CAN COMMUNICATION SYSTEM > SYSTEM DESCRIPTION

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1. The Control Area Network (CAN) is a serial data communication system for real time application. It is a vehicle multiplex communication system which has a high communication speed and the ability to detect malfunctions.
   

2. By pairing the CANH and CANL bus wires, the CAN performs communication based on differential voltage.
   

3. Many ECUs or 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 wire.
   

1. Main bus wire
   
   

   1. The main bus wire is a wire harness between the two terminating resistors on the bus (communication wire). This is the main bus in the CAN communication system.
      

2. Branch wire
   
   

   1. The branch wire is a wire harness which diverges from the main bus wire to an ECU or sensor.
      

3. Terminating resistors
   
   

   1. The termination circuit is a circuit which converts the communication current of CAN communication into the bus voltage. It consists of a resistor and condenser. Two termination circuits are necessary on the bus.
      

1. CAN No. 1 Bus
   
   

   1. ECM
      

   2. Power management control ECU
      

   3. Combination meter
      

   4. Skid control ECU (Brake booster with master cylinder)
      

   5. Steering angle sensor
      

   6. Yaw rate sensor
      

   7. Power steering ECU
      

   8. Center airbag sensor assembly
      

   9. Certification ECU
      

   10. Main body ECU
       

   11. Transmission control ECU
       

   12. Navigation ECU (Navigation receiver assembly)*1
       

2. CAN No. 2 Bus
   
   

   1. Power management control ECU
      

   2. Driving support ECU*2
      

   3. Seat belt control ECU*3
      

   4. Parking assist ECU*4
      

3. Power Management Bus
   
   

   1. Power management control ECU
      

   2. ECM
      

   3. Skid control ECU (Brake booster with master cylinder)
      

   4. Air conditioning amplifier
      

4. Parking Assist Bus*2
   
   

   1. Driving support ECU
      

   2. Millimeter wave radar sensor
      

      HINT:

      *1: w/ Navigation system

      *2: w/ Dynamic radar cruise control system

      *3: w/ Pre-crash safety system

      *4: w/ Intelligent parking assist system

1. The CAN No. 1 bus, CAN No. 2 bus, power management bus and parking assist bus each have termination circuits with two resistors of 120 Ω. High speed communication at 500 kbps is possible.
   

1. 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 branch wires. If there is any trouble in the DLC3 or the DLC3 branch wires, ECUs on the CAN network cannot output codes to the intelligent tester.
   

2. Trouble in the CAN buses (communication wires) can be checked by measuring the resistance between terminals of the DLC3. However, an open circuit in a branch wire other than the DLC3 branch wires cannot be checked from the DLC3.
   

   NOTICE:

   Do not insert the tester probes directly into the DLC3. Be sure to use service wires.

1. DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0104, U0122, U0123, U0124, U0126, U0129, U0131, U0140, U0142, U0146, U0151, U0155, U0164, U0235, U0293, U0327, U1000, U1002, U1100, U1104, U1105, U1107, U110B and U1133.
   

1. Trouble in the CAN bus (communication line) can be checked through the DLC3 (except when there is a wire break other than in the branch wire of the DLC3).
   

   NOTICE:

   Do not insert the tester probes directly into the DLC3. Be sure to use service wires.

2. DTCs regarding the CAN communication system can be checked using the intelligent tester.
   

3. The CAN communication system cannot detect trouble in the branch wires for the DLC3 even though the DLC3 is also connected to the CAN communication system.
   

1. In the CAN communication system, the shape of connectors connected to the CAN junction connector which has an earth terminal is the same. The connectors connected to the CAN junction connector can be distinguished by the colors of the bus wires and the connecting side of the junction connector.
   

   HINT:

   See Terminals of ECU for bus wire color or the shape of connecting surface (Click here).