Technical Service Bulletin A451510 2042048- — 1999 AUDI A6

Vehicle will not communicate with diagnostic scan tool or emissions test equipment. Customers may have issues with vehicle passing state IM emissions test programs because the scan tool cannot communicate with the vehicle. ABS and/or brake lamp(s) will be illuminated in IP cluster. Broken ground bond wire within the ABS module (ABS 5.3 system) causes diagnostic communication issues with the ABS module, ECM, and TCM. Brake system and ABS system functionality are not affected by the broken ground circuit. This bulletin only addresses the communication issue (broken ground circuit) between the vehicle and the diagnostic scan tool described above. This bulletin does not address any subsequent vehicle diagnostic system issues that may exist. OBD system works normally; emission or diagnostic critical malfunctions will be indicated by MIL illumination. ABS system is not functionally affected by the broken ground circuit.