The U1101 OBDII diagnostic code is a manufacturer-specific code that is stored when the PCM (Powertrain Control Module) loses communication with the primary control module for a determined system. In most cases, this code points to the TCM (Transmission Control Module).
The SCP stands for Standard Corporate Protocol, which is a communication protocol used by several vehicle manufacturers. The J1850 is the SAE standard that describes the SCP protocol. When a vehicle operates, the control modules communicate with each other via the Controller Area Network (CAN). When sending data, each module sends its unique identification code along with the information it sends. The identification code shows the source of the data transmission.