CAN COMMUNICATION SYSTEM > Check CAN Bus Line for Short to +B (LHD Models)

for Preparation Click here


DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when no resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of the DLC3.

Symptom
Trouble Area
No resistance exists between terminals 6 (CANH) and 16 (BAT) or 14 (CANL) and 16 (BAT) of DLC3.
  1. Short to +B in CAN main bus line
  2. Short to +B 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. After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work (Click here).
  2. Turn the power switch off before measuring the resistances between CAN main bus lines and between CAN branch lines.
  3. Turn the power switch off before inspecting CAN bus lines for a ground short.
  4. After the power switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
  5. 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 TO +B IN CAN BUS LINE (CAN NO. 2 J/C)

  1. Disconnect the cable from the negative (-) auxiliary battery terminal.



    C214799E07

  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
    		Condition
    		Specified Condition
    		Connected to
    H104-1 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		CAN No. 1 junction connector
    H104-2 (CANL) - H44-16 (BAT)
    H104-4 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		CAN No. 3 junction connector
    H104-5 (CANL) - H44-16 (BAT)
    H104-7 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		DLC3
    H104-8 (CANL) - H44-16 (BAT)
    H104-10 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Power steering ECU assembly
    H104-11 (CANL) - H44-16 (BAT)
    H104-13 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Navigation ECU
    H104-14 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *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
    *e
    		to Power Steering ECU Assembly
    *f
    		to Navigation ECU

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (DLC3 branch line)
    		B
    NG (CAN No. 1 junction connector main line)
    		C
    NG (CAN No. 3 junction connector main line)
    		D
    NG (ECU or sensor wire)
    		E



B
REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3

C
Go to step 3

D
Go to step 5

E
Go to step 7
A


2.CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 2 J/C)


    C214799E08

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

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    		Connected to
    H105-3 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Steering angle sensor (Spiral cable with sensor sub-assembly)
    H105-2 (CANL) - H44-16 (BAT)
    H105-6 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Certification ECU (Smart key ECU assembly)
    H105-5 (CANL) - H44-16 (BAT)
    H105-9 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Airbag sensor assembly
    H105-8 (CANL) - H44-16 (BAT)
    H105-12 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Yaw rate and acceleration sensor
    H105-11 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *a
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    *b
    		to Steering Angle Sensor (Spiral Cable with Sensor Sub-assembly)
    *c
    		to Certification ECU (Smart Key ECU Assembly)
    *d
    		to Airbag Sensor Assembly
    *e
    		to Yaw Rate and Acceleration Sensor

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (ECU or sensor wire)
    		B



B
Go to step 7
A

REPLACE CAN NO. 2 JUNCTION CONNECTOR 

3.CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 1 J/C)


    C235205E01

  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
    		Condition
    		Specified Condition
    		Connected to
    H112-5 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Main body ECU (Multiplex network body ECU)
    H112-11 (CANL) - H44-16 (BAT)
    H112-6 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		CAN No. 2 junction connector
    H112-12 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to Main Body ECU (Multiplex Network Body ECU)
    *c
    		to CAN No. 2 Junction Connector

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (CAN No. 2 junction connector main line)
    		B
    NG (Main body ECU branch line)
    		C



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

C
Go to step 7
A


4.CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 1 J/C)


    C235205E02

  1. Disconnect the engine room main 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
    		Condition
    		Specified Condition
    		Connected to
    A57-1 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		ECM
    A57-7 (CANL) - H44-16 (BAT)
    A57-2 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Skid Control ECU (Brake Booster with Master Cylinder Assembly)
    A57-8 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *a
    		Front view of wire harness connector
    (to CAN No. 1 Junction Connector)
    *b
    		to ECM
    *c
    		to Skid Control ECU

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (ECU or sensor wire)
    		B



B
Go to step 7
A

REPLACE CAN NO. 1 JUNCTION CONNECTOR 

5.CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 3 J/C)


    C235205E03

  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
    		Condition
    		Specified Condition
    		Connected to
    H113-4 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Power management control ECU
    H113-10 (CANL) - H44-16 (BAT)
    H113-5 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		CAN No. 2 junction connector
    H113-11 (CANL) - H44-16 (BAT)
    H113-6 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Combination meter assembly
    H113-12 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to Power Management Control ECU
    *c
    		to CAN No. 2 Junction Connector
    *d
    		to Combination Meter Assembly

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (CAN No. 2 junction connector main line)
    		B
    NG (ECU or sensor wire)
    		C



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

C
Go to step 7
A


6.CHECK FOR SHORT TO +B IN CAN BUS LINE (CAN NO. 3 J/C)


    C235205E04

  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
    		Condition
    		Specified Condition
    		Connected to
    A58-1 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    		Transmission control ECU
    A58-7 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3
    *a
    		Front view of wire harness connector
    (to CAN No. 3 Junction Connector)
    *b
    		to Transmission Control ECU Assembly

    Result:
    Result
    		Proceed to
    OK
    		A
    NG (Transmission control ECU assembly branch line)
    		B



B
Go to step 7
A

REPLACE CAN NO. 3 JUNCTION CONNECTOR 

7.CHECK FOR SHORT TO +B IN CONNECTED COMPONENT (ECU, SENSOR)

  1. Reconnect all wire harness connectors (CAN J/C1, CAN J/C2 and CAN J/C3).

  1. Disconnect the ECU or sensor connected to the CAN bus line that is shorted to +B.

    HINT:
    If the ECU or sensor has multiple connectors, disconnect the connector that includes the CAN bus lines. To determine the ECU or sensor that is connected to the shorted bus line, refer to the terminals of ECU tables (Click here).



    C210421E25

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    H44-6 (CANH) - H44-16 (BAT)
    		Cable disconnected from negative (-) auxiliary battery terminal
    		6 kΩ or higher
    H44-14 (CANL) - H44-16 (BAT)

    Text in Illustration 
    *1
    		DLC3

    HINT:
    If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).



NG
REPAIR OR REPLACE CORRESPONDING ECU/SENSOR WIRE OR CONNECTOR
OK

REPLACE CORRESPONDING ECU OR SENSOR