Numerous codes on 2003 XC70--new ECM??
 

ECM-928C, EOOO, 510F, 9400, 4050, 400C
SRS-0004, E003
Display reports brake failure, others
Add'l diagnostics fail w/ message "Fault in communication with ECU."
Suggestions?

the speed sensors connect to the ABS and Tranmission computer and to the ECU. I'd look into the symptoms of a failed ABS controller board. Not sure about your model year but its a common fault area for 2000 vintage Volvos where the solder joints in the ABS board crack and cause errors and codes.
Google Midwest ABS and RochaTek for details.

Thanks! I'll look into this.