CAN COMMUNICATION SYSTEM(w/ Central Gateway ECU) Check Bus 1 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the bus 1 main lines and/or bus 1 branch lines when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the central gateway ECU is below 54 Ω.

Symptom Trouble Area
Resistance between terminals 15 (CA5H) and 16 (CA5L) of central gateway ECU is below 54 Ω.

  • Short in bus 1 main lines

  • Short in bus 1 branch lines

  • Central gateway ECU

  • Forward recognition camera*1

  • Driving support ECU assembly*1

  • Millimeter wave radar sensor assembly*1

  • Hybrid vehicle control ECU assembly

  • Blind spot monitor sensor LH*2

  • No. 4 CAN junction connector

  • No. 5 CAN junction connector

WIRING DIAGRAM

A0005G3E04

CAUTION / NOTICE / HINT

Note


  • 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.

  • 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.

  • 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), turn the LDA main switch on, turn the blind spot monitor main switch on, wait at least 52 seconds and then drive the vehicle at a speed of 36 km/h (22 mph) or more for 7 seconds 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 Click here.

Tech Tips


  • 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.

  • 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.

  • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines. When the connectors have been disconnected from the CAN junction connector, reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

PROCEDURE


  1. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU)


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

    2. Disconnect the H201 No. 4 CAN junction connector.

      Tech Tips


      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      A0005HBE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to Central Gateway ECU
    3. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

    CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU - NO. 4 CAN J/C) Click here

    OK

  2. CHECK FOR SHORT IN CAN BUS LINES (BRANCH LINE)


    1. Reconnect the H201 No. 4 CAN junction connector.

    2. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

      Connect the probes of an electrical tester to terminals 15 (CA5H) and 16 (CA5L) of the central gateway ECU connector.

    3. While observing the resistance value shown on the tester, disconnect connectors (H203, H204, H205 and U26) from the No. 4 CAN junction connector or No. 5 CAN junction connector one by one until the resistance becomes normal (between 54 and 69 Ω).

      Tech Tips


      • Disconnect the branch line connectors other than CAN main bus line connector.

      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      A0005CPE03
      Text in Illustration
      *A w/ Lexus Safety System + *B w/ Blind Spot Monitor System
      *1 Forward Recognition Camera *2 Driving Support ECU Assembly
      *3 Millimeter Wave Radar Sensor Assembly *4 Central Gateway ECU
      *5 No. 4 CAN Junction Connector *6 Hybrid vehicle control ECU assembly
      *7 Blind Spot Monitor Sensor LH *8 No. 5 CAN Junction Connector
      A00068ZE08
      Text in Illustration
      *a

      Component without harness connected

      (No. 4 CAN Junction Connector)

      		 - -
      Wiring Color
      No. 4 CAN Junction Connector Code Color (CANH Side) Color (CANL Side)
      Millimeter wave radar sensor assembly* H204 Y LG
      Central gateway ECU H201 L LG
      No. 5 CAN junction connector H202 G LG
      Forward recognition camera* H203 R LG
      Driving support ECU assembly* H205 B LG

      • *: w/ Lexus Safety System +

      A0008A4E05
      Text in Illustration
      *a

      Component without harness connected

      (No. 5 CAN Junction Connector)

      		 - -
      Wiring Color
      CAN Junction Connector RH1 Side Code Color (CANH Side) Color (CANL Side)
      Blind spot monitor sensor LH* U26 V LG
      Hybrid vehicle control ECU assembly U28 Y LG
      No. 4 CAN junction connector U25 G LG

      • *: w/ Blind Spot Monitor System

      Note

      Do not reconnect the disconnected connectors until this inspection is complete because there may be a short in 2 or more branch lines.

      Result
      Symptom Proceed to
      The resistance is still below 54 Ω when all the specified connectors are disconnected. (There are no shorts between a pair of branch lines.) A
      The resistance becomes normal (between 54 and 69 Ω) when a connector is disconnected. (There is a short between one or more pairs of branch lines.) B

    4. When there is a short in one or more of the branch lines:


      1. Reconnect all of the connectors to the CAN junction connector, except for the one that was disconnected last (the short-circuited bus line). Check that the resistance shown on the tester is normal (between 54 and 69 Ω) to confirm that there is a short in the one branch line only.


    B

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

    A

  3. CHECK FOR SHORT IN CAN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY)


    1. Reconnect all of the connectors to the No. 4 CAN junction connector and No. 5 CAN junction connector.

    2. Disconnect the U28 No. 5 CAN junction connector.

      Tech Tips


      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      A0008U0E01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 5 CAN Junction Connector)

      		 *b to Hybrid Vehicle Control ECU Assembly
    3. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω
      Result
      Symptom Proceed to
      The resistance is still below 54 Ω when the combination meter assembly connector is disconnected. (There are no shorts in the combination meter assembly or between its main bus lines.) A
      The resistance falls within the specified range (between 108 and 132 Ω) (the other terminating resistor is normal) when the combination meter assembly connector is disconnected. (There is a short in the combination meter assembly or between its main bus lines.) B

    B

    CHECK FOR SHORT IN CAN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 5 CAN J/C) Click here

    A

  4. CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN J/C)


    1. Reconnect the U28 No. 5 CAN junction connector.

    2. Disconnect the H202 No. 4 CAN junction connector.

      Tech Tips


      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      A0007GFE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 4 CAN Junction Connector)

      		 *b to No. 5 CAN Junction Connector
    3. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    NG

    REPLACE NO. 4 CAN JUNCTION CONNECTOR

    OK

  5. CHECK FOR SHORT IN CAN BUS LINES (NO. 4 CAN J/C - NO. 5 CAN J/C)


    1. Reconnect the H202 No. 4 CAN junction connector.

    2. Disconnect the U25 No. 5 CAN junction connector.

      Tech Tips


      • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.

      • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

      A0007PKE01
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to No. 5 CAN Junction Connector)

      		 *b to No. 4 CAN Junction Connector
    3. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE NO. 5 CAN JUNCTION CONNECTOR

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (NO. 4 CAN J/C - NO. 5 CAN J/C)

  6. CHECK FOR SHORT IN CAN BUS LINES (ECU, SENSOR)


    1. Reconnect the connector for the short-circuited branch line to the CAN junction connector (the connector that caused the bus line resistance to become normal (between 54 and 69 Ω) when it was disconnected).

    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. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) 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.


    OK

    REPLACE CORRESPONDING ECU OR SENSOR

    NG

    REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH LINES OR CONNECTOR

  7. CHECK FOR SHORT IN CAN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY - NO. 5 CAN J/C)


    1. Reconnect the U28 No. 5 CAN junction connector.

    2. Disconnect the H211 hybrid vehicle control ECU assembly connector.

    3. A0009HNE02
      Text in Illustration
      *a

      Component with harness connected

      (Central Gateway ECU)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (HYBRID VEHICLE CONTROL ECU ASSEMBLY)

  8. CHECK FOR SHORT IN CAN BUS LINES (CENTRAL GATEWAY ECU - NO. 4 CAN J/C)


    1. Reconnect the H201 No. 4 CAN junction connector.

    2. A00095IE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Central Gateway ECU)

      Disconnect the H195 central gateway ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H195-15 (CA5H) - H195-16 (CA5L) Cable disconnected from negative (-) auxiliary battery terminal 108 to 132 Ω

    OK

    REPLACE CENTRAL GATEWAY ECU Click here

    NG

    REPAIR OR REPLACE CAN MAIN BUS LINES (CENTRAL GATEWAY ECU)