System Description

BRIEF DESCRIPTION
1. The CAN (Controller Area Network) is a serial data communication system for real time application. It is a vehicle multiplex communication system which has a high communication speed (500 kbps) and the ability to detect malfunctions.
2. By pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltage.
3. Many ECUs (sensors) installed on the vehicle operate by sharing information and communicating with each other.
4. The CAN has two resistors of 120 Ω which are necessary to communicate with the main bus line.
DEFINITION OF TERMS
1. Main bus line
  1. The main bus line is a wire harness between the two terminus circuits on the bus (communication line). This is the main bus in the CAN communication system.
2. Sub bus line
  1. The sub bus line is a wire harness which diverges from the main bus line to an ECU or sensor.
3. Terminus circuit
  1. The terminus circuit is a circuit which is placed to convert communication current of the CAN communication into bus voltage. It consists of a resistor and condenser. Two terminus circuits are necessary on a bus.
ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM
1. Skid Control ECU
2. Yaw Rate Sensor
3. Steering Angle Sensor
4. ECM
5. Network Gateway ECU
6. Navigation ECU*1
  *1: w/ Navigation system
DIAGNOSTIC CODE FOR CAN COMMUNICATION SYSTEM
1. DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0123, U0124, U0126 and U0132.
  NOTE:
  U0001 are displayed on the Techstream "Communication Malfunction DTC". Refer to DIAGNOSIS SYSTEM screen, but they are not DTCs in the CAN communication system. Refer to the appropriate troubleshooting article of each system.
REMARK FOR TROUBLESHOOTING
1. Trouble in the CAN bus (communication line) can be checked from the DLC3 (except when there is a wire break other than in the sub bus line of the DLC3).
  NOTE:
  Do not insert the tester probes directly into the DLC3 connector. Be sure to use service wires.
2. DTCs regarding the CAN communication system can be checked using the Techstream.
3. The CAN communication system cannot detect trouble in the sub bus line of the DLC3 even though the DLC3 is also connected to the CAN communication system.