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, U0101, U0122, U0123, U0124, U0126, U0129, U0146, U0151 and U1101.
* Refer to troubleshooting of each system if DTCs regarding the CAN communication system are not output.
HINT
*: Use the Techstream
1. INSPECT BATTERY VOLTAGE
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.
2. 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 can cause these DTCs to be stored.
* If a CAN communication wire connector is disconnected with the engine switch on (IG), the ECUs of the corresponding system and related systems store a DTC.
NEXT -- Continue to next step.
3. CHECK DLC3 BRANCH WIRE AND CAN BUS CIRCUIT MAIN WIRE (CANH - CANL)
NOTICE:
* Turn the engine switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
* Turn the engine switch off before inspecting CAN bus wires for a ground short.
* After the engine 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 engine 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 engine 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 engine switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
B -- GO TO OPEN IN CAN MAIN LINE Open in CAN Main Bus Line
C -- GO TO CHECK CAN BUS LINES FOR SHORT CIRCUIT Check CAN Bus Lines for Short Circuit
A -- Continue to next step.
4. CHECK FOR SHORT TO GND IN CAN BUS (CANH, CANL - CG)
(a) Turn the engine switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Text in Illustration
NG -- GO TO CHECK CAN BUS LINE FOR SHORT TO GND Check CAN Bus Line for Short to GND
OK -- Continue to next step.
5. CHECK FOR SHORT TO +B IN CAN 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
NG -- GO TO CHECK CAN BUS LINE FOR SHORT TO +B Check CAN Bus Line for Short to +B
OK -- Continue to next step.
6. 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.
7. CHECK ECUS CONNECTED TO CAN BUS*
(a) Using the Techstream, select "CAN Bus Check" from the "System Select".
(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.
* Non-installed ECUs or sensors are not displayed. Do not mistake them for being in communication stop mode.
* Techstream display is 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 Symptom Related Diagnostic Procedures
C -- GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Open in One Side of CAN Branch Line
A -- Continue to next step.
8. DTC COMBINATION TABLE
(a) Confirm trouble according to the combination of output DTCs regarding the CAN communication system 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. Communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to the DTC combination table for the CAN bus.
NEXT -- Continue to next step.
9. CIRCUIT INSPECTION
NEXT -- Continue to next step.
10. IDENTIFICATION OF PROBLEM
NEXT -- Continue to next step.
11. REPAIR OR REPLACE
NEXT -- Continue to next step.
12. CONFIRMATION TEST
NEXT -- END