CAN COMMUNICATION SYSTEM(w/ Central Gateway ECU) 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 V bus has a termination circuit with a resistor of 60 Ω, and the bus 1, bus 2, bus 3, sub bus 1, sub bus 13 and sub bus 15 each have termination circuits with two resistors of 120 Ω.
5. The CAN communication system is composed of 7 buses.
DEFINITION OF TERMS
1. Main bus
  1. The main bus is a wire harness between the two terminating resistors on the bus. This is the main bus in the CAN communication system.
2. Branch
  1. A branch is a wire harness which diverges from the main bus 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 (for LHD)
1. Bus 1
  1. Driving support ECU assembly*1
  2. Forward recognition camera*1
  3. Millimeter wave radar sensor assembly*1
  4. Blind spot monitor sensor LH*2
  5. Hybrid vehicle control ECU assembly
  6. Central gateway ECU
2. Bus 2
  1. Combination meter assembly
  2. Main body ECU (multiplex network body ECU)
  3. Steering sensor
  4. Hybrid vehicle control ECU assembly
  5. Brake booster with master cylinder assembly (skid control ECU)
  6. Power steering ECU with motor assembly
  7. Airbag sensor assembly
  8. Air conditioning amplifier assembly
  9. ECM
  10. Certification ECU (smart key ECU assembly)
  11. Clearance warning ECU assembly
  12. Headlight leveling ECU (headlight swivel ECU assembly)
  13. Central gateway ECU
3. Bus 3
  1. Radio receiver assembly
  2. Telematics transceiver*3
  3. Central gateway ECU
4. Sub Bus 1
  1. Main body ECU (multiplex network body ECU)
  2. Multiplex tilt and telescopic ECU*4
  3. Outer mirror control ECU assembly LH*5
  4. Outer mirror control ECU assembly RH*5
  5. Front power seat switch LH*5
  6. Front power seat switch RH*6
  7. Luggage closer motor assembly*7
  8. Rear television camera assembly*8
5. Sub Bus 13*1
  1. Driving support ECU assembly
  2. Forward recognition camera
  3. Millimeter wave radar sensor assembly
6. Sub Bus 15
  1. ECM
  2. Hybrid vehicle control ECU assembly
  3. Brake booster with master cylinder assembly (skid control ECU)
    
    Tech Tips
    
    *1: w/ Lexus Safety System +
    
    *2: w/ Blind Spot Monitor System
    
    *3: w/ Manual (SOS) Switch
    
    *4: w/ Power Tilt and Power Telescopic Steering Column System
    
    *5: w/ Seat Position Memory System (for Driver Side)
    
    *6: w/ Seat Position Memory System (for Front Passenger Side)
    
    *7: w/ Power Trunk Lid System
    
    *8: w/ Parking Assist Monitor System without Parallel Parking Assist Function
ECUS OR SENSORS WHICH COMMUNICATE THROUGH CAN COMMUNICATION SYSTEM (for RHD)
1. Bus 1
  1. Driving support ECU assembly*1
  2. Forward recognition camera*1
  3. Millimeter wave radar sensor assembly*1
  4. Blind spot monitor sensor LH*2
  5. Hybrid vehicle control ECU assembly
  6. Central gateway ECU
2. Bus 2
  1. Combination meter assembly
  2. Main body ECU (multiplex network body ECU)
  3. Steering sensor
  4. Hybrid vehicle control ECU assembly
  5. Brake booster with master cylinder assembly (skid control ECU)
  6. Power steering ECU with motor assembly
  7. Airbag sensor assembly
  8. Air conditioning amplifier assembly
  9. ECM
  10. Certification ECU (smart key ECU assembly)
  11. Clearance warning ECU assembly
  12. Headlight leveling ECU (headlight swivel ECU assembly)
  13. Central gateway ECU
3. Bus 3
  1. Radio receiver assembly
  2. Central gateway ECU
4. Sub Bus 1
  1. Main body ECU (multiplex network body ECU)
  2. Multiplex tilt and telescopic ECU*3
  3. Outer mirror control ECU assembly LH
  4. Outer mirror control ECU assembly RH
  5. Front power seat switch LH*4
  6. Front power seat switch RH
  7. Luggage closer motor assembly*5
  8. Rear television camera assembly*6
5. Sub Bus 13*1
  1. Driving support ECU assembly
  2. Forward recognition camera
  3. Millimeter wave radar sensor assembly
6. Sub Bus 15
  1. ECM
  2. Hybrid vehicle control ECU assembly
  3. Brake booster with master cylinder assembly (skid control ECU)
    
    Tech Tips
    
    *1: w/ Lexus Safety System +
    
    *2: w/ Blind Spot Monitor System
    
    *3: w/ Power Tilt and Power Telescopic Steering Column System
    
    *4: w/ Seat Position Memory System (for Front Passenger Side)
    
    *5: w/ Power Trunk Lid System
    
    *6: w/ Parking Assist Monitor System without Parallel Parking Assist Function
CIRCUIT DESCRIPTION
1. The V bus has a termination circuit with a resistor of 60 Ω.
2. The bus 1, bus 2, bus 3, sub bus 1, sub bus 13 and sub bus 15 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 main lines. If there is any trouble in the DLC3 or the DLC3 main lines, ECUs on the CAN cannot output DTCs to the GTS.
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 connectors Click here.