How To Proceed With Troubleshooting
- DTCs for the CAN communication system are as follows: U0073, U0100, U0101, U0123, U0124 and U0126.
- Refer to the appropriate troubleshooting article of each system if DTCs regarding the CAN communication system are not output.
HINT:
Use the Techstream.
- INSPECT BATTERY VOLTAGE
Standard voltage
11 to 14 V
HINT:
If the voltage is below 11 V, recharge or replace the battery before proceeding.
NEXT: Go to next step
- CHECK AND CLEAR DTCs
HINT:
- CAN communication DTCs are output when there is an open or short in any of the communication wires. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU, the sensor itself also cause these DTCs to be output.
- If a CAN communication wire connector is disconnected with the ignition switch on (IG), the ECUs of the corresponding system and related systems record a DTC.
NEXT: Go to next step
- CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION
- Based on the vehicle equipment and specifications, confirm the systems that use CAN communication. Refer to DIAGNOSIS SYSTEM .
NEXT: Go to next step
- Based on the vehicle equipment and specifications, confirm the systems that use CAN communication. Refer to DIAGNOSIS SYSTEM .
- CHECK DLC3 BRANCH WIRE AND CAN NO. 1 BUS CIRCUIT MAIN WIRE (CANH - CANL) NOTE:
- Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.
- After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
- Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors. If the doors need to be opened in order to check the connectors, open the doors and leave them open.
HINT:
Operating the ignition switch, any other switches, or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
- Turn the ignition switch off.
- Measure the resistance according to the value(s) in the table below.
Resistance
Tester Connection Condition Specified value Proceed to D20-6 (CANH) - D20-14 (CANL) Ignition switch off 54 to 69 Ω A D20-6 (CANH) - D20-14 (CANL) Ignition switch off 70 Ω or higher B D20-6 (CANH) - D20-14 (CANL) Ignition switch off Below 54 Ω C B → GO TO CAN MAIN WIRE FOR DISCONNECTION. Refer to CAN Main Bus Line for Disconnection .
C → GO TO CHECK CAN BUS LINES FOR SHORT CIRCUIT. Refer to Check CAN Bus Lines for Short Circuit .
A: Go to next step
- CHECK FOR SHORT TO GND IN CAN NO. 1 BUS (CANH, CANL - CG)
- Turn the ignition switch off.
- Measure the resistance according to the value(s) in the table below.
Resistance
Tester Connection Condition Specified value D20-6 (CANH) - D20-4 (CG) Ignition switch off 200 Ω or more D20-14 (CANL) - D20-4 (CG) Ignition switch off 200 Ω or more NG → GO TO CHECK CAN BUS LINE FOR SHORT TO GND. Refer to Check CAN Bus Line for Short to GND .
OK: Go to next step
- CHECK FOR SHORT TO +B IN CAN NO. 1 BUS (CANH, CANL - BAT)
- Disconnect the negative battery terminal.
- Measure the resistance according to the value(s) in the table below.
Resistance
Tester Connection Condition Specified value D20-6 (CANH) - D20-16 (BAT) Negative battery terminal disconnected 6 kΩ or more D20-14 (CANL) - D20-16 (BAT) Negative battery terminal disconnected 6 kΩ or more NG → GO TO CHECK CAN BUS LINE FOR SHORT TO +B. Refer to Check CAN Bus Line for Short to +B .
OK: Go to next step
- CHECK FOR INSTALLED SYSTEMS (ECUS & SENSORS) THAT ADOPT CAN COMMUNICATION
- Check which of the following is adopted: vehicle stability control.
NEXT: Go to next step
- Check which of the following is adopted: vehicle stability control.
- CHECK ECUS CONNECTED TO CAN BUS
- Using Techstream, select "CAN Bus Check" from the "System Select".
- Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.
Result
Result Proceed to All ECUs and sensors connected to the CAN communication system are displayed on the screen.
(CAN bus circuit is currently normal)A One of the ECUs and sensors connected to the CAN communication system is not displayed on the screen.
(Open in ECU or sensor branch wires, or communication interrupted)B Some ECUs and sensors repeatedly appear and disappear from the screen, during this check.
(Open in one side of ECU or sensor branch wires)C NOTE:- The systems (ECUs, sensors) that adopt CAN communication vary depending on the vehicle and option settings. Check which systems (ECUs, sensors) are installed on the vehicle.
- Non-installed ECUs or sensors are not displayed. Do not mistake them for being in the communication stop mode.
- Techstream and the tester display are affected by signals output from other ECUs which have an open circuit in either of their CAN branch wires.
B → GO TO "COMMUNICATION STOP MODE TABLE". Refer to PROBLEM SYMPTOMS TABLE .
C → GO TO "OPEN IN ONE SIDE OF CAN BRANCH WIRE". Refer to Open in One Side of CAN Sub Bus Line .
A: Go to next step
- DTC COMBINATION TABLE
- Confirm trouble according to the combination of output DTCs regarding the CAN communication system. Refer to DIAGNOSIS SYSTEM .
HINT:
- Sometimes CAN communication system DTCs are output, but all the ECUs and sensors connected to the CAN communication system are displayed on the Techstream. In this case, previous or history DTCs may indicate the cause of the problem.
- ECUs related to a problem in the CAN bus will store DTCs to indicate communication malfunctions. The communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to 9 the DTC combination table for the CAN bus.
NEXT: Go to next step
- Confirm trouble according to the combination of output DTCs regarding the CAN communication system. Refer to DIAGNOSIS SYSTEM .
- CIRCUIT INSPECTION
NEXT: Go to next step
- IDENTIFICATION OF PROBLEM
NEXT: Go to next step
- REPAIR OR REPLACE
NEXT: Go to next step
- CONFIRMATION TEST
NEXT → END