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Extraction and Analysis of Data from Commercial Vehicle ECMs Boster, Kobayashi & Associates has acquired the hardware and software to extract and analyze Event Data Recorder (EDR) data on Detroit Diesel Corporation (DDC) Series 60 diesel engines, Mercedes-Benz MBE-900 and MBE-4000 series engines. These engines are in widespread use in the medium and heavy-duty truck market, including trucks and truck-tractors manufactured by Mack, International, Freightliner, Western Star, Sterling and others. In addition, DDC engines are offered as standard or optional equipment by virtually every bus and coach manufacturer in North America. Vocational trucks, fire trucks, and luxury motorhomes also utilize these engines. The Engine Control Modules (ECMs) in use on the more recent versions of these engines (1998 and later) quite often contain data that is valuable in the analysis and reconstruction of motor vehicle accidents. |
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Detroit Diesel Corporation is a leading manufacturer of electronically controlled diesel engines for the commercial vehicle market. DDC Series 60 engines have been the #1 selling heavy-duty engine for 12 years in a row. These engines are equipped with Detroit Diesel Electronic Controls (DDEC). DDEC’s primary functions relate to optimizing engine performance, efficiency, and emissions. It also captures and stores data used to produce a wide range of diagnostic and management reports. Beginning in late 1997, the fourth generation DDEC systems (known as DDEC IV) included the ability to record data related to hard brake and last stop events. DDEC V, introduced in late 2003, provides similar data recording features. |
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The DDEC software, Detroit Diesel Diagnostic Link (DDDL) and DDEC Reports, is used in conjunction with a translator box and laptop PC to download data from the ECM. If the vehicle electrical system is intact post-accident, the download is accomplished by plugging into the diagnostic link connector in the cab of the truck. If the vehicle is so badly damaged that download through the diagnostic link connector is not feasible, download directly from the ECM is usually possible. The DDDL and DDEC Reports software package produces a wide range of diagnostic and management reports. A download from a DDEC IV/V Electronic Control Module (ECM) may contain a trip activity report, monthly activity reports (3 months), vehicle speed/engine load/rpm data, diagnostic records, hard brake reports (last two hard braking events), a last stop record, and a daily engine usage report (30 days). The reports most useful in accident reconstruction are typically the Hard Brake Report and/or the Last Stop Record. A Hard Brake Report is the historical detail of the vehicles last two hard braking events (Hard Brake #1 and Hard Brake #2). A Hard Brake Report is triggered when the calculated vehicle speed decreases by a user defined threshold. The default value is 7 mph per second, which means that if the vehicle slows 7 mph or more in 1 second, a Hard Brake Report will be generated. This corresponds to a deceleration rate of approximately 0.32 g’s. The Hard Brake Report contains vehicle and engine operating data for 1 minute and 15 seconds before and 15 seconds after the trigger point. Data is captured in 1 second intervals, and includes the data shown in Table 1.
Vehicle speed, brake and clutch status, throttle position and cruise control status are particularly relevant in the reconstruction of an accident. Hard Brake Reports also display the time and date of occurrence. The Last Stop Record is also useful in accident reconstruction. A Last Stop Record is triggered when the vehicle speed changes from the drive state (greater or equal to 1.5 mph and engine RPM greater than zero for two seconds) to the stop state (less than 1.5 mph or ignition turned off) and subsequently remains stopped for 15 seconds. The Last Stop Record contains the same data shown in Table 1, but for an even greater period of time. The Last Stop Record contains vehicle and engine data (in 1 second intervals) for 1 minute and 45 seconds before and 15 seconds after the last stop trigger point. Ideally, data extraction should occur immediately following an accident and before the vehicle is restarted or moved. This is not always possible, however, for the obvious reasons. As long as the vehicle has not been driven post-accident, the data will be preserved in the ECM. Even if the vehicle is driven (and the Last Stop Record overwritten with a new one), data may still be available from the Hard Brake Reports if the vehicle has not been subjected to two additional hard brake events. Subsequent hard brake events are recorded over the existing Hard Brake Reports, and once overwritten, the data is gone forever. Thomas Braun has attended the Detroit Diesel Training Center and completed a course of instruction on DDEC Reports/Data Extraction. Boster, Kobayashi & Associates is now on DDC’s list of DDEC Data Extraction and Analysis Providers.
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Reprinted from The Reconstructor, Newsletter of Boster, Kobayashi & Associates, Summer 2005. |
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