Detroit Diesel & Mercedes
Beginning with trucks made in 1998, Detroit Diesel’s Series 60 engine came equipped with an Electronic Control Module known as the DDEC-IV. The DDEC-IV has built-in EDR capability and comes from the factory set to record event data. Before 1998, most Detroit Diesel engines were controlled by the DDEC-III, which did not store event data unless the Pro-Driver add-on was purchased and functioning.
Detroit Diesel ECMs with event data recording capability are the:
In the summer of 2000, DaimlerChrysler purchased the Detroit Diesel Corporation, and Mercedes’ MBE 4000 and 900 engines contain very similar data to the DDEC-IV and DDEC-V and are accessed with the same software and most of the same hardware. Coverage of the MBE engines began in 2002, with VCU (Vehicle Control Unit) version 12.0. The MBE 900 is common in straight-truck applications, such as ambulances, fire trucks, and local delivery trucks. New Mercedes and Detroit Diesel engines are controlled by two modules, a Motor Control Module and a Common Powertrain Controller.
The DDEC-IV, V, VI and MBE EDRs contain two types of events: a Hard Brake record and a Last Stop Record. They store the two most recent Hard Brake records and the most recent Last Stop Record. By default, Hard Brakes are recorded when the Vehicle Speed Sensor detects a reduction in wheel speed of 7mph in one second (achieving a drag factor of about 0.3g). This pre-set, 7mph/sec threshold can be changed by the end user.
The Hard Brake record reports one minute of data before the pre-set threshold was reached and 15 seconds of data after the threshold was reached.
The Last Stop Record is recorded when the wheel speed reaches 0 mph; then it is overwritten when the wheel speed reaches 1.5mph. Even driving a tractor carefully onto a flatbed wrecker will overwrite the Last Stop Record. The Last Stop Record is recorded regardless of the deceleration rate during the stop.
The Last Stop Record shows 1 minute, 44 seconds of data before the stop and 15 seconds of data after the stop. Both the Hard Brake and the Last Stop Record capture the following time-series data in one second increments:
It is important to note that the default software setting in Detroit Diesel’s DDDL software is to download and then reset the module, which erases the data. Although this makes life easier for the mechanic who wants to clear trouble codes after fixing them, erasing data can have serious ramifications for a forensic investigator.
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