How to Proceed With Troubleshooting
NETWORKING: CAN COMMUNICATION SYSTEM: HOW TO PROCEED WITH TROUBLESHOOTING
NOTICE:
* Refer to Diagnosis System for the DTCs for the CAN communication.
* Refer to troubleshooting of each system if DTCs regarding the CAN communication system are not output.
* After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notice before proceeding with work Service Precautions.
HINT
*: Use the Techstream.
1. VEHICLE BROUGHT TO WORKSHOP
NEXT -- Continue to next step.
2. CUSTOMER PROBLEM ANALYSIS
(a) Interview the customer and confirm the problem.
NEXT -- Continue to next step.
3. CHECK BATTERY
Standard Voltage:
11 to 14 V
HINT
If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.
NEXT -- Continue to next step.
4. CHECK AND CLEAR DTCS*
HINT
* CAN communication DTCs are stored 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 or the sensor itself also cause these DTCs to be stored.
* If a CAN communication wire connector is disconnected with the power switch on (IG), the ECUs of the corresponding system and related systems store a DTC.
NEXT -- Continue to next step.
5. CHECK DLC3 BRANCH LINE AND V1 BUS MAIN LINE (CANH - CANL)
NOTICE:
* Turn the power switch off before measuring the resistances between CAN main bus lines and between CAN bus branch lines.
* Turn the power switch off before inspecting CAN bus lines for a ground short.
* After the power 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 power switch, any other switches or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.
HINT
* Operating the power 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.
* Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.
(a) Turn the power switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
Result:
B -- GO TO OPEN IN CAN MAIN BUS LINE Open in CAN Main Bus Line
C -- GO TO SHORT IN CAN BUS LINES Check CAN Bus Lines for Short Circuit
A -- Continue to next step.
6. CHECK FOR SHORT TO GND IN V1 BUS (CANH, CANL - CG)
(a) Turn the power switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
Result:
B -- GO TO SHORT TO GND IN CAN BUS LINE Check CAN Bus Line for Short to GND
A -- Continue to next step.
7. CHECK FOR SHORT TO +B IN V1 BUS (CANH, CANL - BAT)
(a) Disconnect the cable from the negative (-) battery terminal.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
Result:
B -- GO TO SHORT TO +B IN CAN BUS LINE Check CAN Bus Line for Short To +B
A -- Continue to next step.
8. 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.
9. CHECK ECUS CONNECTED TO CAN BUS*
(a) Select "CAN Bus Check" from the screen on the Techstream Diagnosis System.
(b) Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.
Result:
NOTICE:
* The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs and sensors) are installed on the vehicle Diagnosis System.
* Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in communication stop mode.
* The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to the Techstream and its display are affected by signals output from other ECUs which have an open circuit in either of their CAN bus branch lines.)
HINT
* The ECUs connected to the V2 bus and power management bus are displayed on the screen by the power management control ECU.
* The ECUs connected to the CAN MS bus are displayed on the screen by the main body ECU.
B -- GO TO U1002 (Power Management1) U1002
C -- GO TO U1002 (Power Management2) U1002
D -- GO TO U1002 (MAIN BODY) U1002
E -- GO TO MAIN BODY ECU COMMUNICATION STOP MODE Main Body ECU Communication Stop Mode
F -- GO TO POWER MANAGEMENT CONTROL ECU COMMUNICATION STOP MODE Power Management Control ECU Communication Stop Mode
G -- GO TO COMMUNICATION STOP MODE TABLE Problem Symptoms Table
H -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
I -- GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Open in One Side of CAN Branch Line
A -- Continue to next step.
10. RECHECK DTC
HINT
* Sometimes CAN communication system DTCs are output, but all 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. Communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to DTC Combination Table for the CAN bus.
* The power management control ECU will store communication error DTCs when the ECUs connected to the V2 bus and power management bus cannot communicate, or if a network malfunction occurs.
* The main body ECU will store communication error DTCs when the ECUs connected to the CAN MS bus cannot communicate, or if a network malfunction occurs.
Result:
B -- GO TO U1002 (Power Management1) U1002
C -- GO TO U1002 (Power Management2) U1002
D -- GO TO U1002 (MAIN BODY) U1002
E -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
F -- GO TO DIAGNOSTIC TROUBLE CODE CHART CAN Communication System
A -- Continue to next step.
11. DTC COMBINATION TABLE
(a) Confirm the problem according to the combination of output DTCs regarding the CAN communication system Diagnosis System.
HINT
CAN communication system history DTCs may indicate the problem if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on "CAN Bus Check" of the Techstream.
NEXT -- Continue to next step.
12. CIRCUIT INSPECTION
NEXT -- Continue to next step.
13. IDENTIFICATION OF PROBLEM
NEXT -- Continue to next step.
14. REPAIR OR REPLACEMENT
NEXT -- Continue to next step.
15. CONFIRMATION TEST*
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