Check CAN Bus Lines for Short Circuit

NETWORKING: CAN COMMUNICATION SYSTEM: Check CAN Bus Lines for Short Circuit
- Check CAN Bus Lines for Short Circuit

DESCRIPTION

The CAN bus wires are considered to be shorted when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ohms.

WIRING DIAGRAM

INSPECTION PROCEDURE

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.

PROCEDURE

1. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C)

(a) Turn the engine switch off.

(b) Disconnect the CAN No. 1 J/C wire harness connector.

Text in Illustration

Result:

B -- CHECK FOR SHORT IN CAN BUS WIRES (ECM MAIN BUS WIRE)

C -- CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 2 J/C)

D -- REPAIR OR REPLACE DLC3 BRANCH WIRE OR CONNECTOR
A -- Continue to next step.

2. CHECK FOR SHORT IN CAN BUS WIRES (SKID CONTROL ECU BRANCH WIRE)

(a) Disconnect the brake actuator assembly (skid control ECU) connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (SKID CONTROL ECU)
OK -- Continue to next step.

3. CHECK FOR SHORT IN CAN BUS WIRES (STEERING ANGLE SENSOR BRANCH WIRE)

(a) Disconnect the steering angle sensor connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (STEERING ANGLE SENSOR)
OK -- Continue to next step.

4. CHECK FOR SHORT IN CAN BUS WIRES (YAW RATE SENSOR BRANCH WIRE)

(a) Disconnect the yaw rate sensor connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (YAW RATE SENSOR)
OK -- Continue to next step.

5. CHECK FOR SHORT IN CAN BUS WIRES (CENTER AIRBAG SENSOR BRANCH WIRE)

(a) Disconnect the center airbag sensor connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (CENTER AIRBAG SENSOR)
OK -- Continue to next step.

6. CHECK FOR SHORT IN CAN BUS WIRES (DISTANCE CONTROL ECU BRANCH WIRE)

HINT
For vehicles without the dynamic radar cruise control system, go to the next step.

(a) Disconnect the distance control ECU connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (DISTANCE CONTROL ECU)
OK -- Continue to next step.

7. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 1 J/C)

(a) Reconnect the CAN No. 1 J/C wire harness connector.

(b) Measure the resistance according to the value(s) in the table below.

NOTICE:
* The resistance must be measured after the CAN No. 1 J/C wire harness connector is reconnected.
* The resistance must be measured after the CAN No. 1 J/C branch wire connected ECU and sensor connector are disconnected.

Standard Resistance:

Text in Illustration

NG -- REPLACE CAN NO. 1 J/C
OK -- Continue to next step.

8. CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)

(a) Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.

Text in Illustration

(b) While observing the resistance value shown on the ohmmeter, reconnect the each ECU and sensor connector until the resistance becomes abnormal (Below 54 Ohms).

(c) If the resistance becomes abnormal when an ECU connector is reconnected, there may be a short in the ECU.

HINT
If the resistance becomes abnormal when an ECU connector is reconnected, there may be a short in the ECU.

NEXT -- REPLACE CORRESPONDING ECU OR SENSOR

9. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 2 J/C)

(a) Reconnect the CAN No. 1 J/C wire harness connector.

(b) Disconnect the CAN No. 2 J/C wire harness connector.

Text in Illustration

Result:

B -- CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 3 J/C)

C -- CHECK FOR SHORT IN CAN BUS WIRES (GATEWAY ECU MAIN BUS WIRE)
A -- Continue to next step.

10. CHECK FOR SHORT IN CAN BUS WIRES (POWER STEERING ECU BRANCH WIRE)

(a) Disconnect the power steering ECU connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (POWER STEERING ECU)
OK -- Continue to next step.

11. CHECK FOR SHORT IN CAN BUS WIRES (DISPLAY AND NAVIGATION MODULE DISPLAY BRANCH WIRE)

HINT
For vehicles without multi-display, go to the next step.

(a) Disconnect the display and navigation module display connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (DISPLAY AND NAVIGATION MODULE DISPLAY)
OK -- Continue to next step.

12. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 2 J/C)

(a) Reconnect the CAN No. 2 J/C wire harness connector.

(b) Measure the resistance according to the value(s) in the table below.

NOTICE:
* The resistance must be measured after the CAN No. 2 J/C wire harness connector is reconnected.
* The resistance must be measured after the power steering ECU and navigation ECU connector are disconnected.

Standard Resistance:

Text in Illustration

Result:

B -- REPLACE POWER STEERING ECU ASSEMBLY

C -- REPLACE CAN NO. 2 J/C
A -- Continue to next step.

13. CHECK FOR SHORT IN CAN BUS WIRES (POWER STEERING ECU)

(a) Reconnected the power steering ECU connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPLACE POWER STEERING ECU ASSEMBLY

OK -- REPLACE DISPLAY AND NAVIGATION MODULE DISPLAY

14. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 3 J/C)

(a) Reconnect the CAN No. 1 J/C wire harness connector.

(b) Disconnect the CAN No. 3 J/C wire harness connector.

Text in Illustration

Result:

B -- REPLACE CAN NO. 3 J/C

C -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 1 J/C - CAN NO. 3 J/C)

D -- REPAIR OR REPLACE CAN BUS MAIN WIRE (CAN NO. 2 J/C - CAN NO. 3 J/C)
A -- Continue to next step.

15. CHECK FOR SHORT IN CAN BUS WIRES (SEAT BELT CONTROL ECU BRANCH WIRE)

(a) Disconnect the seat belt control ECU connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (SEAT BELT CONTROL ECU)
OK -- Continue to next step.

16. CHECK FOR SHORT IN CAN BUS WIRES (CAN NO. 3 J/C)

(a) Reconnect the CAN No. 3 J/C wire harness connector.

(b) Measure the resistance according to the value(s) in the table below.

NOTICE:
* The resistance must be measured after the CAN No. 3 J/C wire harness connector is reconnected.
* The resistance must be measured after the seat belt control ECU connector is disconnected.

Standard Resistance:

Text in Illustration

NG -- REPLACE CAN NO. 3 J/C

OK -- REPLACE SEAT BELT CONTROL ECU

17. CHECK FOR SHORT IN CAN BUS WIRES (ECM MAIN BUS WIRE)

(a) Reconnect the CAN No. 1 J/C wire harness connector.

(b) Disconnect the ECM connector.

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NG -- REPAIR OR REPLACE CAN BUS MAIN WIRE (ECM MAIN BUS LINE)

OK -- REPLACE ECM

18. CHECK FOR SHORT IN CAN BUS WIRES (GATEWAY ECU MAIN BUS WIRE)

(a) Reconnect the CAN No. 2 J/C wire harness connector.

(b) Disconnect the gateway ECU connector.

Text in Illustration

NG -- REPAIR OR REPLACE CAN BUS MAIN WIRE (GATEWAY ECU MAIN BUS LINE)

OK -- REPLACE GATEWAY ECU