SERVICE INFORMATION Related to communication codes U1000, U1001, U1002, U1010: - Always diagnose the communication codes first. - When a module reports a U1000 code, it is typically operating normally; however, there is a communication error external to that module on the CAN network. - U1000 indicates an error. V-CAN diagram or CAN Diag Support Monitor provides data to determine the location of the error. See this bulletin for more information.