Can Communication System -- System Description |
BRIEF DESCRIPTION |
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.
By pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltage.
Many ECUs (sensors) installed on the vehicle operate by sharing information and communicating with each other.
The CAN has two resistors of 120 Ω which are necessary to communicate with the main bus line .
DEFINITION OF TERMS |
Main bus line
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.
Sub bus line
The sub bus line is a wire harness which diverges from the main bus line to an ECU or sensor.
Terminus circuit
The terminus circuit is a circuit which is placed to convert communication current of the CAN communication into bus voltage. It consists of a resister and condenser. Two terminus circuits are necessary on a bus.
CAN J/C
The CAN J/C is a junction designed for CAN communication, which stores a terminus circuit.
ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM |
Skid control ECU with actuator (3GR-FE, 3GR-FSE)
Skid control ECU (3UZ-FE)
Yaw rate sensor
Steering sensor
Television camera ECU
Seat belt control ECU
Distance control ECU
Absorber control ECU
ECM
Gateway ECU
Clearance warning ECU
Power steering ECU
Steering control ECU
DIAGNOSTIC CODE FOR CAN COMMUNICATION SYSTEM |
DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0122, U0123, U0124, U0126, U0132, U0145, U1101, U0130, U0131, U0145, U0114, U0146, U0105, U0121, U0104, U0235, U1102, 5C-42
REMARK FOR TROUBLESHOOTING |
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).
- NOTICE:
- Do not connect the tester directly to the DLC3 connector. Be sure to use a service wire.
DTCs regarding the CAN communication system can be checked using the intelligent tester.
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.
HOW TO DISTINGUISH THE CAN J/C CONNECTOR |
In the CAN communication system, the shape of all connectors connected to the CAN J/C is the same. The connectors connected to the CAN J/C can be distinguished by the colors of the bus line and the connecting side of the connector.
- HINT:
- See "TERMINALS OF ECU" (Click here) for bus line color or the type of connecting surface.