Citation

Reust T, Morgan J, Ruth R. Collision 2008; 3(1): 48-51, 58-59.

Copyright

(Copyright © 2008, Collision Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Data from event data recorders can be useful in accident reconstruction. This paper reports on tests that were conducted with instrumented vehicles to enable a comparison of a calibrated speed to the Ford powertrain control module (PCM) recorded speed. The PCM-reported speed data is generated from the vehicle speed sensor and reports the speed proportional to the rotation of the vehicle's drive wheels. The tests provide information on the accuracy of the speed during normal operating conditions, heavy acceleration, cornering, maximum brake application and during critical speed yaw events. Findings show that the accuracy of the PCM-reported speed during low and maximum acceleration and during steady speeds is approximately ±0.8 mph. During maximum brake application of a vehicle with an antilock braking system, the PCM-reported speed was underreported by approximately 0.5 to 14.3% at PCM-reported speeds of 20 mph and higher. When a vehicle is in a critical speed yaw, the PCM-reported speed was underreported by approximately 0.02 to 2.9% when only steering was used and was underreported by approximately 0.11 to 5.2% when both steering and braking were used. For one data sample the speed was overreported by approximately 1.25 mph during maximum acceleration when a gear shift took place with an automatic transmission.