How to Proceed With Troubleshooting

CAN COMMUNICATION SYSTEM:

HOW TO PROCEED WITH TROUBLESHOOTING

1. INSPECT BATTERY VOLTAGE
Standard voltage:
11 - 14 V

HINT: If the voltage is below 11 V, recharge or replace the battery before proceeding.

NEXT -- Continue to next step.
2. CHECK AND CLEAR DTCS

NOTE: DTCs for the CAN communication system are as follows: U0073, U0123, U0124 and U0126.

HINT:
- CAN communication DTCs are output 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 output.
- If a CAN communication wire connector is disconnected with the ignition switch ON, the ECUs of the corresponding system and related systems record a DTC.

NEXT -- Continue to next step.
3. CHECK FOR INSTALLED SYSTEMS (ECUS & SENSORS) THAT ADOPT CAN COMMUNICATION
(a) Check the adopted brake control system.
NEXT -- Continue to next step.
4. CHECK DLC3 BRANCH WIRE AND CAN NO. 1 BUS CIRCUIT MAIN WIRE (CANH - CANL)

NOTE: Turn the ignition switch off before measuring the resistances of the CAN main wire and the CAN branch wire.





(a) Turn the ignition switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





Result (w/ VSC):





Result (w/o VSC):





B -- GO TO CAN MAIN WIRE FOR DISCONNECTION
C -- GO TO CHECK CAN BUS LINES FOR SHORT CIRCUIT
D -- GO TO "ECM COMMUNICATION STOP MODE"
A -- Continue to next step.
5. CHECK FOR SHORT TO GND IN CAN BUS (CANH, CANL - CG)





(a) Measure the resistance according to the value(s) in the table below.
Standard resistance:





Result:





B -- GO TO CHECK CAN BUS LINE FOR SHORT TO GND
C -- GO TO "ECM COMMUNICATION STOP MODE"
A -- Continue to next step.
6. CHECK FOR SHORT TO +B IN CAN BUS (CANH, CANL - BAT)





(a) Measure the resistance according to the value(s) in the table below.
Standard resistance:





Result:





B -- GO TO CHECK CAN BUS LINE FOR SHORT TO +B
C -- GO TO "ECM COMMUNICATION STOP MODE"
A -- Continue to next step.
7. CHECK WITH TECHSTREAM
(a) Using Techstream, check for ECUs and sensors connected to CAN bus (Diagnosis System).
(b) Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.

Result





NOTE: Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in the communication stop mode.

HINT: The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to Techstream and the tester display are 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"
C -- GO TO "OPEN IN ONE SIDE OF CAN BRANCH WIRE"
D -- GO TO "ECM COMMUNICATION STOP MODE".
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).
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