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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 C1742/42: Height Control Compressor Circuit >> Procedure

DTC C1742/42: Height Control Compressor Circuit: Procedure

  1. RECONFIRM DTC 
    1. Check if DTC C1741/41 is output. Refer to DTC CHECK / CLEAR .

      OK

      DTC C1741/41 is output.

      Result

      Result Proceed to
      DTC C1741/41 is output. A
      Other DTC is output B

    NG → REPAIR CIRCUIT INDICATED BY OUTPUT CODE 

    OK: Go to next step 

  2. INSPECT HEIGHT CONTROL COMPRESSOR 
    1. Disconnect the height control compressor motor connector.
      Fig 1: Identifying Height Control Compressor Motor Connector Terminals
      GTY154734Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Check the operating sound of the compressor motor when battery positive voltage is applied to the terminals.
      Battery Positive Battery Negative
      1 (B) 2 (L)

      OK

      Compressor motor operates.

      NOTE:
      • Do not operate the height control compressor assembly 60 seconds. or more.
      • Since a short and a lock-up inside the height control compressor assembly causes enormous current to flow, stop operation immediately when it does not rotate.

      HINT: 

      When a malfunction is found in the height control compressor motor, replace the height control compressor assembly.

    NG → REPLACE CONTROL COMPRESSOR ASSEMBLY 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - HEIGHT CONTROL COMPRESSOR MOTOR) 
    1. Connect the height control compressor motor connector.
      Fig 2: Identifying Suspension Control ECU S14 Connector
      GTY133407Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the suspension control ECU S14 connector.
    3. Measure the resistance according to the values in the table below.

      Standard resistance

      Tester Connection Specified Condition
      S14-25 (RM+) - S14-26 (RM-) 6.4 to 7.4 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL COMPRESSOR MOTOR - BODY GROUND) 
    1. Measure the resistance according to the values in the table below.
      Fig 3: Identifying Height Control Compressor Motor Connector Terminals
      GTY154808Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard resistance

      Tester Connection Specified Condition
      2 (L) - Body ground Below 1 Ω

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL COMPRESSOR MOTOR - AIR SUS RELAY) 
    1. Disconnect the AIR SUS relay from the engine room R/B.
      Fig 4: Identifying Height Control Compressor Motor Connector Terminals
      GTY134821Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance according to the values in the table below.

      Standard resistance

      Tester Connection Specified Condition
      1 (B) - 3 (for AIR SUS relay) Below 1 Ω
      1 (B) - Body ground 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (AIR SUS RELAY - AIR SUS FUSE) 
    1. Measure the voltage according to the values in the table below.
      Fig 5: Identifying AIR SUS Relay Connector Terminals
      GTY131202Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard voltage

      Tester Connection Specified Condition
      5 (for AIR SUS relay) - Body ground 11 to 14 V

      Result

      Result Proceed to
      OK A
      (When using Techstream)
      (Referece)
      B
      (When not using Techstream)
      NG C

    C → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    B → See step   8 

    A: Go to next step 

  7. INSPECT HEIGHT CONTROL SOLENOID VALVE 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to the 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 a continuity (will vibrate).

      OK

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

    OK → See step   9 

    NG: Go to next step 

  8. INSPECT HEIGHT CONTROL SOLENOID VALVE 
    1. HEIGHT CONTROL SOLENOID VALVE FRONT RH:
      Fig 6: Identifying Height Control Solenoid Valve Front RH Connector Terminals
      GTY155210Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        Tester Connection
        Battery Positive Battery Negative
        3 (RH+) 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 FRONT LH:
      Fig 7: Identifying Height Control Solenoid Valve Front LH Connector Terminals
      GTY155211Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        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.

    3. HEIGHT CONTROL SOLENOID VALVE REAR RH:
      Fig 8: Identifying Height Control Solenoid Valve Rear RH Connector Terminals
      GTY138490Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        Battery Positive Battery Negative
        1 (RH+) 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 rear solenoid valve, replace the height control valve sub-assembly No. 2.

    4. HEIGHT CONTROL SOLENOID VALVE REAR LH:
      Fig 9: Identifying Height Control Solenoid Valve Rear LH Connector Terminals
      GTY155212Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. Disconnect the height control solenoid valve connector.
      2. Check the operating sound of the height control solenoid valve when positive battery voltage is applied to the terminals.
        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 rear 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 

  9. INSPECT EXHAUST SOLENOID VALVE 
    1. Disconnect the exhaust solenoid valve connector.
      Fig 10: Identifying Exhaust Solenoid Valve Terminals
      GTY140361Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Check the operating sound of the exhaust solenoid valve when positive battery voltage is applied to the terminals.
      Battery Positive Battery Negative
      1 (SLEX) 2 (GND)

      OK

      It should make an operating sound (click).

      HINT: 

      When a malfunction is found in the exhaust solenoid valve, replace the height control compressor assembly.

      Result

      Result Proceed to
      OK A
      (When using Techstream)
      (Referece)
      B
      (When not using Techstream)
      NG C

    C → REPLACE HEIGHT CONTROL COMPRESSOR ASSEMBLY 

    B → See step   11 

    A: Go to next step 

  10. INSPECT TANK SOLENOID VALVE 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to the 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
      Low Pressure Tank Solenoid Turn tank solenoid valve / ON or OFF Operation of solenoid (clicking sound) can be heard
    4. Check whether the tank solenoid valve has a continuity (will vibrate).

      OK

      The solenoid makes sound, and the tank solenoid valve has a continuity (will vibrate).

    OK → See step   12 

    NG → REPLACE PNEUMATIC W/TUBE TANK ASSEMBLY 

  11. INSPECT TANK SOLENOID VALVE 
    1. Disconnect the exhaust solenoid valve connector.
      Fig 11: Identifying Tank Solenoid Valve Connector Terminals
      GTY123136Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Check the operating sound of the tank solenoid valve when positive battery voltage is applied to the terminals.
      Battery Positive Battery Negative
      1 (SLLO) 2 (GND)

      OK

      The solenoid makes sound, and the tank solenoid valve has a continuity (will vibrate).

      HINT: 

      When a malfunction is found in the tank solenoid valve, replace the pneumatic tank assembly.

    NG → REPLACE PNEUMATIC W/TUBE TANK ASSEMBLY 

    OK: Go to next step 

  12. INSPECT FOR CLOGGED AIR TUBE 
    1. Check visually for a clog, damage or breakage on the air tube. Refer to ON-VEHICLE INSPECTION .

    NG → REPAIR OR REPLACE AIR TUBE 

    OK → REPLACE SUSPENSION CONTROL ECU 

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