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Check CAN Bus Line for Short to GND [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR SHORT TO GND IN CAN BUS LINE (DLC3 BRANCH LINE) 
    1. Disconnect the cable from the negative (-) auxiliary battery terminal.
    2. Disconnect the H119 DLC3 branch line connector.
      GTY415855Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to CAN Junction Connector LH1)
      *b to DLC3
      NOTE:
      • Before disconnecting the connector, make a note of where it is connected.
      • Reconnect the connector to its original position.
    3. Measure the resistance according to the value(s) in the table below.
      GTY398705Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      TEXT IN ILLUSTRATION

      *1 DLC3

    NG → REPAIR OR REPLACE CAN BRANCH LINE CONNECTED TO DLC3 

    OK: Go to next step 

  2. CHECK FOR SHORT TO GND IN CAN BUS LINE 
    1. Reconnect the H119 DLC3 branch line connector.
    2. Disconnect the connectors from the CAN junction connector LH1 and CAN junction connector RH1 one at a time.

      HINT: 

      Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the CAN junction connector LH1 and CAN junction connector RH1.

      GTY398705Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *1 DLC3
    3. Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 4 (CG), and between terminals 14 (CANL) and 4 (CG) of the DLC3 each time a connector is disconnected.
      GTY407368Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *A w/ Intuitive Parking Assist System *B w/ Navigation System
      *C w/ Audio and Visual System (w/ Multi-display with Parking Assist Monitor System) *D w/ Audio and Visual System (w/ Multi-display without Parking Assist Monitor System)
      *1 Clearance Warning ECU Assembly *2 ECM
      *3 Air Conditioning Amplifier Assembly *4 Airbag Sensor Assembly
      *5 Certification ECU (Smart Key ECU assembly) *6 Power Steering ECU with Motor Assembly
      *7 Multi-media Module Receiver Assembly *8 Radio Receiver Assembly
      *9 Combination Meter Assembly *10 Power Management Control ECU
      *11 DLC3 *12 Brake Booster with Master Cylinder Assembly (Skid Control ECU)
      *13 Steering Sensor *14 Main Body ECU (Multiplex Network Body ECU)
      *15 CAN Junction Connector RH1 *16 CAN Junction Connector LH1
      GTY414807Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Component without harness connected
      (CAN Junction Connector LH1)      		 - -
      WIRING COLOR

      CAN Junction Connector LH1 Side Code Color (CANH Side) Color (CANL Side)
      CAN main bus line (bus line connecting CAN junction connector LH1 and CAN junction connector RH1) H116 R W
      Combination meter assembly H117 G W
      Main body ECU (Multiplex network body ECU) H118 V W
      DLC3 H119 L W
      Steering sensor H120 P W
      Power management control ECU H130 B W
      Brake booster with master cylinder assembly (Skid control ECU) H131 BE W
      GTY398971Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Component without harness connected
      (CAN Junction Connector RH1)      		 - -
      WIRING COLOR

      CAN Junction Connector RH1 Side Code Color (CANH Side) Color (CANL Side)
      Power steering ECU with motor assembly H121 B W
      CAN main bus line (bus line connecting CAN junction connector LH1 and CAN junction connector RH1) H122 R W
      Air conditioning amplifier assembly H123 G W
      Airbag sensor assembly H124 Y W
      ECM H125 L W
      Certification ECU (Smart key ECU assembly) H127 V W
      • Multi-media module receiver assembly*1*2
      • Radio receiver assembly*3
      		 H128 BE W
      Clearance warning ECU assembly*4 H132 P W
      • *1: w/ Navigation system
      • *2: w/ Audio and visual system (w/ Multi-display with parking assist monitor system)
      • *3: w/ Audio and visual system (w/ Multi-display without parking assist monitor system)
      • *4: w/ Intuitive parking assist system
      NOTE:

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

      Result

      Symptom Proceed to
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) is still below 200 Ω when all the specified connectors are disconnected from the CAN junction connector. (There is a short to GND in the CAN main bus lines between the CAN junction connector LH1 and CAN junction connector RH1.) A
      The resistance between terminals 6 (CANH) and 4 (CG), or the resistance between 14 (CANL) and 4 (CG) becomes normal (200 Ω or more) when a connector is disconnected from the CAN junction connector. (There is a short to GND in one of the areas that relate to the disconnected bus lines.) B
    4. When there is a short to GND in one or more of the bus lines that connect to an ECU (or sensor):
      1. Reconnect all of the connectors to the CAN junction connectors, except for the one that was disconnected last (the bus line that is shorted to GND). Check that the resistance shown on the tester is normal (200 Ω or more) to confirm that there is a short to GND in the one branch line only.

        HINT: 

        • 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.
    5. When there is no short to GND in any of the bus lines that connect to the ECUs and sensors:
      1. With all the specified connectors for ECUs and sensors disconnected, proceed with the inspection of the CAN bus main lines between the CAN junction connector LH1 and CAN junction connector RH1.

    B → See step   5 

    A: Go to next step 

  3. CHECK FOR SHORT TO GND IN CAN BUS LINE (CAN J/C LH1) 
    1. Disconnect the H116 CAN main bus line connector.
      GTY408031Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to CAN Junction Connector LH1)
      *b to CAN Junction Connector RH1
      NOTE:
      • Before disconnecting the connector, make a note of where it is connected.
      • Reconnect the connector to its original position.
    2. Measure the resistance according to the value(s) in the table below.
      GTY398705Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      TEXT IN ILLUSTRATION

      *1 DLC3

    NG → REPLACE CAN JUNCTION CONNECTOR LH1 

    OK: Go to next step 

  4. CHECK FOR SHORT TO GND IN CAN BUS LINE (CAN J/C LH1 - CAN J/C RH1) 
    1. Reconnect the H116 CAN main bus line connector.
    2. Disconnect the H122 CAN main bus line connector.
      GTY398263Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to CAN Junction Connector RH1)
      *b to CAN Junction Connector LH1
      NOTE:
      • Before disconnecting the connector, make a note of where it is connected.
      • Reconnect the connector to its original position.
    3. Measure the resistance according to the value(s) in the table below.
      GTY398705Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Resistance

      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      TEXT IN ILLUSTRATION

      *1 DLC3

    NG → REPAIR OR REPLACE CAN MAIN BUS LINE (CAN J/C LH1 - CAN J/C RH1) 

    OK → REPLACE CAN JUNCTION CONNECTOR RH1 

  5. CHECK FOR SHORT TO GND IN CAN BUS LINE (ECU, SENSOR) 
    1. Reconnect the connector of the bus line that is shorted to GND to the CAN junction connector (the connector that caused the bus line resistance to change to 200 Ω or more when it was disconnected).
    2. Disconnect the connector that includes the DLC3 connected CAN lines (such as CANH and CANL) from the ECU (or sensor) to which the bus line shorted to GND is connected. Refer to TERMINALS OF ECU [08/2013 - ] .
      GTY398705Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H29-6 (CANH) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      H29-14 (CANL) - H29-4 (CG) Cable disconnected from negative (-) auxiliary battery terminal 200 Ω or higher
      TEXT IN ILLUSTRATION

      *1 DLC3

      HINT: 

      If the resistance changes to 200 Ω 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 BUS LINE OR CONNECTOR 

    OK → REPLACE CORRESPONDING ECU OR SENSOR 

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