VEHICLE STABILITY CONTROL SYSTEM (for Hydraulic Brake Booster), Diagnostic DTC:C1379

DTC Code DTC Name
C1379 Downhill Assist Control Switch Malfunction (Test Mode DTC)

DESCRIPTION

w/ Downhill Assist Control:

DTC C1379 is cleared when the downhill assist control switch sends a downhill assist control operation signal or when test mode ends.

w/ Crawl Control:

DTC C1379 is cleared when the crawl control switch sends a crawl control operation signal or when test mode ends.

DTC Code DTC Detection Condition Trouble Area
C1379 Stored only during test mode.

  • Downhill assist control switch (w/ Downhill Assist Control)

  • Crawl control switch (w/ Crawl Control)

  • Harness or connector

  • Master cylinder solenoid (Skid control ECU)

WIRING DIAGRAM

A00OASAE02
A00O61OE06

INSPECTION PROCEDURE

Note

When replacing the master cylinder solenoid, perform calibration Click here.

PROCEDURE


  1. CONFIRM VEHICLE SPECIFICATIONS


    1. Confirm the vehicle specifications.

      Result
      Result Proceed to
      w/ Downhill Assist Control A
      w/ Crawl Control B

    B

    CHECK CAN BUS Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (DOWNHILL ASSIST CONTROL SW)


    1. Turn the ignition switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the intelligent tester on.

    5. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    6. Check the Data List for proper functioning of the downhill assist control switch.

      ABS/VSC/TRC
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Downhill Assist Control SW Downhill assist control switch / ON or OFF

      ON: Downhill assist control on

      OFF: Downhill assist control off

      		 -
      OK
      The intelligent tester displays ON or OFF according to downhill assist control switch operation.

    NG

    Click here

    OK

  3. CHECK TEST MODE DTC


    1. Perform the downhill assist control switch check in the Test Mode Procedure Click here.

      OK
      Test mode DTC C1379 is cleared.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here

    A

    USE SIMULATION METHOD TO CHECK Click here

  4. INSPECT DOWNHILL ASSIST CONTROL SWITCH


    1. Remove the downhill assist control switch Click here.

    2. A00O68OE02
      Text in Illustration
      *a

      Component without harness connected

      (Downhill Assist Control Switch)

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      1 - 4 Not pushed in 10 kΩ or higher
      Pushed in Below 1 Ω

    NG

    REPLACE DOWNHILL ASSIST CONTROL SWITCH Click here

    OK

  5. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - DOWNHILL ASSIST CONTROL SWITCH)


    1. Disconnect the A7 skid control ECU connector.

    2. Disconnect the G10 downhill assist control switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A7-44 (HDCS) - G10-4 Always Below 1 Ω
      A7-44 (HDCS) - Body ground Always 10 kΩ or higher
      G10-1 - Body ground Always Below 1 Ω
      Result
      Result Proceed to
      NG A
      OK (for LHD) B
      OK (for RHD) C

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here

    A

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK CAN BUS


    1. Check that there are no problems with the CAN communication system (for LHD: Click here, for RHD: Click here.

      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) Click here

    C

    GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) Click here

    A

  7. READ VALUE USING INTELLIGENT TESTER (CRAWL CONTROL SWITCH)


    1. Turn the ignition switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the intelligent tester on.

    5. Enter the following menus: Body Electrical / D-SEAT SW / Data List.

    6. Check the Data List for proper functioning of the crawl control switch.

      D-SEAT SW
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Crawl Control Main Switch Crawl control switch (ON/OFF switch)/ ON or OFF

      ON: Crawl control on

      OFF: Crawl control off

      		 -
      Crawl Control Up Switch Crawl Control Switch (Speed selector switch up side)/ ON or OFF

      ON: Speed selector switch up side pushed and held

      OFF: Speed selector switch up side not pushed

      		 -
      Crawl Control Down Switch Crawl Control Switch (Speed selector switch down side)/ ON or OFF

      ON: Speed selector switch down side pushed and held

      OFF: Speed selector switch down side not pushed

      		 -
      OK
      The intelligent tester displays according to crawl control switch operation.

    NG

    CHECK HARNESS AND CONNECTOR (CRAWL CONTROL SWITCH - DRIVING SUPPORT SWITCH CONTROL ECU) Click here

    OK

  8. CHECK TEST MODE DTC


    1. Perform the crawl control switch check in the Test Mode Procedure Click here.

      OK
      Test mode DTC C1379 is cleared.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    REPLACE MASTER CYLINDER SOLENOID Click here

    C

    REPLACE MASTER CYLINDER SOLENOID Click here

    A

    USE SIMULATION METHOD TO CHECK Click here

  9. CHECK HARNESS AND CONNECTOR (CRAWL CONTROL SWITCH - DRIVING SUPPORT SWITCH CONTROL ECU)


    1. Disconnect the G125 crawl control switch connector.

    2. Disconnect the G76 driving support switch control ECU connector.

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

      Standard Resistance
      for LHD
      Tester Connection Condition Specified Condition
      G125-4 (ECU) - G76-15 (SWI3) Always Below 1 Ω
      G125-4 (ECU) - Body ground Always 10 kΩ or higher
      G125-6 (UP) - G76-13 (SWI4) Always Below 1 Ω
      G125-6 (UP) - Body ground Always 10 kΩ or higher
      G125-5 (DN) - G76-14 (SWI5) Always Below 1 Ω
      G125-5 (DN) - Body ground Always 10 kΩ or higher
      G125-1 (E) - Body ground Always Below 1 Ω
      for RHD
      Tester Connection Condition Specified Condition
      G125-4 (ECU) - G76-15 (SWI3) Always Below 1 Ω
      G125-4 (ECU) - Body ground Always 10 kΩ or higher
      G125-5 (UP) - G76-13 (SWI4) Always Below 1 Ω
      G125-5 (UP) - Body ground Always 10 kΩ or higher
      G125-6 (DN) - G76-14 (SWI5) Always Below 1 Ω
      G125-6 (DN) - Body ground Always 10 kΩ or higher
      G125-1 (E) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. INSPECT CRAWL CONTROL SWITCH


    1. Remove the crawl control switch Click here.

    2. A00O508E02
      Text in Illustration
      *A for LHD
      *B for RHD
      *1 Speed Selector Switch
      *2 ON/OFF Switch
      *a

      Component without harness connected

      (Crawl Control Switch)
      *b Illustration shows switch from LHD vehicles

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

      Standard Resistance
      for LHD
      Tester Connection Switch Condition Specified Condition
      6 (UP) - 1 (E) + Below 1 Ω
      FREE 10 kΩ or higher
      5 (DN) - 1 (E) - Below 1 Ω
      FREE 10 kΩ or higher
      4 (ECU) - 1 (E) ON/OFF: Pressed Below 1 Ω
      ON/OFF: Not pressed 10 kΩ or higher
      for RHD
      Tester Connection Switch Condition Specified Condition
      5 (UP) - 1 (E) + Below 1 Ω
      FREE 10 kΩ or higher
      6 (DN) - 1 (E) - Below 1 Ω
      FREE 10 kΩ or higher
      4 (ECU) - 1 (E) ON/OFF: Pressed Below 1 Ω
      ON/OFF: Not pressed 10 kΩ or higher

    NG

    REPLACE CRAWL CONTROL SWITCH Click here

    OK

    REPLACE DRIVING SUPPORT SWITCH CONTROL ECU Click here