AIR SUSPENSION SYSTEM, Diagnostic DTC:C1743, C1744

DTC Code DTC Name
C1743 Rear Height Control Solenoid Valve RH Circuit Malfunction
C1744 Rear Height Control Solenoid Valve LH Circuit Malfunction

DESCRIPTION

The No. 2 height control valve independently opens and closes the left and right air passages to the rear pneumatic cylinders according to the signals from the suspension control ECU.

DTC No. DTC Detection Condition Trouble Area
C1743

When either of the following is detected:


  • With the height control valve not activated, an open signal of the height control valve is detected for 1 second or more.

  • With the height control valve activated, a short signal of the height control valve is detected 8 times successively.

  • Height control valve No. 2

  • Wire harness or connector

  • Suspension control ECU
C1744

When either of the following is detected:


  • With the height control valve not activated, an open signal of the height control valve is detected for 1 second or more.

  • With the height control valve activated, a short signal of the height control valve is detected 8 times successively.

  • Height control valve No. 2

  • Wire harness or connector

  • Suspension control ECU

WIRING DIAGRAM

A01NDJEE05

INSPECTION PROCEDURE

Note


  • Before performing troubleshooting, inspect the connectors of related circuits.

  • If DTC C1782 (Power Source Voltage Malfunction) is output at the same time, perform troubleshooting for C1782 first Click here.

  • Before replacing the suspension control ECU, perform all of the following again: 1) symptom simulation Click here; 2) DTC inspection Click here; and 3) Intelligent tester inspection (Data List or Active Test) Click here. If no malfunctions are found in other areas, replace the suspension control ECU.

  • If the suspension control ECU is replaced, the vehicle height offset calibration and registration of vehicle identification information must be performed Click here and Click here

PROCEDURE


  1. INSPECT HEIGHT CONTROL VALVE NO. 2


    1. A01NGF7E24
      Text in Illustration
      *1

      Component without harness connected

      (Height Control Valve No. 2)

      Disconnect the height control valve No. 2 connector.

    2. Measure the resistance according to the values in the table below.

      Standard resistance
      C1743:
      Tester Connection Condition Specified Condition
      1 (RH+) - 2 (E) at 15 to 25°C (59 to 77°F) 10 to 14 Ω
      C1744:
      Tester Connection Condition Specified Condition
      3 (LH+) - 2 (E) at 15 to 25°C (59 to 77°F) 10 to 14 Ω

    3. Check the RH valve (C1743).


      1. Connect a positive (+) lead from the battery to terminal 1 (RH+) and a negative (-) lead to terminal 2 (E).

      2. Check the operating sound of the height control valve No. 2.

        OK
        It makes an operating sound (click).

    4. Check the LH valve (C1744).


      1. Connect a positive (+) lead from the battery to terminal 3 (LH+) and a negative (-) lead to terminal 2 (E).

      2. Check the operating sound of the height control valve No. 2.

        OK
        It makes an operating sound (click).

    NG

    REPLACE HEIGHT CONTROL VALVE NO. 2 Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (HEIGHT CONTROL VALVE NO.2 - ECU AND BODY GROUND)


    1. Disconnect the A55 ECU connector.

    2. Disconnect the Q1 height control valve No. 2 connector.

    3. A01NDQYE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Height Control Valve No. 2)
      *2

      Rear view of wire harness connector

      (to Suspension Control ECU)

      Measure the resistance according to the values in the table below.

      Standard resistance
      C1743:
      Tester Connection Condition Specified Condition
      A55-16 (SLRR) - Q1-1 (RH+) Always Below 1 Ω
      A55-16 (SLRR) - Body ground Always 10 kΩ or higher
      Q1-2 (E) - Body ground Always Below 1 Ω
      C1744:
      Tester Connection Condition Specified Condition
      A55-15 (SLRL) - Q1-3 (LH+) Always Below 1 Ω
      A55-15 (SLRL) - Body ground Always 10 kΩ or higher
      Q1-2 (E) - Body ground Always Below 1 Ω
      Result
      Condition Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    B

    REPLACE SUSPENSION CONTROL ECU (for RHD) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE SUSPENSION CONTROL ECU (for LHD) Click here