Serial Data Reference

The scan tool communicates over the various buses on the vehicle. When a scan tool is installed on a vehicle, the scan tool will try to communicate with every control module that could be optioned into the vehicle. If an option is not installed on the vehicle, the scan tool will display No Comm for that optional control module. In order to avert misdiagnoses of No Communication with a specific control module, refer to Data Link References  for a list of control modules, the buses they communicate with, and the RPO codes for a specific control module.