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Home >> Lexus >> 2009 >> RX 350 FWD >> Repair and Diagnosis >> Suspension >> Rear Suspension >> Air Suspension System (Diagnostic Codes & Circuit Tests) >> Air Suspension System >> DTC C1737/31: Right Front Height Control Solenoid Valve Circuit; DTC C1738/32: Left Front Height Control Solenoid Valve Circuit; DTC C1739/33: Right Rear Height Control Solenoid Valve Circuit; DTC C1740/34: Left Rear Height Control Solenoid Valve Circuit >> Procedure

DTC C1737/31: Right Front Height Control Solenoid Valve Circuit; DTC C1738/32: Left Front Height Control Solenoid Valve Circuit; DTC C1739/33: Right Rear Height Control Solenoid Valve Circuit; DTC C1740/34: Left Rear Height Control Solenoid Valve Circuit: Procedure

  1. RECONFIRM DTC 
    1. Check DTCs. Refer to DTC CHECK / CLEAR .
      1. Confirm if the DTC C1761/61 and/or C1774/74 is recorded.

        OK

        DTC C1761/61 and/or C1774/74 is output.

        HINT: 

        If either DTCC1761/61 (ECU malfunction). Refer to DTC C1761/61: ECU Malfunction  or C1774/74 (power source circuit). Refer to DTC C1774/74: Power Source Circuit  is displayed, carry out the necessary inspection. If they are output at the same time, carry out the necessary inspection for DTC C1774/74 first.

    NG → REPAIR CIRCUIT INDICATED BY OUTPUT CODE 

    OK: Go to next step 

  2. PERFORM ACTIVE TEST USING TECHSTREAM 

    HINT: 

    When not using Techstream, go to step  3.

    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON position, and push the Techstream main switch on.
    3. Select the item below in the ACTIVE TEST, and operate it with the Techstream.

      Air suspension

      Item Vehicle Condition / Test Details Diagnostic Note
      FR Solenoid Turn OFF right front solenoid valve one second after turning it ON Operation of solenoid (clicking sound) can be heard
      FL Solenoid Turn OFF left front solenoid valve one second after turning it ON Operation of solenoid (clicking sound) can be heard
      RR Solenoid Turn OFF right rear solenoid valve one second after turning it ON Operation of solenoid (clicking sound) can be heard
      RL Solenoid Turn OFF left rear solenoid valve one second after turning it ON Operation of solenoid (clicking sound) can be heard
    4. Check whether the height control solenoid valve has continuity (will vibrate).

      OK

      The solenoid makes sound, and the height control solenoid valve has continuity (will vibrate).

    NG → Go to next step 

    OK → REPLACE SUSPENSION CONTROL ECU 

  3. INSPECT HEIGHT CONTROL SOLENOID VALVE 
    1. HEIGHT CONTROL SOLENOID VALVE FRONT:
      Fig 1: Identifying Height Control Solenoid Valve Front Connector Terminals
      GTY143968Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Measure the resistance according to the values in the table below.

        Standard resistance (RH): (C1737/31)

        Tester Connection Specified Condition
        2 (E) - 3 (RH+) 12 +- 2 Ω

        Standard resistance (LH): (C1738/32)

        Tester Connection Specified Condition
        1 (LH+) - 2 (E) 12 +- 2 Ω
      3. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        RH: (C1737/31)

        Battery Positive Battery Negative
        3 (RH+) 2 (E)
        LH: (C1738/32)

        Battery Positive Battery Negative
        1 (LH+) 2 (E)

        OK

        It should make an operating sound (click).

        Result

        Result Proceed to
        OK A
        NG B

        HINT: 

        When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 1.

    2. HEIGHT CONTROL SOLENOID VALVE REAR:
      Fig 2: Identifying Height Control Solenoid Valve Rear Connector Terminals
      GTY138060Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Measure the resistance according to the values in the table below.

        Standard resistance (RH): (C1739/33)

        Tester Connection Specified Condition
        1 (RH+) - 2 (E) 12 +- 2 Ω

        Standard resistance (LH): (C1740/34)

        Tester Connection Specified Condition
        2 (E) - 3 (LH+) 12 +- 2 Ω

        Standard resistance

        12 +- 2 Ω

      3. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        RH: (C1739/39)

        Battery Positive Battery Negative
        1 (RH+) 2 (E)
        LH: (C1740/34)

        Battery Positive Battery Negative
        3 (LH+) 2 (E)

        OK

        It should make an operating sound (click).

        Result

        Result Proceed to
        OK A
        NG C

        HINT: 

        When a malfunction is found in the front solenoid valve, replace the height control valve sub-assembly No. 2.

    C → REPLACE HEIGHT CONTROL VALVE SUB-ASSEMBLY NO. 2 

    B → REPLACE HEIGHT CONTROL VALVE SUB-ASSEMBLY NO. 1 

    A: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - HEIGHT CONTROL SOLENOID VALVE) 
    1. Disconnect the suspension control ECU S14 connector.
      Fig 3: Identifying Suspension Control ECU S14 Connector
      GTY154736Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the values in the table below.

      Standard resistance (Front RH): (C1737/31)

      Tester Connection Specified Condition
      S14-9 (SLFR) - H14-3 (RH+) Below 1 Ω
      S14-9 (SLFR) - Body ground 10 kΩ or higher

      Standard resistance (Front LH): (C1738/32)

      Tester Connection Specified Condition
      S14-10 (SLFL) - H14-1 (LH+) Below 1 Ω
      S14-10 (SLFL) - Body ground 10 kΩ or higher

      Standard resistance (Rear RH): (C1739/33)

      Tester Connection Specified Condition
      S14-2 (SLRR) - H27-1 (RH+) Below 1 Ω
      S14-2 (SLRR) - Body ground 10 kΩ or higher

      Standard resistance (Rear LH): (C1740/34)

      Tester Connection Specified Condition
      S14-1 (SLRL) - H27-3 (LH+) Below 1 Ω
      S14-1 (SLRL) - Body ground 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL SOLENOID VALVE - BODY GROUND) 
    1. Measure the resistance according to the values in the table below.
      Fig 4: Identifying Height Control Solenoid Valve Connector Terminals
      GTY131534Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance (Front RH): (C1737/31)

      Tester Connection Specified Condition
      H14-3 (RH+) - Body ground Below 1 Ω

      Standard resistance (Front LH): (C1738/32)

      Tester Connection Specified Condition
      H14-1 (LH+) - Body ground Below 1 Ω

      Standard resistance (Rear RH): (C1739/33)

      Tester Connection Specified Condition
      H27-1 (RH+) - Body ground Below 1 Ω

      Standard resistance (Rear LH): (C1740/34)

      Tester Connection Specified Condition
      H27-3 (LH+) - Body ground Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → REPLACE SUSPENSION CONTROL ECU