CAN COMMUNICATION SYSTEM Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus wire and/or CAN branch wire when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 18 (CA4H) and 17 (CA4L) of central gateway ECU (network gateway ECU) is below 54 Ω.

  • Short in CAN main bus wire

  • Short in CAN branch wire

  • Central gateway ECU (network gateway ECU)

  • ECM

  • Combination meter assembly

  • Air conditioning amplifier assembly

  • Power steering ECU assembly

  • Certification ECU (smart key ECU assembly)

  • Airbag ECU assembly

  • Main body ECU (multiplex network body ECU)

  • Brake booster with master cylinder assembly (skid control ECU)

  • Steering angle sensor (spiral with sensor cable sub-assembly)

  • Parking brake ECU assembly

  • Meter mirror sub-assembly*1

  • Stereo component equalizer assembly*2

  • Headlight ECU sub-assembly LH

  • Hybrid vehicle control ECU

  • No. 2 CAN junction connector

  • No. 3 CAN junction connector
*1: w/ Headup Display
*2: w/ ASC System

WIRING DIAGRAM


  1. for LHD:

    B002IVRE02
    B002IG0E06

  2. for RHD:

    B002K89E02
    B002K9CE04

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

Note


  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

    Click here

  • Before measuring the resistance of the CAN bus, turn the power switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • 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

  • Some parts must be initialized and set when replacing or removing and installing parts.

    Click here

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

    DTC check procedure: Turn the power switch on (IG) and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.

  • After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

    Click here

  • Before replacing the certification ECU (smart key ECU assembly), refer to Service Bulletin.

  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

Tech Tips


  • Operating the power switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • 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 (NO. 2 CAN JUNCTION CONNECTOR)


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

    2. Disconnect the No. 2 CAN junction connector.

      B002JXNC93
      *a

      Front view of wire harness connector

      (to No. 2 CAN Junction Connector)

      		 *b

      • to Hybrid Vehicle Control ECU (for LHD)

      • to Air Conditioning Amplifier Assembly (for RHD)
      *c

      • to Stereo Component Equalizer Assembly (for LHD with ASC System)

      • to Power Steering ECU Assembly (for RHD)

      		 *d to Central Gateway ECU (Network Gateway ECU)
      *e to No. 3 CAN Junction Connector *f to Certification ECU (Smart Key ECU Assembly)
      *g to Combination Meter Assembly *h

      • to Steering Angle Sensor (Spiral with Sensor Cable Sub-assembly) (for RHD)

      • to Meter Mirror Sub-assembly (for LHD with Headup Display)
      *i to Airbag ECU Assembly - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I93-1 (CANH) - I93-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Hybrid vehicle control ECU*1

      • Air conditioning amplifier assembly*2
      I93-2 (CANH) - I93-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Stereo component equalizer assembly*3

      • Power steering ECU assembly*2
      I93-4 (CANH) - I93-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Central gateway ECU (network gateway ECU)
      I93-5 (CANH) - I93-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 3 CAN junction connector
      I93-6 (CANH) - I93-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Certification ECU (smart key ECU assembly)
      I93-7 (CANH) - I93-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω Combination meter assembly
      I93-9 (CANH) - I93-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Steering angle sensor (spiral with sensor cable sub-assembly)*2

      • Meter mirror sub-assembly*4
      I93-10 (CANH) - I93-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Airbag ECU assembly
      *1: for LHD
      *2: for RHD
      *3: for LHD with ASC System
      *4: for LHD with Headup Display
      Result
      Result Proceed to
      OK A
      NG (Central gateway ECU [network gateway ECU] CAN branch wire) B
      NG (No. 3 CAN junction connector CAN main wire) C
      NG (Wire to ECU or sensor) D

    A

    REPLACE NO. 2 CAN JUNCTION CONNECTOR

    C

    CONNECT CONNECTOR Click here

    D

    GO TO STEP 8 Click here

    B

  2. CONNECT CONNECTOR


    1. Reconnect the I93 No. 2 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT

  3. CHECK FOR SHORT IN CAN BUS WIRES (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 2 CAN JUNCTION CONNECTOR)


    1. Disconnect the central gateway ECU (network gateway ECU) connector.

    2. B002JICC55
      *a

      Front view of wire harness connector

      (to Central Gateway ECU [Network Gateway ECU])

