Citation

Smith B, Messerschmidt W, Demonia R. Collision 2009; 4(2): 74-80.

Copyright

(Copyright © 2009, Collision Publishing)

DOI

unavailable

PMID

unavailable

Abstract

It is often challenging for accident reconstructionists using imaged electronic control module data to link event records to a specific incident. Issues such as clock drift, improper programming and power failures can create uncertainty about how (and if) the captured event data relate to the incident being investigated. This paper describes testing that was done to examine the creation of a new last stop record under circumstances that were outside the routine use of the Mercedes-Benz diesel engine MBE 4000. A total of 18 test runs were performed, each focusing on different scenarios that were meant to address fundamental questions about the way MBE electronic controls record and store data. Three types of tests were conducted to determine how an existing last stop record is overwritten by a new last stop record, the impact of multiple ignition cycles on the last stop record, and the effects of simulating a power failure by cycling the key switch to off while the vehicle was in motion. Findings indicate that the MBE 4000 generates a last stop record when the key switch is cycled to off, regardless of whether the vehicle is stopped, or wheel speed is measured to be 0 mph, provided that the vehicle has been in motion during that key cycle. If the ignition cycle lasts less than 1 minute, 44 seconds, values of zero and off function as placeholders in the incomplete report. When the vehicle was turned off while still in motion, a new last stop record was created. These findings indicate why many collision events fail to set a last stop record. Limitations of this study are discussed.