Information Bus: Description and Operation

CAN COMMUNICATION SYSTEM:

SYSTEM DIAGRAM




HINT:
- The skid control ECU stores DTCs and performs DTC communication by receiving information from the steering angle sensor and yaw rate sensor. These sensors cannot store DTCs or perform DTC communication.
- The ECM uses the CAN communication system to perform DTC communication instead of the conventional serial communication line (SIL).

SYSTEM DESCRIPTION

1. BRIEF DESCRIPTION
(a) 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.
(b) By paring the CANH and CANL bus lines, the CAN performs communication based on differential voltages.
(c) Many ECUs (sensors) installed on the vehicle operate by sharing information and communicating with each other.
(d) The CAN has two resistors of 120 Ohms that are necessary for communication with the main bus line.
2. DEFINITION OF TERMS
(a) 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.
(b) Sub bus line
(1) The sub bus line is a wire harness which diverges from the main bus line to an ECU or sensor.
(c) 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.
(d) CAN junction connector
(1) The CAN junction connector is a junction designed for CAN communication, which stores a terminus circuit.
3. COMPONENTS WHICH COMMUNICATE THROUGH THE CAN COMMUNICATION SYSTEM
(a) Skid control ECU
(b) Steering angle sensor
(c) Yaw rate and deceleration sensor
(d) ECM
4. DIAGNOSTIC CODES FOR THE CAN COMMUNICATION SYSTEM
(a) DTCs for the CAN communication system are as follows: U0073/94, U0123/62, U0124/95, U0126/63, U0100/65
5. REMARKS FOR TROUBLESHOOTING
(a) Trouble in the CAN bus (communication line) can be checked from the DLC3 (except a wire break in lines other than the DLC3 sub bus line).
(b) The CAN communication system cannot detect trouble in the DLC3 sub bus line even though the DLC3 is also connected to the CAN communication system.
6. HOW TO DISTINGUISH THE CAN JUNCTION CONNECTOR
(a) In the CAN communication system, the shape of all connectors connected to the CAN junction connector is the same. The connectors connected to the CAN junction connector can be distinguished by the colors of the bus line and the connecting side of the connector.
HINT: See TERMINALS OF ECU Pinout Values and Diagnostic Parameters for bus line color or the type of connecting surface.