CAN COMMUNICATION SYSTEM > Check CAN Bus Lines for Short Circuit (LHD Models)

for Preparation Click here


DESCRIPTION

There may be a short circuit between the V1 bus main lines and/or CAN branch lines when the resistance between terminals 6 (CANH) and 14 (CANL) of the DLC3 is below 54 Ω.

Symptom
Trouble Area
Resistance between terminals 6 (CANH) and 14 (CANL) of DLC3 is below 54 Ω.
  1. Short in CAN main bus line
  2. Short in CAN branch line
  3. Power management control ECU
  4. ECM
  5. Main body ECU (Multiplex network body ECU)
  6. Combination meter assembly
  7. Skid control ECU (Brake booster with master cylinder assembly)
  8. Steering angle sensor (Spiral cable with sensor sub-assembly)
  9. Yaw rate and acceleration sensor
  10. Power steering ECU assembly
  11. Airbag sensor assembly
  12. Transmission control ECU assembly
  13. Certification ECU (Smart key ECU assembly)
  14. Navigation ECU (Display and navigation module display)*1
  15. Navigation ECU (Navigation computer sub-assembly)*2
  16. CAN No. 1 junction connector
  17. CAN No. 2 junction connector
  18. CAN No. 3 junction connector
*1: w/ Navigation system (for DVD)
*2: w/ Navigation system (for HDD)

WIRING DIAGRAM


C236218E03


C237146E01


INSPECTION PROCEDURE

NOTICE:
  1. Turn the power switch off before measuring the resistances between CAN main bus lines and between CAN branch lines.
  2. Turn the power switch off before inspecting CAN bus lines for a ground short.
  3. After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
  4. 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:
  1. 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.
  2. 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.

1.CHECK FOR SHORT IN CAN BUS LINES (ECM)

  1. Turn the power switch off.



    C188240E05

  1. Disconnect the ECM connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A60-13 (CANH) - A60-5 (CANL)
    		Power switch off
    		108 to 132 Ω

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to ECM)



NG
Go to step 2
OK

REPLACE ECM (Click here)  

2.CHECK FOR SHORT IN CAN BUS LINES (COMBINATION METER ASSEMBLY)

  1. Reconnect the ECM connector.



    C188241E76

  1. Disconnect the combination meter assembly connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H19-32 (CANH) - H19-31 (CANL)
    		Power switch off
    		108 to 132 Ω

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to Combination Meter Assembly)



NG
Go to step 3
OK

REPLACE COMBINATION METER ASSEMBLY (Click here)  

3.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C)

  1. Reconnect the combination meter assembly connector.



    C214272E65

  1. Disconnect the wire harness connector from the CAN No. 2 junction connector rear side.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Connected to
    H104-1 (CANH) - H104-2 (CANL)
    		Power switch off
    		108 to 132 Ω
    		CAN No. 1 junction connector
    H104-4 (CANH) - H104-5 (CANL)
    		Power switch off
    		108 to 132 Ω
    		CAN No. 3 junction connector
    H104-7 (CANH) - H104-8 (CANL)
    		Power switch off
    		1 MΩ or higher
    		DLC3

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to CAN No. 1 Junction Connector
    *c
    		to CAN No. 3 Junction Connector
    *d
    		to DLC3

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (CAN No. 1 J/C main line)
    		B
    NG (CAN No. 3 J/C main line)
    		C
    NG (DLC3 branch line)
    		D



B
Go to step 12

C
Go to step 18

D
REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3
A


4.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - POWER STEERING ECU ASSEMBLY)

  1. Disconnect the power steering ECU assembly connector.



    C214272E66

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H104-10 (CANH) - H104-11 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Power Steering ECU Assembly



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - POWER STEERING ECU ASSEMBLY)
OK


5.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - NAVIGATION ECU)

HINT:
For vehicles without the navigation system, go to the next step.

  1. Disconnect the navigation ECU connector.



    C214272E67

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H104-13 (CANH) - H104-14 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Navigation ECU



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - NAVIGATION ECU)
OK


6.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - YAW RATE AND ACCELERATION SENSOR)

  1. Disconnect the CAN No. 2 junction connector front side.

  1. Disconnect the yaw rate and acceleration sensor connector.



    C214272E68

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

    Standard Resistance:
    Tester Connection
    		 Switch Condition
    		Specified Condition
    H105-12 (CANH) - H105-11 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Yaw Rate and Acceleration Sensor



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - YAW RATE AND ACCELERATION SENSOR)
OK


7.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - STEERING ANGLE SENSOR)

  1. Disconnect the steering angle sensor connector.



    C214272E69

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H105-3 (CANH) - H105-2 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Steering Angle Sensor



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - STEERING ANGLE SENSOR)
OK


8.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - AIRBAG SENSOR ASSEMBLY)

  1. Disconnect the airbag sensor assembly connector.



    C214272E70

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H105-9 (CANH) - H105-8 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Airbag Sensor Assembly



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - AIRBAG SENSOR ASSEMBLY)
OK


9.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - CERTIFICATION ECU)

  1. Disconnect the certification ECU (smart key ECU assembly) connector.



    C214272E71

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H105-6 (CANH) - H105-5 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Certification ECU (Smart Key ECU Assembly)



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 2 J/C - CERTIFICATION ECU)
OK


10.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C)

  1. Reconnect the wire harness connector to the CAN No. 2 junction connector front side and rear side.



    C210421E27

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H44-6 (CANH) - H44-14 (CANL)
    		Power switch off
    		54 to 69 Ω

    Text in Illustration 
    *1
    		DLC3

    NOTICE:
    1. The resistance must be measured after the main line connected ECUs (ECM and combination meter assembly), CAN No. 1 junction connector, CAN No. 2 junction connector and CAN No. 3 junction connector are reconnected.
    2. The resistance must be measured after the CAN No. 2 junction connector branch line connected ECU and sensor connectors are disconnected.



