System Description [10/2015 - ]

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.
   Fig 1: Controller Area Network (CAN) Serial Data Communication System Diagram

   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. The CAN communication system 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
   2. DLC3
2. Bus 2
   1. ECM
   2. Parking brake ECU assembly
   3. Main body ECU (multiplex network body ECU)
   4. Skid control ECU assembly
   5. Steering angle sensor
   6. Airbag sensor assembly
   7. Yaw rate sensor
   8. Certification ECU (smart key ECU assembly)
   9. Air conditioning amplifier assembly
   10. Power steering ECU assembly
   11. Front steering control ECU*1
   12. Central gateway ECU
   13. Combination meter mirror ECU*2
   14. Combination meter assembly
   15. Power management control ECU
       1. *1: w/ Variable Gear Ratio Steering System
       2. *2: w/ Headup Display System
3. Bus 3
   1. Central gateway ECU
   2. Multi-media module receiver assembly
   3. DCM (telematics transceiver)*
      1. *: w/ Manual (SOS) Switch
4. Bus 4
   1. Skid control ECU assembly
   2. Absorber control ECU*1
   3. Power steering ECU assembly
   4. Front steering control ECU*2
   5. Central gateway ECU
   6. Driving support ECU assembly*3
   7. Rear steering control ECU*4
      1. *1: w/ Adaptive Variable Suspension System
      2. *2: w/ Variable Gear Ratio Steering System
      3. *3: w/ Pre-collision System
      4. *4: w/ Dynamic Rear Steering System
5. Bus 5
   1. Central gateway ECU
   2. Headlight ECU sub-assembly LH
   3. Power management control ECU
   4. Absorber control ECU*1
   5. Driving support ECU assembly*2
   6. Forward recognition camera*2
   7. Millimeter wave radar sensor assembly*2
   8. Clearance warning ECU assembly*3
   9. Rear television camera assembly
   10. Blind spot monitor sensor RH*4
       1. *1: w/ Adaptive Variable Suspension System
       2. *2: w/ Pre-collision System
       3. *3: w/ Intuitive Parking Assist System
       4. *4: w/ Blind Spot Monitor 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 assembly LH*3
   5. Power seat switch assembly*4
   6. Position control ECU assembly RH*5
   7. Front multiplex network door ECU LH
   8. Front multiplex network door ECU RH
   9. Multiplex tilt and telescopic ECU
      1. *1: w/ Power Trunk Lid System
      2. *2: w/o Power Trunk Lid System
      3. *3: except Standard Seat Type
      4. *4: for Standard Seat Type
      5. *5: for Luxury Seat Type
7. Sub Bus 15
   1. ECM
   2. Skid control ECU assembly
   3. Power management control ECU

1. The V bus has a termination circuit with a resistor of 60 Ω.
2. The bus 2, bus 3, bus 4, bus 5, sub bus 1 and sub bus 15 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.

HINT: 

See Diagnosis System

Refer to DIAGNOSIS SYSTEM [10/2015 - ]

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 bus wire color or the connecting side of the connector.

   TERMINALS OF ECU [10/2015 - ]