CAN COMMUNICATION SYSTEM(for LHD), Diagnostic DTC:U1121

DTC Code DTC Name
U1121 Lost Communication with Driver Monitor ECU

DESCRIPTION

DTC Code DTC Detection Condition Trouble Area
U1121 There is no communication from the driver monitor ECU assembly.

  • Power source or inside of driver monitor ECU assembly

  • Driver monitor ECU assembly CAN branch wire or connector

  • Driver monitor ECU assembly

WIRING DIAGRAM

A000XLPE19
*a No. 13 Junction Connector
*b from D-IG1-1 Relay
*c Driver Monitor ECU Assembly

CAUTION / NOTICE / HINT

Note

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

Tech Tips

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

PROCEDURE


  1. 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.


    NEXT

  2. 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.


    NEXT

  3. CHECK FOR OPEN IN CAN BUS WIRE (DRIVER MONITOR ECU ASSEMBLY CAN BRANCH WIRE)


    1. A000ZB8E02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Driver Monitor ECU Assembly)

      Disconnect the driver monitor ECU assembly connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      L158-12 (CANH) - L158-11 (CANL) Power switch off 54 to 69 Ω

    NG

    REPAIR OR REPLACE DRIVER MONITOR ECU ASSEMBLY CAN BRANCH WIRE OR CONNECTOR (CANH, CANL)

    OK

  4. CHECK HARNESS AND CONNECTOR (DRIVER MONITOR ECU ASSEMBLY - BATTERY AND BODY GROUND)


    1. A000U32E02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to Driver Monitor ECU Assembly)

      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 Switch Condition Specified Condition
      L158-1 (IG) - 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
      L158-2 (GND) - Body ground Always Below 1 Ω

    OK

    REPLACE DRIVER MONITOR ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR