer that controls interior lights, settings and other aspects not
controlled by the PCM or ECM.
RCM - Restraint Control Module (Ford). The occupant restraint control module,
activates the air bags and other restraint components in the event of a
crash..