      Disconnect the No. 2 CAN junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-18 (CA4H) - I164-17 (CA4L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) fro LHD: Click here
    REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU) fro RHD: Click here

    NG

    REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (CENTRAL GATEWAY ECU [NETWORK GATEWAY ECU] - NO. 2 CAN JUNCTION CONNECTOR)

  4. CONNECT CONNECTOR


    1. Reconnect the I93 No. 2 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK FOR SHORT IN CAN BUS WIRES (NO. 3 CAN JUNCTION CONNECTOR)


    1. Disconnect the No. 3 CAN junction connector.

      B002JXNC89
      *a

      Front view of wire harness connector

      (to No. 3 CAN Junction Connector)

      		 *b to Air Conditioning Amplifier Assembly (for LHD)
      *c

      • to Power Steering ECU Assembly (for LHD)

      • to Stereo Component Equalizer Assembly (for RHD with ASC System)

      		 *d

      • to Parking Brake ECU Assembly (for RHD)

      • to Headlight ECU Sub-assembly LH (for LHD)
      *e to Main Body ECU (Multiplex Network Gateway ECU) *f to Meter Mirror Sub-assembly (for RHD with Headup Display)
      *g to No. 2 CAN Junction Connector *h to ECM
      *i to Brake Booster with Master Cylinder Assembly (Skid Control ECU) *j

      • to Steering Angle Sensor (Spiral with Sensor Cable Sub-assembly) (for LHD)

      • to Hybrid Vehicle Control ECU (for RHD)
      *k

      • to Headlight ECU Sub-assembly LH (for RHD)

      • to Parking Brake ECU Assembly (for LHD)

      		 - -

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

      Standard Resistance
      Tester Connection Condition Specified Condition Connected to
      I94-1 (CANH) - I94-11 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Air conditioning amplifier assembly*1
      I94-2 (CANH) - I94-12 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Power steering ECU assembly*1

      • Stereo component equalizer assembly*2
      I94-3 (CANH) - I94-13 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Headlight ECU sub-assembly LH*1

      • Parking brake ECU assembly*2
      I94-4 (CANH) - I94-14 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Main body ECU (multiplex network gateway ECU)
      I94-5 (CANH) - I94-15 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Meter mirror sub-assembly*3
      I94-6 (CANH) - I94-16 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω No. 2 CAN junction connector
      I94-7 (CANH) - I94-17 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω ECM
      I94-8 (CANH) - I94-18 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher Brake booster with master cylinder assembly (skid control ECU)
      I94-9 (CANH) - I94-19 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Steering angle sensor (spiral with sensor cable sub-assembly)*1

      • Hybrid vehicle control ECU*2
      I94-10 (CANH) - I94-20 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher

      • Parking brake ECU assembly*1

      • Headlight ECU sub-assembly LH*2
      *1: for LHD
      *2: for RHD
      *3: for RHD with Headup Display
      Result
      Result Proceed to
      OK A
      NG (ECM CAN main wire) B
      NG (No. 2 CAN junction connector CAN main wire) C
      NG (Wire to ECU or sensor) D

    A

    REPLACE NO. 3 CAN JUNCTION CONNECTOR

    C

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

    D

    CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR) Click here

    B

  6. CONNECT CONNECTOR


    1. Reconnect the I94 No. 3 CAN junction connector.

      Result
      Proceed to
      NEXT

    NEXT

  7. CHECK FOR SHORT IN CAN BUS WIRES (ECM - NO. 3 CAN JUNCTION CONNECTOR)


    1. B002IHWC01
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A35-13 (CANH) - A35-26 (CANL) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (ECM - NO. 3 CAN JUNCTION CONNECTOR)

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


    1. Reconnect all wire harness connectors.

    2. Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

      Click here

    3. B002KA7C15
      *a

      Component with harness connected

      (Central Gateway ECU [Network Gateway ECU])

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I164-18 (CA4H) - I164-17 (CA4L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω

      Tech Tips

      If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECU OR SENSOR

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR