LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Toyota >> 2018 >> 4Runner TRD Pro >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Communication Devices >> Can Communication System - Circuit Tests (1 Of 3) & Diagnostic Codes >> Can Communication System >> DTC U1002: Lost Communication with Gateway Module (MS Bus); DTC U1114: Lost Communication with Main Switch Module [08/2015 - 08/2019] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC U1002: Lost Communication with Gateway Module (MS Bus); DTC U1114: Lost Communication with Main Switch Module [08/2015 - 08/2019]: Procedure

  1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL 
    1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and branch wire.
      WARNING:

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

      NOTE:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Refer to INITIALIZATION [08/2015 - 08/2019] ).

    Result: 

    NEXT 

    See step  2

  2. CHECK FOR OPEN IN CAN BUS MAIN WIRE (MAIN BODY ECU - DRIVE MONITOR SWITCH) 
    1. Disconnect the F10 main body ECU (multiplex network body ECU) connector.
      GTY728689Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      F10-9 (CANP) - F10-10 (CANN) Ignition switch off 108 to 132 Ω
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Main Body ECU [Multiplex Network Body ECU])

    Result: 

    NG 

    See step  4

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) battery terminal.
      GTY731412Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Main Body ECU [Multiplex Network Body ECU])      		 *b Front view of wire harness connector
      (to Main Body ECU [Multiplex Network Body ECU])
      NOTE:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Refer to INITIALIZATION [08/2015 - 08/2019] ).

    2. Remove the main body ECU (multiplex network body ECU) (Refer to REMOVAL [08/2015 - 08/2019] ).
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F10-3 (GND2) - Body ground Always Below 1 Ω
      A-11 (GND1) - Body ground Always Below 1 Ω
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A-31 (ALTB) - Body ground Always 11 to 14 V
      A-30 (BECU) - Body ground Always 11 to 14 V
      A-29 (ACC) - Body ground Ignition switch ACC 11 to 14 V
      A-32 (IG) - Body ground Ignition switch ON 11 to 14 V

    Result: 

    OK 

    REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 

    (Refer to REMOVAL [08/2015 - 08/2019] )

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. CONNECT CONNECTOR 
    1. Reconnect the F10 main body ECU (multiplex network body ECU) connector.

    Result: 

    NEXT 

    See step  5

  5. CHECK FOR OPEN IN CAN BUS MAIN WIRE (DRIVE MONITOR SWITCH - MAIN BODY ECU) 
    1. Disconnect the U1 drive monitor switch connector.
      GTY731977Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Switch Condition Specified Condition
      U1-1 (CANP) - U1-2 (CANN) Ignition switch off 108 to 132 Ω
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Drive Monitor Switch)

    Result: 

    NG 

    REPAIR OR REPLACE CAN MAIN WIRE OR CONNECTOR (MAIN BODY ECU - DRIVE MONITOR SWITCH) 

    Result: 

    OK 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (DRIVE MONITOR SWITCH - BATTERY AND BODY GROUND) 
    1. Connect the cable to the negative (-) battery terminal.
      GTY696711Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE:

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Refer to INITIALIZATION [08/2015 - 08/2019] ).

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      U1-7 (GND) - Body ground Always Below 1 Ω
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      U1-6 (+B) - Body ground Always 11 to 14 V
      U1-12 (IG) - Body ground Ignition switch ON 11 to 14 V
      TEXT IN ILLUSTRATION

      *a Rear view of wire harness connector
      (to Drive Monitor Switch)

    Result: 

    OK 

    REPLACE DRIVE MONITOR SWITCH 

    (Refer to REMOVAL [08/2015 - ] )

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

scientia non olet · About LEMON Manuals