How to Proceed With Troubleshooting
NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING
NOTICE:
* DTCs for the CAN communication system are as follows: U0073, U0100, U0123, U0124, U0126, U0129, U0131, U0142, U0151 and U0155.
* Refer to the troubleshooting section 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.
* *: Use the Techstream.
1. VEHICLE BROUGHT TO WORKSHOP
NEXT -- Continue to next step.
2. 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 -- Continue to next step.
3. CHECK AND CLEAR DTC*
(a) Using the Techstream, perform the ALL DTC check.
HINT
* If a CAN communication trouble code that informs that an ECU or sensor has a power malfunction or interior malfunction is causing a communication stop, the problem may not be in the communication line. There is a high possibility that the ECU or sensor has a signal transmission failure. Therefore, first troubleshoot any DTCs related to the ECU or sensor.
* When CAN communication related connectors are disconnected with the ignition switch ON or ACC, the ECU related to the connector and ECUs of related systems will store a CAN communication DTC.
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4. CHECK CAN BUS LINE
HINT
Check the CAN bus line Check CAN Bus Line.
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5. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT ADOPT CAN COMMUNICATION
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Diagnosis System.
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6. 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.
* The ECUs and sensors that repeatedly appear and disappear from on screen during this check are considered normal. (The response to the Techstream and the tester display are affected by signals output from other ECUs which have an open circuit in either of their CAN bus branch wires.)
B -- GO TO COMMUNICATION STOP MODE Symptom Related Diagnostic Procedures
C -- GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE Open in One Side of CAN Branch Line
A -- Continue to next step.
7. DTC COMBINATION TABLE
(a) Confirm trouble according to the combination of output DTCs regarding the CAN communication system Diagnosis 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 the "Communication Bus Check" of the Techstream.
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8. INSPECT CIRCUIT
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9. IDENTIFICATION OF PROBLEM
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10. REPAIR OR REPLACE
NEXT -- Continue to next step.
11. PERFORM CONFIRMATION TEST
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