How to Proceed With Troubleshooting

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING

HOW TO PROCEED WITH TROUBLESHOOTING
NOTICE:
- DTCs for the CAN communication system are as follows: U0073, U0100, U0122, U0123, U0124, U0126, U0129 and B1499.
- Refer to the troubleshooting for each system if DTCs regarding the CAN communication system are not output.
- 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 in operation.
- 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 doors need to be opened in order to check connectors, open the doors and leave them open.
HINT: Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

1. CHECK CAN BUS LINE
HINT:
- Check the CAN bus line. Check CAN Bus Line

NEXT -- Continue to next step.
2. CHECK INSTALLED SYSTEMS (ECUS AND SENSORS) THAT ADOPT CAN COMMUNICATION
NEXT -- Continue to next step.
3. CHECK AND CLEAR DTCS
NEXT -- Continue to next step.
4. CHECK CAN COMMUNICATION USING TECHSTREAM
(a) Select "Communication Bus Check" Diagnosis System.

Result





NOTICE:
- The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and option settings. Check which systems (ECUs and sensors) are installed on the vehicle Diagnosis System.
- Non-installed ECUs or sensors are not displayed. Do not mistake them for being in communication stop mode.
- If two or more ECUs or sensors are not displayed on the Techstream, perform troubleshooting for open in one side of the CAN branch wire for each undisplayed ECU or sensor. (Open circuit in CAN branch wire)

B -- GO TO COMMUNICATION STOP MODE TABLE
C -- GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE
A -- Continue to next step.
5. DTC COMBINATION TABLE
(a) Confirm trouble according to the combination of output DTCs regarding the CAN communication system.
HINT: Previous CAN communication system DTCs may be the cause if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on the Techstream "Communication Bus Check" screen.

NEXT -- Continue to next step.
6. INSPECT CIRCUIT
NEXT -- Continue to next step.
7. IDENTIFY PROBLEM
NEXT -- Continue to next step.
8. REPAIR OR REPLACE
NEXT -- Continue to next step.
9. PERFORM CONFIRMATION TEST
NEXT -- END