AIR SUSPENSION SYSTEM, Diagnostic DTC:C1748

DTC Code DTC Name
C1748 Low Pressure Tank Valve

DESCRIPTION

The low pressure tank valve built into the pneumatic tank assembly opens to store and discharge air in the pneumatic tank according to the signal from the suspension control ECU.

DTC No. DTC Detection Condition Trouble Area
C1748

When either of the following is detected:


  • With the low pressure tank valve not activated, an open signal of the low pressure tank valve is detected for 1 second or more.

  • With the low pressure tank valve activated, a short signal of the low pressure tank valve is detected 8 times successively.

  • Low pressure tank valve

  • Wire harness or connector

  • Suspension control ECU

WIRING DIAGRAM

A01NHA6E03

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 PNEUMATIC W/TUBE TANK ASSEMBLY (LOW PRESSURE TANK VALVE)


    1. Turn the power switch off.

    2. A01NHQXE07
      Text in Illustration
      *1

      Component without harness connected

      (Low Pressure Tank Valve)

      Disconnect the low pressure tank valve connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      2 (B) - 1 (L) 15 to 25°C (59 to 77°F) 10 to 14 Ω

    4. Inspect if the low pressure tank valve is stuck :


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

      2. Check the operating sound of the low pressure tank valve.

        OK
        It makes an operating sound (click).

    NG

    REPLACE PNEUMATIC W/TUBE TANK ASSEMBLY Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - TANK SOLENOID VALVE)


    1. Turn the power switch off.

    2. Disconnect the A54 ECU connector.

    3. Disconnect the O11 low pressure tank valve connector.

    4. A01NF2KE04
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Low Pressure Tank Valve)
      *2

      Rear view of wire harness connector

      (to Suspension Control ECU)

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

      Standard resistance
      Tester Connection Condition Specified Condition
      O11-2 (B) - A54-20 (SLLO) Always Below 1 Ω
      A54-20 (SLLO) - Body ground Always 10 kΩ or higher
      O11-1 (L) - 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