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DTC P2758: Torque Converter Clutch Pressure Control Solenoid Control Circuit Stuck On: Notes

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

1. - 

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

The engine stalls when the vehicle is stopped.

Wiring diagram: 

CVT control system Ref. to WIRING SYSTEM>CVT CONTROL SYSTEM>WIRING DIAGRAM

G14613613Courtesy of SUBARU OF AMERICA, INC.
CAUTION:
  1. CHECK DTC  .

    Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

    Is only DTC P2758 displayed?

    Yes  : Go to  3.

    No  : Go to  2.

  2. CHECK DTC  .

    Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

    Is DTC P2763 or P2764 displayed?

    Yes  : Perform the diagnosis according to DTC P2763 or P2764. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST 

    No  : Go to  3.

  3. CHECK LOCK-UP DUTY SOLENOID (ACTIVE TEST)  .
    1. Turn the ignition switch to ON.
    2. Using the Subaru Select Monitor, perform the active test of the lock-up duty solenoid. Ref. to TRANSMISSION (DIAGNOSTICS)>ACTIVE TEST 

    Does the indication of 0 → 50% appear repeatedly during the active test, and does operating sound emit during indicating 50%?

    Yes  : Go to  9.

    No  : Go to  4.

  4. CHECK LOCK-UP DUTY SOLENOID  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the transmission connector.
    3. Measure the resistance between transmission connector and transmission body.

      Connector & terminal 

      (T1) No. 8 - Transmission body:

    Is the resistance approximately 10 - 14.2 Ω? (When cold)

    Yes  : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY

    No  : Go to  5.

  5. CHECK HARNESS  .
    1. Disconnect the TCM connector.
    2. Measure the resistance between TCM connector and transmission connectors.

      Connector & terminal 

      (B67) No. 15 - (E34) No. 8:

    Is the resistance less than 1 Ω?

    Yes  : Go to  6.

    No  : Repair the open circuit of harness.

  6. CHECK HARNESS  .

    Measure the resistance between TCM connector and transmission body.

    Connector & terminal 

    (B67) No. 15 - Transmission body:

    Is the resistance 1 MΩ or more?

    Yes  : Go to  7.

    No  : Repair the short circuit of harness.

  7. CHECK HARNESS  .
    CAUTION:

    Start work after ATF cools down. 

    1. Remove the transmission oil pan.
    2. Disconnect the control valve body connector.
    3. Measure the resistance between transmission connector and control valve body connector.

      Connector & terminal 

      (T1) No. 8 - (T11) No. 2:

    Is the resistance less than 1 Ω?

    Yes  : Go to  8.

    No  : Repair the open circuit of harness.

  8. CHECK HARNESS  .

    Measure the resistance between transmission connector and control valve body.

    Connector & terminal 

    (T11) No. 2 - Control valve body:

    Is the resistance 1 MΩ or more?

    Yes  : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY

    No  : Repair the short circuit of harness.

  9. CHECK TRANSMISSION FLUID  .
    1. Connect all connectors.
    2. Check the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>INSPECTION

    Is the check result OK?

    Yes  : Go to  10.

    No  : Adjust the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>INSPECTION Go to  10.

  10. CHECK TRANSMISSION FLUID  .

    Check the condition of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>REPLACEMENT

    Is the check result OK?

    Yes  : Return ATF. Go to  11.

    No  : Follow the "Corrective action" of ATF (CVTF) "CONDITION CHECK". Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>REPLACEMENT Go to  11.

  11. CHECK ENGAGEMENT CONDITION OF LOCK-UP CLUTCH  .
    1. Start the engine.
    2. Warm up until the ATF temperature exceeds 50°C (122°F).
    3. Depress the brake pedal, and shift the select lever to "D" range.

    Are there any vibrations due to engine stall or engine speed drop?

    Yes  : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY Go to  13.

    No  : Go to  12.

  12. CHECK INPUT SIGNAL FOR TCM  .
    1. Lift up the vehicle.
    2. Start the engine.
    3. Warm up until the ATF temperature reaches to 40 - 70°C (104 - 158°F).
    4. Depress the brake pedal, and shift the select lever to "D" range.
    5. Shift the select lever to "P" range.
    6. Stabilize the engine speed at idle.
    7. Using the Subaru Select Monitor, read data of [Actual line press.] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS)>DATA MONITOR 

    Is [Actual line press.] 0.5 - 1.5 MPa?

    Yes  : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY Go to  13.

    No  : Perform the diagnosis according to DTC P0867. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0867 TRANSMISSION FLUID PRESSURE 

  13. DRIVING CHECK FOR LOCK-UP CONDITION  .
    1. Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY
    2. Turn the ignition switch to OFF.
    3. Start the engine.
    4. Warm up until the ATF temperature exceeds 50°C.
    5. Depress the brake pedal, and shift the select lever to "D" range.
    6. Shift the select lever to "P" range.
    7. Turn the ignition switch to OFF.
    8. Start the engine.
    9. Perform step  5 - step  6 again.
    10. Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) 

    Does the AT OIL TEMP light blink and is DTC P2758 displayed? Or are there any vibrations due to engine stall or engine speed drop?

    Yes  : Replace the torque converter assembly, and perform step  13 again. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TORQUE CONVERTER If the replacement of the torque converter assembly does not eliminate the malfunction, replace the transmission assembly and perform step  13 again. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION ASSEMBLY

    No  : Current condition is normal. It is possible that temporary failure occurred to the energization status or to the hydraulic circuit.

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