NG
REPLACE CAN NO. 2 JUNCTION CONNECTOR
OK


Go to step 12

11.CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)


    C210421E27

  1. Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
    Text in Illustration 
    *1
    		DLC3

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

    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 

12.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 2 J/C - CAN NO. 1 J/C)

  1. Reconnect the wire harness connector to the CAN No. 2 junction connector rear side.



    C234634E01

  1. Disconnect the instrument panel wire from the CAN No. 1 junction connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H112-6 (CANH) - H112-12 (CANL)
    		Power switch off
    		108 to 132 Ω

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to CAN No. 2 Junction Connector



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 1 J/C)
OK


13.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C - MAIN BODY ECU)

  1. Disconnect the main body ECU (multiplex network body ECU) connector.



    C234634E02

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H112-5 (CANH) - H112-11 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to Main Body ECU



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 1 J/C - MAIN BODY ECU)
OK


14.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C - SKID CONTROL ECU)

  1. Disconnect the engine room main wire from the CAN No. 1 junction connector.

  1. Disconnect the skid control ECU (brake booster with master cylinder assembly) connector.



    C234634E22

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A57-2 (CANH) - A57-8 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to Skid Control ECU



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 1 J/C - SKID CONTROL ECU)
OK


15.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 1 J/C - ECM)


    C234634E04

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A57-1 (CANH) - A57-7 (CANL)
    		Power switch off
    		108 to 132 Ω

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to ECM



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 1 J/C - ECM)
OK


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

  1. Reconnect the instrument panel wire and engine room main wire to the CAN No. 1 junction connector.



    C210421E27

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H44-6 (CANH) - H44-14 (CANL)
    		Power switch off
    		54 to 69 Ω

    Text in Illustration 
    *1
    		DLC3

    NOTICE:
    1. The resistance must be measured after the main line connected ECUs (ECM and combination meter assembly), CAN No. 1 junction connector, CAN No. 2 junction connector and CAN No. 3 junction connector are reconnected.
    2. The resistance must be measured after the CAN No. 1 junction connector branch line connected ECU are disconnected.



NG
REPLACE CAN NO. 1 JUNCTION CONNECTOR
OK


17.CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)


    C210421E27

  1. Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
    Text in Illustration 
    *1
    		DLC3

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

    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 

18.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C - CAN NO. 2 J/C)

  1. Reconnect the wire harness connector to the CAN No. 2 junction connector rear side.



    C234634E05

  1. Disconnect the instrument panel wire from the CAN No. 3 junction connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Connected to
    H113-5 (CANH) - H113-11 (CANL)
    		Power switch off
    		108 to 132 Ω
    		CAN No. 2 junction connector

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to CAN No. 2 Junction Connector



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 2 J/C - CAN NO. 3 J/C)
OK


19.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C - COMBINATION METER ASSEMBLY)


    C234634E06

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    		Connected to
    H113-6 (CANH) - H113-12 (CANL)
    		Power switch off
    		108 to 132 Ω
    		Combination meter assembly

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to Combination Meter Assembly



NG
REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (CAN NO. 3 J/C - COMBINATION METER ASSEMBLY)
OK


20.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C - POWER MANAGEMENT CONTROL ECU)

  1. Disconnect the power management control ECU connector.



    C234634E07

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H113-4 (CANH) - H113-10 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to Power Management Control ECU



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 3 J/C - POWER MANAGEMENT CONTROL ECU)
OK


21.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C - TRANSMISSION CONTROL ECU ASSEMBLY)

  1. Disconnect the transmission control ECU assembly connector.



    C234634E08

  1. Disconnect the engine room main wire from the CAN No. 3 junction connector.

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A58-1 (CANH) - A58-7 (CANL)
    		Power switch off
    		1 MΩ or higher

    Text in Illustration 
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to Transmission Control ECU Assembly



NG
REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (CAN NO. 3 J/C - TRANSMISSION CONTROL ECU ASSEMBLY)
OK


22.CHECK FOR SHORT IN CAN BUS LINES (CAN NO. 3 J/C)

  1. Reconnect the instrument panel wire and engine room main wire to the CAN No. 3 junction connector.



    C210421E27

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

    Standard Resistance:
    Tester Connection
    		Switch Condition
    		Specified Condition
    H44-6 (CANH) - H44-14 (CANL)
    		Power switch off
    		54 to 69 Ω

    Text in Illustration 
    *1
    		DLC3

    NOTICE:
    1. The resistance must be measured after the main line connected ECUs (ECM and combination meter assembly), CAN No. 1 junction connector, CAN No. 2 junction connector and CAN No. 3 junction connector are reconnected.
    2. The resistance must be measured after the CAN No. 3 junction connector branch line connected ECU are disconnected.



NG
REPLACE CAN NO. 3 JUNCTION CONNECTOR
OK


23.CHECK FOR SHORT IN CONNECTED COMPONENT (ECU, SENSOR)


    C210421E27

  1. Connect the probes of an ohmmeter to terminals 6 (CANH) and 14 (CANL) of the DLC3.
    Text in Illustration 
    *1
    		DLC3

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

    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