System Description [09/2016 - 09/2017]

1. The Controller 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.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Using the CANH and CANL bus wires as a pair, CAN communication is performed using a voltage differential. (A base voltage is applied to the pair of wires and a voltage differential is created when communicating.)
3. Many ECUs or sensors installed on the vehicle operate by sharing information and communicating with each other.
4. The V bus has termination circuits with two resistors of 60 Ω, and the bus 2, bus 3, bus 4, bus 5 and sub bus 1 each have termination circuits with two resistors of 120 Ω.
5. Control system CAN is composed of 6 buses.

1. CAN main wire
   1. The CAN main wire is a wire harness between the 2 termination circuits on the bus (communication wire). This is the main bus in the CAN communication system.
2. CAN branch wire
   1. The CAN branch wire is a wire harness which diverges from the main wire to an ECU or sensor.
3. Termination circuits
   1. Two resistors of 120 Ω are installed in parallel across the ends of the CAN main bus wires. They are called terminating resistors. These resistors allow the changes of the voltage differential between the CAN bus wires to be accurately judged. To allow proper function of CAN communication, it is necessary to have both terminating resistors installed. Since the two resistors are installed in parallel, this results in a measurement of approximately 60 Ω.

1. V Bus
   1. Central Gateway ECU (Network Gateway ECU)
   2. DLC3
2. Bus 2
   1. ECM
   2. Parking Brake ECU Assembly
   3. Air Conditioning Amplifier Assembly
   4. Torque Vectoring Differential ECU Assembly
   5. Brake Actuator Assembly (Skid Control ECU)
   6. Main Body ECU (Multiplex Network Body ECU)
   7. Spiral Cable with Sensor Sub-assembly (Steering Angle Sensor)
   8. Certification ECU (Smart Key ECU Assembly)
   9. Yaw Rate Sensor (Yaw Rate and Acceleration Sensor)
   10. Headlight Light Control ECU Sub-assembly LH
   11. Airbag ECU Assembly
   12. Stereo Component Equalizer Assembly
   13. Combination Meter Mirror ECU*1
   14. Power Steering ECU Assembly
   15. Central Gateway ECU (Network Gateway ECU)
   16. Combination Meter Assembly
       1. *1: w/ Headup Display
3. Bus 3
   1. Central Gateway ECU (Network Gateway ECU)
   2. Radio Receiver Assembly
   3. DCM (Telematics Transceiver)*1
      1. *1: w/ Telematics Transceiver
4. Bus 4
   1. ECM
   2. Central Gateway ECU (Network Gateway ECU)
   3. Roll Rate and Vertical Acceleration Sensor (Yaw Rate Sensor)
   4. Driving Support ECU Assembly*1
   5. Brake Actuator Assembly (Skid Control ECU)
   6. Torque Vectoring Differential ECU Assembly
      1. *1: w/ Pre-collision System
5. Bus 5
   1. Central Gateway ECU (Network Gateway ECU)
   2. Television Camera Assembly RR
   3. Blind Spot Monitor Sensor RH*1
   4. Clearance Warning ECU Assembly*2
   5. Forward Recognition Camera*3
   6. Driving Support ECU Assembly*3
   7. Millimeter Wave Radar Sensor Assembly*3
   8. Absorber Control ECU
      1. *1: w/ Blind Spot Monitor System
      2. *2: w/ Intuitive Parking Assist System
      3. *3: w/ Pre-collision System
6. Sub Bus 1
   1. Main Body ECU (Multiplex Network Body ECU)
   2. Luggage Closer Motor Assembly*1
   3. Multiplex Network Door ECU*2
   4. Position Control ECU and Switch Assembly LH
   5. Position Control ECU and Switch Assembly RH
   6. Front Multiplex Network Door ECU LH
   7. Front Multiplex Network Door ECU RH
   8. Multiplex Tilt and Telescopic ECU
      1. *1: w/ Power Trunk Lid System
      2. *2: w/o Power Trunk Lid System

1. The V bus has a termination circuit with a resistor of 60 Ω.
2. The bus 2, bus 3, bus 4, bus 5 and sub bus 1 each have termination circuits with two resistors of 120 Ω.

1. DTCs for the CAN communication system can be checked using the Techstream. 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 a malfunction in the DLC3 or the DLC3 branch wires, ECUs on the CAN cannot output DTCs to the Techstream.
2. Malfunctions in the CAN V bus (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 (except for the DLC3 branch wires).
   NOTE:

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

HINT: 

See Diagnosis System

Refer to DIAGNOSIS SYSTEM [09/2016 - 09/2017]

1. 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 wire and the connecting side of the connector.

   HINT: 

   Refer to "Terminals of ECU" for the bus wire color or the connecting side of the connector.

   Refer to TERMINALS OF ECU [09/2016 - 09/2017]