CAN COMMUNICATION SYSTEM (for RHD) SYSTEM DESCRIPTION

BRIEF DESCRIPTION
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.
2. Using the CANH and CANL bus lines as a pair, CAN communication is performed using a voltage differential. (A base voltage is applied to the pair of lines 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 CAN has two resistors of 120 Ω which are necessary to enable communication.
5. Control system CAN is composed of 5 buses*1 or 7 buses*2.
  - *1: w/o Dynamic Rear Steering System
  - *2: w/ Dynamic Rear Steering System
DEFINITION OF TERMS
1. Main bus line
  1. The main bus line is a wire harness between the two terminating resistors on the bus. This is the main bus in the CAN communication system.
2. Branch line
  1. The branch line is a wire harness which diverges from the main bus line to an ECU or sensor.
3. Terminating resistors
  1. Two resistors of 120 Ω are installed in parallel across the ends of the CAN main bus lines. They are called terminating resistors. These resistors allow the changes of the voltage differential between the CAN bus lines 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.
ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM (w/o Dynamic Rear Steering System)
1. V Bus
  1. ECM
  2. Parking brake ECU assembly
  3. Main body ECU (multiplex network body ECU)
  4. Skid control ECU assembly
  5. Combination meter assembly
  6. Spiral with sensor cable sub-assembly (steering angle sensor)
  7. Yaw rate sensor
  8. Multi-media module receiver assembly
  9. Power steering ECU assembly
  10. Center airbag sensor assembly
  11. Air conditioning amplifier assembly
  12. Network gateway ECU
  13. Certification ECU (smart key ECU assembly)
  14. Power management control ECU
2. Sub Bus 2
  1. Network gateway ECU
  2. Power management control ECU
  3. Headlight swivel ECU assembly (AFS ECU)
  4. Absorber control ECU*1
  5. Driving support ECU assembly*2
  6. Clearance warning ECU assembly*3
  7. Blind spot monitor sensor RH*4
  8. Blind spot monitor sensor LH*4
  9. Seat belt control ECU*5
    - *1: w/ Adaptive Variable Suspension System
    - *2: w/ Dynamic Radar Cruise Control System
    - *3: w/ LEXUS Parking Assist-sensor System
    - *4: w/ Blind Spot Monitor System
    - *5: w/ Pre-cash Safety System
3. Sub Bus 1
  1. Main body ECU (multiplex network body ECU)
  2. Luggage closer motor assembly*1
  3. Front multiplex network door ECU RH
  4. Front multiplex network door ECU LH
  5. Multiplex tilt and telescopic ECU
  6. Position control ECU assembly RH*2
  7. Power seat switch assembly*3
  8. Position control ECU assembly LH*4
    - *1: w/ Power Trunk Lid System
    - *2: except Standard Seat Type
    - *3: for Standard Seat Type
    - *4: for Luxury Seat Type
4. Sub Bus 13*1
  1. Driving support ECU assembly
  2. Millimeter wave radar sensor assembly
  3. Driver monitor ECU assembly*2
  4. Lane recognition camera sensor assembly*3
  5. No. 1 night view ECU*4
    - *1: w/ Dynamic Radar Cruise Control System
    - *2: w/ Driver Monitor Camera
    - *3: w/ Lane-keeping Assist System
    - *4: w/ Night View System
5. Sub Bus 15
  1. ECM
  2. Skid control ECU assembly
  3. Power management control ECU
ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM (w/ Dynamic Rear Steering System)
1. V Bus
  1. ECM
  2. Parking brake ECU assembly
  3. Main body ECU (multiplex network body ECU)
  4. Skid control ECU assembly
  5. Combination meter assembly
  6. Spiral with sensor cable sub-assembly (steering angle sensor)
  7. Yaw rate sensor
  8. Multi-media module receiver assembly
  9. Power steering ECU assembly
  10. Center airbag sensor assembly
  11. Front steering control ECU
  12. Air conditioning amplifier assembly
  13. Network gateway ECU
  14. Certification ECU (smart key ECU assembly)
  15. Power management control ECU
2. Sub Bus 18
  1. Network gateway ECU
  2. Power management control ECU
  3. Headlight swivel ECU assembly (AFS ECU)
  4. Absorber control ECU*1
  5. Driving support ECU assembly*2
  6. Clearance warning ECU assembly*3
  7. Blind spot monitor sensor RH*4
  8. Blind spot monitor sensor LH*4
  9. Seat belt control ECU*5
    - *1: w/ Adaptive Variable Suspension System
    - *2: w/ Dynamic Radar Cruise Control System
    - *3: w/ LEXUS Parking Assist-sensor System
    - *4: w/ Blind Spot Monitor System
    - *5: w/ Pre-cash Safety System
3. Sub Bus 19
  1. Skid control ECU assembly
  2. Network gateway ECU
  3. Front steering control ECU
  4. Power steering ECU assembly
  5. Absorber control ECU*1
  6. Driving support ECU assembly*2
  7. Rear steering control ECU
    - *1: w/ Adaptive Variable Suspension System
    - *2: w/ Dynamic Radar Cruise Control System
4. Sub Bus 1
  1. Main body ECU (multiplex network body ECU)
  2. Luggage closer motor assembly*
  3. Front multiplex network door ECU RH
  4. Front multiplex network door ECU LH
  5. Multiplex tilt and telescopic ECU
  6. Position control ECU assembly RH
    - *: w/ Power Trunk Lid System
5. Sub Bus 13*1
  1. Driving support ECU assembly
  2. Millimeter wave radar sensor assembly
  3. Driver monitor ECU assembly*2
  4. Lane recognition camera sensor assembly*3
  5. No. 1 night view ECU*4
    - *1: w/ Dynamic Radar Cruise Control System
    - *2: w/ Driver Monitor Camera
    - *3: w/ Lane-keeping Assist System
    - *4: w/ Night View System
6. Sub Bus 15
  1. ECM
  2. Skid control ECU assembly
  3. Power management control ECU
CIRCUIT DESCRIPTION
1. w/o Dynamic Rear Steering System:
  
  The V bus, sub bus 1, sub bus 2, sub bus 13 and sub bus 15 and each have termination circuits with two resistors of 120 Ω.
2. w/ Dynamic Rear Steering System:
  
  The V bus, sun bus 1, sub bus 13, sub bus 15, sub bus 18, sub bus 19 and local bus and each have termination circuits with two resistors of 120 Ω.
TROUBLESHOOTING REMARKS
1. DTCs for the CAN communication system can be checked using the GTS. The DLC3 is connected to the CAN communication system, but no DTCs exist regarding problems in the DLC3 or the DLC3 branch lines. If there is any trouble in the DLC3 or the DLC3 branch lines, ECUs on the CAN network cannot output codes to the GTS.
2. Trouble in the CAN V bus (communication lines) can be checked by measuring the resistance between terminals of the DLC3. However, an open circuit in a branch line other than the DLC3 branch lines cannot be checked from the DLC3 (except branch line of the DLC3).
  
  Note
  
  Do not insert the tester probes directly into the DLC3. Be sure to use service wires.
DIAGNOSTIC TROUBLE CODES FOR CAN COMMUNICATION SYSTEM

Tech Tips

See Diagnosis System Click here.
HOW TO DISTINGUISH CONNECTOR OF CAN JUNCTION CONNECTOR
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 lines and the connecting side of the junction connector.
  
  Tech Tips
  
  See Terminals of ECU for bus line color or the shape of connecting surface Click here.