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: U0001, U0073, U0100, U0104, U0110, U0122, U0123, U0124, U0126, U0129, U0130, U0131, U0132, U0146, U0235, U0293, U1101, and U1102
- Refer to the troubleshooting procedures of each system if DTCs regarding the CAN communication system are not output.
- Before measuring the resistance, leave the vehicle for at least 1 minute and do not operate the ignition switch, any switches or doors. If doors need to be opened in order to check connectors, open the doors and leave them open.
HINT:
- *: Use the Techstream.
- Operating the power switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

1. VEHICLE BROUGHT TO WORKSHOP
NEXT -- Continue to next step.
2. INSPECT BATTERY VOLTAGE
Standard voltage:
11 to 14 V
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.
NOTICE:
- If a CAN communication malfunction 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 power switch ON (IG or ACC), the ECU related to the connector and ECUs of related systems will store a CAN communication DTC.

NEXT -- Continue to next step.
4. CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION
(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Diagnosis System.
NEXT -- Continue to next step.
5. CHECK ECUS CONNECTED TO CAN BUS*
(a) Using the Techstream, Select "CAN Bus Check" from the "System Select".
(b) Wait 1 minute and then check the display of the connected ECUs and sensors.





NOTICE:
- ECUs and sensors that are not present will not be displayed. Be careful not to mistaken them for communication stop malfunctions.
HINT:
- If the display of an ECU is intermittent during the check, one side of an ECU or sensor branch wire is open. (The signal of the ECU is treated as noise, which affects the response and display of the Techstream.)
- The hybrid vehicle control ECU checks for proper ECU communication for ECUs that are connected to the CAN No. 2 bus circuit, and the results are displayed on the Techstream. If communication stops between an ECU and hybrid vehicle control ECU for 10 seconds or more, the ECU disappears from the Techstream display.
- For communication stop mode of ECUs connected to the CAN No. 2 bus circuit, refer to the DTC flowchart of the respective communication stop.

B -- GO TO DTC U1003 FLOWCHART
C -- GO TO HYBRID VEHICLE CONTROL ECU COMMUNICATION STOP MODE FLOWCHART
D -- GO TO PROBLEM SYMPTOMS TABLE
E -- GO TO OPEN IN ONE SIDE OF CAN BRANCH WIRE FLOWCHART
F -- Go to step 9
A -- Continue to next step.
6. CHECK DLC3 BRANCH WIRE AND CAN NO. 1 BUS CIRCUIT MAIN WIRE (CANH - CANL)





(a) Measure the resistance of the DLC3.
Standard resistance:






B -- GO TO "OPEN IN CAN MAIN WIRE"
C -- GO TO "SHORT IN CAN BUS LINES"
A -- Continue to next step.
7. CHECK CAN NO. 1 BUS CIRCUIT +B (BAT - CANH, CANL)





(a) Measure the resistance of the DLC3.
Standard resistance:






NG -- GO TO "SHORT TO B+ IN CAN BUS LINE"
OK -- Continue to next step.
8. CHECK CAN NO. 1 BUS CIRCUIT GND (CG - CANH, CANL)





(a) Measure the resistance of the DLC3.
Standard resistance:






NG -- GO TO "SHORT TO GND IN CAN BUS LINE"
OK -- Continue to next step.
9. CHECK COMMUNICATION MALFUNCTION DTC (PAST DTC CHECK)*
(a) Using the Techstream, Select "CAN Bus Check" from the "System Select".
(b) Write down all of the DTCs stored in each ECU.
HINT:
- If there are communication malfunction DTCs stored but the Techstream's "CAN Bus Check" screen displays all of the ECUs and sensors connected to the CAN system, the communication malfunction DTCs may be past malfunctions that are no longer present.
- For CAN No. 1 bus circuit main wire malfunctions, related ECUs are also detected. Therefore, determine the malfunctioning area based on all of the DTCs that are output.
- For CAN No. 2 bus circuit malfunctions, DTCs are output based on the detection of communication stop malfunctions of ECUs that are connected by the hybrid vehicle control ECU.
- During a network malfunction (main wire malfunction), the hybrid vehicle control ECU may erase stored DTCs in an attempt to reinstate communication.
- For DTCs regarding connected ECUs that are output when the CAN No. 2 bus circuit main wire is malfunctioning, refer to the DTC COMBINATION TABLE (Can No. 2 Bus Circuit Main Wire Past Malfunction).





B -- GO TO DTC U1003 FLOWCHART
C -- GO TO PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
10. CHECK DTC COMBINATION TABLE (CAN NO. 1 BUS CIRCUIT BRANCH WIRE OPEN PAST MALFUNCTION)
(a) Based on the combination of stored CAN communication system DTCs, determine which ECUs and sensors have a communication stop malfunction Diagnosis System.
NEXT -- Continue to next step.
11. PERFORM MALFUNCTION SIMULATION TEST (CAN NO. 1 BUS CIRCUIT MAIN WIRE PAST MALFUNCTION)*
(a) Using the Techstream, clear all DTCs.
(b) Perform a malfunction simulation test on all harnesses and connectors related to the CAN No. 1 bus circuit main wire.
(c) Check the DTCs that were output as a result of the malfunction simulation test. Then determine the malfunctioning area.
NEXT -- Continue to next step.
12. ADJUST, REPAIR AND REPLACE
NEXT -- Continue to next step.
13. CONFIRMATION TEST
NEXT -- END