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CAN COMMUNICATION SYSTEM (for LHD), Diagnostic DTC:U0122, U0129

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DTC Code DTC Name
U0122 Lost Communication with Vehicle Dynamics Control Module
U0129 Lost Communication with Brake System Control Module
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DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U0122 There is no communication from the skid control ECU assembly.

  • Power source or inside of skid control ECU assembly

  • Skid control ECU assembly CAN branch wire or connector

  • Skid control ECU assembly
U0129 There is no communication from the skid control ECU assembly.

  • Power source or inside of skid control ECU assembly

  • Skid control ECU assembly CAN branch wire or connector

  • Skid control ECU assembly
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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tip:

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

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PROCEDURE


  1. Click here

    PRECAUTION

    Note:

    After turning the power switch off, waiting time may be required before disconnecting the cable from the auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the auxiliary battery terminal notice before proceeding with work (Click here).


  2. Click here

    DISCONNECT CABLE FROM NEGATIVE AUXILIARY BATTERY TERMINAL


    1. Disconnect the cable from the negative (-) auxiliary battery terminal before measuring the resistances of the CAN main wire and the CAN branch wire.

      CAUTION:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

      Note:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Click here).


  3. Click here

    CHECK FOR OPEN IN CAN BUS WIRE (SKID CONTROL ECU ASSEMBLY CAN BRANCH WIRE)


    1. A01H05IE02

      Disconnect the skid control ECU assembly connectors.

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

      Standard Resistance
      Table 1. Steering Bus
      Tester Connection Switch Condition Specified Condition
      A21-30 (CA1H) - A21-29 (CA1L) Power switch off 54 to 69 Ω
      Table 2. Braking and Driving Bus
      Tester Connection Switch Condition Specified Condition
      A19-7 (CA2H) - A19-6 (CA2L) Power switch off 54 to 69 Ω
      Table 3. Text in Illustration
      *A Steering Bus
      *B Braking and Driving Bus
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

  4. Click here

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU ASSEMBLY - BATTERY AND BODY GROUND)


    1. A01H05IE01

      Connect the cable to the negative (-) auxiliary battery terminal.

      Note:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Click here).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A19-43 (+BI1) - Body ground Always 11 to 14 V
      A21-38 (+BI2) - Body ground Always 11 to 14 V
      A19-29 (+BI3) - Body ground Always 11 to 14 V
      A21-22 (+BI4) - Body ground Always 11 to 14 V
      A19-46 (IG1) - Body ground Power switch on (IG) 11 to 14 V
      A21-46 (IG2) - Body ground Power switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A19-1 (GND) - Body ground Always Below 1 Ω
      A21-1 (GND4) - Body ground Always Below 1 Ω
      Table 4. Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

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    REPAIR OR REPLACE SKID CONTROL ECU ASSEMBLY CAN BRANCH WIRE OR CONNECTOR (CA1H, CA1L, CA2H, CA2L)

  6. Click here

    REPLACE SKID CONTROL ECU ASSEMBLYClick here

  7. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR