ACTIVE HEIGHT CONTROL SUSPENSION, Diagnostic DTC:C1736, C1737

DTC Code DTC Name
C1736 Front Suspension Control Valve RH Malfunction
C1737 Front Suspension Control Valve LH Malfunction

DESCRIPTION

In order to decrease roll angle/pitch angle, the suspension control ECU turns the spring rate switching valve in the front suspension control valve off/on to change the fluid lines when the acceleration sensor or yaw rate sensor signal is input into the suspension control ECU. Normally, the spring rate switching valve is open.

DTC Code Detection Condition Trouble area
C1736

When either of the following is detected:


  • With the spring rate switch valve RH not activated, an open signal of the spring rate switch valve RH is detected for 1 second or more.

  • With the spring rate switch valve RH activated, a short signal of the spring rate switch valve RH is detected 8 times successively.

  • Harness or connector

  • Front suspension control valve RH (Front spring rate switching valve RH)

  • Suspension control ECU

  • No. 1 height control valve
C1737

When either of the following is detected:


  • With the spring rate switch valve LH not activated, an open signal of the spring rate switch valve LH is detected for 1 second or more.

  • With the spring rate switch valve LH activated, a short signal of the spring rate switch valve LH is detected 8 times successively.

  • Harness or connector

  • Front suspension control valve LH (Front spring rate switching valve LH)

  • Suspension control ECU

  • No. 1 height control valve

WIRING DIAGRAM

A0158ZFE01

INSPECTION PROCEDURE

Note


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

  • If the suspension control ECU or height control sensor is replaced, the vehicle height offset calibration must be performed Click here.

Tech Tips

Power is supplied to the front suspension control valve and No. 1 height control valve from the suspension control ECU. If a short occurs in the power supply circuit in the No. 1 height control valve, DTC C1736 and/or C1737 will be stored. In this case, DTC C1741, C1742, C1743, C1744, C1753, C1754 and/or C1755 will also be stored.

PROCEDURE


  1. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (FRONT SPRING RATE SWITCHING VALVE)


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the tester on.

    3. Select the Active Test mode on the intelligent tester.

    4. Check the operation of the front spring rate switching valve solenoid when operating the solenoid with the intelligent tester.

      AHC
      Tester Display Test Part Control Range Diagnostic Note
      FR Gas Spring Switch Valve Front spring rate switching valve RH ON or OFF When the FR Gas Spring Switch Valve item of the Active Test is operated, the FR Gas Spring Switch Valve item of the Data List changes to ON/OFF.
      FL Gas Spring Switch Valve Front spring rate switching valve LH ON or OFF When the FL Gas Spring Switch Valve item of the Active Test is operated, the FL Gas Spring Switch Valve item of the Data List changes to ON/OFF.
      OK
      The front spring rate switching valve operates.

    NG

    CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - FRONT SUSPENSION CONTROL VALVE) Click here

    OK

  2. RECONFIRM DTC OUTPUT


    1. Clear the DTCs Click here.

    2. Perform a road test.

    3. Check for DTCs.

      Result
      Result Proceed to
      DTC is output A
      DTC is not output B

    B

    USE SIMULATION METHOD TO CHECK Click here

    A

    REPLACE SUSPENSION CONTROL ECU Click here

  3. CHECK HARNESS AND CONNECTOR (SUSPENSION CONTROL ECU - FRONT SUSPENSION CONTROL VALVE)


    1. Disconnect the N10*1 and/or N12*2 front suspension control valve connector.

      Tech Tips

      *1: for RH

      *2: for LH

    2. Disconnect the K36 ECU connector.

      A015DPBE01

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K36-11 (CRFR) - N10-1 (CRFR) Always Below 1 Ω
      K36-11 (CRFR) - Body ground Always 10 kΩ or higher
      K36-23 (CRFL) - N12-1 (CRFL) Always Below 1 Ω
      K36-23 (CRFL) - Body ground Always 10 kΩ or higher
      K36-1 (SLB) - N10-2 (SLB) Always Below 1 Ω
      K36-1 (SLB) - N12-2 (SLB) Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (BODY GROUND BETWEEN ECU - FRONT SUSPENSION CONTROL VALVE)


    1. Disconnect the K36 ECU connector.

    2. Disconnect the N10*1 and/or N12*2 front suspension control valve connector.

      Tech Tips

      *1: for RH

      *2: for LH

    3. A015BDXE04

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K36-1 (SLB) - Body ground Always 10 kΩ or higher

    NG

    CHECK HARNESS AND CONNECTOR (BODY GROUND BETWEEN ECU - NO. 1 HEIGHT CONTROL VALVE) Click here

    OK

  5. INSPECT FRONT SUSPENSION CONTROL VALVE


    1. Connect the N10 and/or N12 front suspension control valve connector.

    2. A015BDXE03

      Disconnect the K36 ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K36-11 (CRFR) - K36-1 (SLB) at 20°C (68°F) 4.58 to 5.02 Ω
      K36-23 (CRFL) - K36-1 (SLB) at 20°C (68°F) 4.58 to 5.02 Ω

    NG

    REPLACE FRONT SUSPENSION CONTROL VALVE Click here

    OK

    REPLACE SUSPENSION CONTROL ECU Click here

  6. CHECK HARNESS AND CONNECTOR (BODY GROUND BETWEEN ECU - NO. 1 HEIGHT CONTROL VALVE)


    1. Disconnect the N4 No. 1 height control valve connector.

    2. Disconnect the K36 ECU connector.

    3. A015BDXE04

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K36-1 (SLB) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK HARNESS AND CONNECTOR (NO. 1 HEIGHT CONTROL VALVE - SUSPENSION CONTROL ECU)


    1. Disconnect the N4 No. 1 height control valve connector.

    2. Disconnect the K36 ECU connector.

      A0156HZE01

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K36-1 (SLB) - N4-6 (SLB) Always Below 1 Ω
      K36-7 (SLFR) - N4-4 (SLFR) Always Below 1 Ω
      K36-7 (SLFR) - Body ground Always 10 kΩ or higher
      K36-8 (SLFL) - N4-3 (SLFL) Always Below 1 Ω
      K36-8 (SLFL) - Body ground Always 10 kΩ or higher
      K36-9 (SLRR) - N4-1 (SLRR) Always Below 1 Ω
      K36-9 (SLRR) - Body ground Always 10 kΩ or higher
      K36-10 (SLAC) - N4-7 (AHC-) Always Below 1 Ω
      K36-10 (SLAC) - Body ground Always 10 kΩ or higher
      K36-22 (SLRL) - N4-2 (SLRL) Always Below 1 Ω
      K36-22 (SLRL) - Body ground Always 10 kΩ or higher
      K36-29 (SLRG) - N4-5 (SLRG) Always Below 1 Ω
      K36-29 (SLRG) - Body ground Always 10 kΩ or higher
      K36-30 (SLFG) - N4-8 (SLFG) Always Below 1 Ω
      K36-30 (SLFG) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE NO. 1 HEIGHT CONTROL VALVE Click here