VEHICLE STABILITY CONTROL SYSTEM Downhill Assist Control Indicator Light does not Come ON

DESCRIPTION

Even if the downhill assist control switch is pressed, the downhill assist control indicator light blinks and downhill assist control does not activate under the following conditions:


WIRING DIAGRAM

A01QSNOE01
*a Downhill Assist Control Switch
*b Combination Meter Assembly
*c Skid Control ECU (Brake Actuator Assembly)
*d CAN Communication Line

CAUTION / NOTICE / HINT

Note

When replacing the skid control ECU (brake actuator assembly), perform zero point calibration.

Click here

PROCEDURE


  1. CHECK CAN COMMUNICATION SYSTEM


    1. Check if CAN communication system DTCs are output.

      for LHD with Central Gateway ECU: Click here

      for RHD with Central Gateway ECU: Click here

      for LHD without Central Gateway ECU: Click here

      for RHD without Central Gateway ECU: Click here

      Result
      Proceed to
      DTC is not output
      DTC is output (for LHD with Central Gateway ECU)
      DTC is output (for RHD with Central Gateway ECU)
      DTC is output (for LHD without Central Gateway ECU)
      DTC is output (for RHD without Central Gateway ECU)

    DTC is output (for LHD with Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for RHD with Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for LHD without Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is output (for RHD without Central Gateway ECU)

    CHECK CAN COMMUNICATION SYSTEM Click here

    DTC is not output

  2. CHECK HARNESS AND CONNECTOR (HDCS TERMINAL)


    1. Turn the ignition switch off.

    2. Disconnect the A80 skid control ECU (brake actuator assembly) connector.

    3. A01QPOVC32
      *a

      Front view of wire harness connector

      (to Skid Control ECU [Brake Actuator Assembly])

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A80-27 (HDCS) - Body ground Downhill assist control switch is pushed Below 1 Ω
      A80-27 (HDCS) - Body ground Downhill assist control switch is not pushed 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    INSPECT DOWNHILL ASSIST CONTROL SWITCH Click here

    OK

  3. PERFORM ACTIVE TEST USING GTS (DOWNHILL ASSIST CONTROL LIGHT)


    1. Reconnect the A80 skid control ECU (brake actuator assembly) connector.

    2. Connect the GTS to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the GTS on.

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

    6. According to the display on the GTS, perform the Active Test.


      Chassis > ABS/VSC/TRC > Active Test
      Tester Display Measurement Item Control Range Diagnostic Note
      Downhill Assist Control Light Downhill assist control indicator light Indicator light OFF/ON

      Observe combination meter

      Vehicle condition: Vehicle stopped

    7. When performing the ABS Warning Light Active Test, check Downhill assist control indicator light in the Data List.


      Chassis > ABS/VSC/TRC > Data List
      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Downhill Assist Control Light Downhill assist control indicator light ON or OFF

      OFF: Downhill assist control indicator light off

      ON: Downhill assist control indicator light on

      w/ Downhill Assist Control:

      The item is displayed on the GTS but not used.

      OFF: Always

      Chassis > ABS/VSC/TRC > Active Test
      Active Test Display
      Downhill Assist Control Light
      Data List Display
      Downhill Assist Control Light
      Result
      Result Proceed to
      Downhill assist control indicator light in the Data List does not change using the Active Test A
      Downhill assist control indicator light in the Data List turns ON/OFF using the Active Test B

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    B

  4. INSPECT COMBINATION METER ASSEMBLY


    1. Turn the ignition switch off.

    2. Perform Active Test of the combination meter assembly using the GTS.


      Body Electrical > Combination Meter > Active Test
      Tester Display
      Indicat. Downhill Assist Control

    3. Check the combination meter assembly.

      OK
      The Downhill assist control indicator light turns on or off in accordance with the GTS.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    NG

    INSPECT METER / GAUGE SYSTEM Click here

  5. INSPECT DOWNHILL ASSIST CONTROL SWITCH


    1. Turn the ignition switch off.

    2. Remove the downhill assist control switch.

      Click here

    3. Inspect the downhill assist control switch.

      Click here

      Result
      Result
      OK
      NG

    NG

    REPLACE DOWNHILL ASSIST CONTROL SWITCH Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - DOWNHILL ASSIST CONTROL SWITCH)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A80-27 (HDCS) - G29-4 Always Below 1 Ω
      A80-27 (HDCS) or G29-4 - Body ground Always 10 kΩ or higher
      G29-1 - Body ground Always Below 1 Ω
      Result
      Result
      OK
      NG

    OK

    USE SIMULATION METHOD TO CHECK Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR