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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 the CAN bus main wire 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 bus main wire
  2. Short to +B in CAN bus branch wire
  3. Power management control ECU
  4. ECM
  5. Main body ECU
  6. Combination meter
  7. Skid control ECU (Brake booster with master cylinder)
  8. Steering angle sensor
  9. Yaw rate sensor
  10. Power steering ECU
  11. Center airbag sensor assembly
  12. Transmission control ECU
  13. Certification ECU
  14. Navigation ECU (Navigation receiver assembly)
  15. CAN No. 1 junction connector
  16. CAN No. 2 junction connector

WIRING DIAGRAM


C210552E02


C211041E04


INSPECTION PROCEDURE

NOTICE:
  1. Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
  2. Turn the power switch off before inspecting CAN bus wires 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 TO +B IN CAN BUS WIRE (CAN NO. 2 J/C)

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



    C210276E36

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



    C210421E04

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L61-6 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L61-14 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher

    Text in Illustration 
    *3
    		DLC3



NG
Go to step 3
OK


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

C210570E04

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

    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    		Connected to
    L95-5 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Center airbag sensor assembly
    L95-16 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L95-7 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Transmission control ECU
    L95-18 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L95-8 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Power management control ECU
    L95-19 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L95-9 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		ECM
    L95-20 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher


    Text in Illustration 
    *1
    		Front view of wire harness connector
    (to CAN No. 2 Junction Connector)
    		*2
    		DLC3
    *3
    		to Center Airbag Sensor Assembly
    		*4
    		to Transmission Control ECU
    *5
    		to Power Management Control ECU
    		*6
    		to ECM

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



B
Go to step 4
A

REPLACE CAN NO. 2 JUNCTION CONNECTOR 

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

  1. Disconnect the CAN No. 1 junction connector.


C210570E03


Text in Illustration 
*1
Front view of wire harness connector
(to CAN No. 1 Junction Connector)
*2
DLC3
*3
to Combination Meter
*4
to Steering Angle Sensor
*5
to Main Body ECU
*6
to Power Steering ECU
*7
to DLC3
*8
to Navigation ECU
*9
to CAN No. 2 Junction Connector
*10
to Yaw Rate Sensor
*11
to Certification ECU
*12
to Skid Control ECU

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

    Standard Resistance:

    Tester Connection
    		Condition
    		Specified Condition
    		Connected to
    L94-1 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Combination meter
    L94-12 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-2 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Steering angle sensor
    L94-13 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-3 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Main body ECU
    L94-14 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-4 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Power steering ECU
    L94-15 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-5 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		DLC3
    L94-16 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-6 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Navigation ECU
    L94-17 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-7 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		CAN No. 2 junction connector
    L94-18 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-8 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Yaw rate sensor
    L94-19 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-9 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Certification ECU
    L94-20 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L94-10 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    		Skid control ECU
    L94-21 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher

Result:
Result
Proceed to
OK
A
NG (to DLC3 branch wire)
B
NG (to CAN No. 2 J/C main wire)
C
NG (to ECU or sensor wire)
D



B
REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO DLC3

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

D
Go to step 4
A

REPLACE CAN NO. 1 JUNCTION CONNECTOR 

4.CHECK FOR SHORT TO +B IN CAN BUS WIRE (ECU, SENSOR)

  1. Reconnect the CAN No. 1 Junction connector and CAN No. 2 junction connector.

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

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



    C210421E03

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    L61-6 (CANH) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher
    L61-14 (CANL) - L61-16 (BAT)
    		Cable disconnected from negative (-) battery terminal
    		6 kΩ or higher

    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 OR SENSOR WIRE OR CONNECTOR
OK

REPLACE CORRESPONDING ECU OR SENSOR