The Controller Area Network (CAN) is a complex automotive bus network that interconnects various devices without a central computer. Between the devices, there’s an exchange of data and working parameters, which are loaded with information about the messages to be exchanged via the serial data circuits.
There are two specific wires to carry out the communication for the CAN bus (CAN high and CAN low). At idle, the CAN bus lines have 2.5 volts. In bit communication, the high CAN carries 3.75, while the low one carries 1.25 volts. This way, they maintain a differential of 2.5 between both lines.
To send information via both CAN buses, it is executed through the Totally Integrated Power Module (TIMP). Utilizing codes, the TIMP identifies which module is sending information. This transmission of information is called binary conversation.
The diagnostic code U0003 OBDII is stored when a problem is detected on the high-speed CAN communication bus due to an open circuit. OBDII Fault Codes correspond to the U-Codes (Network Communications) also known as network communications codes. This fault code applies to all communication components of the vehicle’s electronic system.
Automobiles that have an Electronic Control Module (ECM), which serves as the brain of the vehicle, are responsible for sending and receiving information from all the electronic modules of the automobile. So a U-Codes type failure symbolizes a deficiency somewhere in the ECM.