Can Communication System (For Lhd Without Central Gateway Ecu) System Description

The CAN (Controller Area Network) is a serial data communication system for real-time application. It is a vehicle multiplex communication system which has a high communication speed (500 kbps) and the ability to detection malfunctions.

By pairing the CANH and CANL bus lines, the CAN performs communication based on differential voltages.

Many ECUs (sensors) installed on the vehicle operate by sharing information and communication with each other.

The CAN has 2 resistors of 120 Ω which are necessary to communicate using the CAN main wire.

CAN main wire

1. The CAN main wire is a wire harness between the 2 termination circuits on the bus (communication line). This is the CAN main bus in the CAN communication system.
   

CAN branch wire

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

Termination circuits

1. The termination circuit is a circuit which converts the communication current of the CAN communication into the bus voltage. It consists of a resistor and capacitor. 2 termination circuits are necessary on a bus.
   

CAN junction connector

1. The CAN junction connector is designed so that it can be used with CAN communication which has a termination circuit and CAN communication which does not have a termination circuit.
   

The V bus and sub bus 1 have, termination circuits with a resistance of 120 Ω x 2. High speed communication at 250 kbps and 500 kbps is possible.

V Bus

1. ECM
   

2. DLC3
   

3. Combination meter assembly
   

4. Main body ECU (multiplex network body ECU)
   

5. Spiral with sensor cable sub-assembly (steering angle sensor)
   

6. Airbag sensor assembly
   

7. Headlight leveling ECU assembly
   

8. Master cylinder solenoid (skid control ECU)
   

9. Steering control ECU*1
   

10. Power steering ECU assembly*2
    

11. 4WD control ECU
    

12. Tire pressure warning ECU*3
    

13. Air conditioning amplifier assembly
    

14. Certification ECU (smart key ECU assembly)*4
    

15. Multi-media module receiver assembly*5
    

16. Radio and display receiver assembly*6
    

17. Bus buffer ECU*7
    

    1. *1: w/ Variable Gear Ratio Steering System
       
    2. *2: w/ Variable Flow Control Solenoid Valve
       
    3. *3: w/ Tire Pressure Warning System
       
    4. *4: w/ Entry and Start System
       
    5. *5: for Multi-media Module Receiver Type
       
    6. *6: for Radio and Display Type
       
    7. *7: w/ Bus Buffer ECU
       

Sub Bus 1

1. Main body ECU (multiplex network body ECU)
   

2. Outer mirror control ECU assembly LH*1
   

3. Outer mirror control ECU assembly RH*1
   

4. Power seat switch assembly*1
   

5. Multiplex tilt and telescopic ECU*2
   

6. Power back door unit assembly (power back door ECU)*3
   

7. No. 2 main body ECU*4
   

   1. *1: w/ Memory
      
   2. *2: w/ Power Tilt and Power Telescopic Steering Column System
      
   3. *3: w/ Power Back Door System
      
   4. *4: w/ Tail Gate Closer System
      

DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0114, U0120, U0122, U0123, U0124, U0126, U0129, U0130, U0131, U0140, U0141, U0142, U0151, U0155, U0163, U0164, U0182, U0199, U0200, U0208, U0230, U0327, U1000, U1002, U1115, U1117.

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

DTCs regarding the CAN communication system can be checked using the GTS.

The CAN communication system cannot detect trouble in the CAN branch wire of the DLC3 even though the DLC3 is also connected to the CAN communication system.

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 line and the connecting side of the connector.

HINT:

See "Terminals of ECU" (Click here) for bus line color or the type of connecting surface.