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Inspection Procedure

NOTE: When replacing the master cylinder solenoid, perform zero point calibration (See CALIBRATION  ).
  1. INSPECT DOWNHILL ASSIST CONTROL INDICATOR LIGHT 
    1. Disconnect the skid control ECU (S28) connector.
    2. Ground terminal HDCW of the skid control ECU connector.
    3. Turn the ignition switch to ON.
    4. Check that the downhill assist control indicator light comes on.

      OK: 

      Downhill assist control indicator light comes on. 

      OK: REPLACE MASTER CYLINDER SOLENOID 

      NG: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - COMBINATION METER) 
    1. Disconnect the combination meter connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION CONDITION CHART

      Tester Connection Condition Specified Condition
      S28-33 (HDCW) - C8-12 Always Below 1 Ω
      S28-33 (HDCW) - Body ground Always 10 kΩ or higher

      NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

      Fig 1: Identifying Skid Control ECU Connector Terminal And Combination Meter Connector Terminal
      G06129564Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      OK: Go to next step 

  3. INSPECT COMBINATION METER ASSEMBLY 
    1. Check the combination meter system (See HOW TO PROCEED WITH TROUBLESHOOTING ).

      NG: REPLACE COMBINATION METER ASSEMBLY 

      OK: Go to next step 

  4. INSPECT SKID CONTROL ECU (HDCS TERMINAL) 
    1. Disconnect the skid control ECU connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION CONDITION CHART

      Tester Connection Condition Specified Condition
      S28-44 (HDCS) - Body ground Downhill assist control switch Is pushed in Below 1 Ω

      OK: REPLACE MASTER CYLINDER SOLENOID 

      Fig 2: Inspecting Skid Control ECU (HDCS Terminal)
      G05556596Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      NG: Go to next step 

  5. INSPECT DOWNHILL ASSIST CONTROL SWITCH  (See INSPECTION PROCEDURE  )

    NG: REPLACE DOWNHILL ASSIST CONTROL SWITCH 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU AND BODY GROUND - DOWNHILL ASSIST CONTROL SWITCH) 
    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION CONDITION CHART

      Tester Connection Condition Specified Condition
      S28-44 (HDCS) - D5-3 Always Below 1 Ω
      S28-44 (HDCS) - Body ground Always 10 kΩ or higher
      D5-4 - Body ground Always Below 1 Ω

      NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

      Fig 3: Identifying Skid Control ECU Connector Terminal And Downhill Assist Control Switch Connector Terminal
      G05556598Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      OK: CHECK FOR INTERMITTENT PROBLEMS  (See CHECK FOR INTERMITTENT PROBLEMS  )

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