CAN Communication
SYSTEM DIAGRAMSystem Diagram:
HINT: The skid control ECU detects and stores steering sensor and yaw rate sensor DTCs and performs DTC communication by receiving information from the steering sensor and yaw rate sensor. These sensors cannot store DTCs or perform DTC communication.
SYSTEM DESCRIPTION
1. BRIEF DESCRIPTION
a. The CAN (Control 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 pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltage.
c. The HIGHLANDER uses the CAN communication system for communication between the following ECU and sensors in the ABS with EBD & BA & TRC & VSC system.
d. The CAN has two resistors of 120 Ohms which are necessary to communicate 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 that converts communication current of the CAN communication into bus voltage. It consists of a resistor and condenser. Two terminus circuits are necessary on a bus.
3. ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM
a. Skid control ECU
b. Yaw rate sensor
c. Steering sensor
4. DIAGNOSTIC CODE FOR CAN COMMUNICATION SYSTEM
a. DTCs for the CAN communication system are as follows: U0073, U0123, U0124, U0126
5. TROUBLESHOOTING REMARKS
a. DTCs for the CAN communication system can be checked using the intelligent tester. The DLC3 is connected to the CAN communication system, but no DTCs exist regarding problems in the DLC3 or the DLC3 sub bus lines. If there is trouble in the DLC3 or the DLC3 sub bus lines, ECUs on the CAN network cannot output codes to the intelligent tester.
b. Trouble in the CAN buses (communication lines) can be checked by measuring the resistance between terminals of the DLC3. However, an open circuit in a sub bus line other then the DLC3 sub bus lines cannot be checked from the DLC3.
NOTE: Do not insert the tester probes directly into the DLC3. Be sure to use a service wire.