BMW Z4 converted race car with extensive modifications was purchased by a customer from a US private team seller with no build documentation. Vehicle had history of extensive electrical problems resulting in multiple Did Not Finish (DNF) and eventual on-track accident.
Due to the lack of build documentation compounded by the additional repairs completed from the on-track accident (rebuilt prior to purchase by customer), many significant challenges had to be overcome to rectify the electrical and mechanical deficiencies.
Diagnostics included use of general purpose OBD scan tools (iScan), BMW dealer level scan tools (ISTA), and low-level signal monitoring (digital oscilloscope). Extensive repair and modifications to all electrical systems were required to rectify the failure condition root-cause, identified as engine (ECU) immobilization due to both high-speed CAN-BUS faults, secondary diagnostic bus (D-BUS) faults, and tertiary direct-link module communication faults (EWS to ECU link).
Ultimately it was determined the vehicle was improperly modified during the build process which lead to D-BUS failure and the no-start condition due to immobilization. This was further compounded by: modification attempting to rectify the original issue, as well as damage to the wiring harness suffered during the accident and improperly repaired. Vehicle was successfully repaired and able to provide many hours of reliable on-track use for the customer.