Austin, T., Farrell, M., and Smith, B., "An Examination of Diagnostic Event Data in Bendix Antilock Brake System Electronic Control Units," SAE Technical Paper 2012-01-0994, 2012, doi:10.4271/2012-01-0994.
The use of Heavy Vehicle Event Data Recorders (HVEDRs) in collision analysis has been recognized in past research. Numerous publications have been presented illustrating data accuracy both in normal operating conditions as well as under emergency braking conditions [1,2,3]. To date, the bulk of this research has focused on HVEDRs incorporated into the Electronic Control Modules (ECMs) employed by various manufacturers to monitor and control engine operation. Oftentimes, data associated with engine diagnostic faults include vehicle speed and driver input parameters that are later used in a collision analysis.In addition to the ECM, other electronic control systems may store data associated with fault conditions. For example, the Antilock Braking System (ABS) Electronic Control Unit (ECU), which is tasked with electronically controlling brake application air pressure to reduce wheel lockup, is such a unit that has the ability to store diagnostic information. This study performed a detailed examination of ABS ECU diagnostic data as recorded by Bendix EC-30 and EC-60 modules. These modules were employed by actual vehicles or on training “brake boards.”It was the intent of this research to compare speed data documented in Bendix ABS diagnostic records to Global Positioning System (GPS) based information. In addition, the effect of a power loss condition on data files was examined. In total, over 50 tests were completed. Test results suggest that the use of speed data imaged from Bendix EC-60 ABS ECUs can be beneficial to crash investigators. In contrast, EC-30 controllers do not store wheel speed information. These earlier controllers can, however, assist in documenting diagnostic faults occurring at or near the time of collision.