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

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 Refer to WIRING SYSTEM>CVT CONTROL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC. 

   Read the DTC using Subaru Select Monitor.

   Is a DTC other than DTC P2758 displayed?

   Yes:  Perform the diagnosis according to DTCs other than P2758.

   No:  Go to  2.

2. CHECK LOCK-UP DUTY SOLENOID (ACTIVE TEST). 
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, perform forced operation of the lock-up duty solenoid. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>ACTIVE TEST .

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

   Yes:  Go to  8.

   No:  Go to  3.

3. 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 

      (T4) No. 2 - Transmission body:

   Is the resistance approx. 10 - 13.5 Ω? (when cold)

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

   No:  Go to  4.

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

      Connector & terminal 

      (B54) No. 15 - (B11) No. 2:

   Is the resistance less than 1 Ω?

   Yes:  Go to  5.

   No:  Repair the open circuit of harness.

5. CHECK HARNESS. 

   Measure the resistance between TCM connector and transmission body.

   Connector & terminal 

   (B54) No. 15 - Transmission body:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  6.

   No:  Repair the short circuit of harness.

6. 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 

      (T4) No. 2 - (T11) No. 2:

   Is the resistance less than 1 Ω?

   Yes:  Go to  7.

   No:  Repair the open circuit of harness.

7. 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. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY .

   No:  Repair the short circuit of harness.

8. CHECK TRANSMISSION FLUID. 
   1. Connect all connectors.
   2. Check the amount of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>ADJUSTMENT .

   Is the check result OK?

   Yes:  Go to  9.

   No:  Adjust the amount of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>ADJUSTMENT .

9. CHECK TRANSMISSION FLUID. 

   Check the condition of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>CONDITION CHECK .

   Is the check result OK?

   Yes:  Go to  10.

   No:  Check according to the "Corrective action" of ATF (CVTF) "CONDITION CHECK". Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>CONDITION CHECK .

10. 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. Read the data of «Actual Secondary Pressure» using Subaru Select Monitor.

    Is the «Actual Secondary Pressure» 0.5 - 1.5 MPa?

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

    Go to  11.

    No:  Perform the diagnosis according to DTC P0841. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0841 TRANSMISSION FLUID PRESSURE SENSOR/SWITCH "A" CIRCUIT RANGE/PERFORMANCE .

11. DRIVING CHECK FOR LOCK-UP CONDITION. 
    1. Perform the Clear Memory Mode. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>CLEAR MEMORY MODE .
    2. Turn the ignition switch to OFF.
    3. Start the engine.
    4. Warm up until the ATF temperature exceeds 50°C.
    5. Drive the vehicle for one minute or more while keeping such constant speed that «Lock Up Duty Ratio» is 0%, and «Front Wheel Speed» is 5 km/h (3 MPH) or less, which are displayed on the Subaru Select Monitor.
    6. Turn the ignition switch to OFF.
    7. Start the engine.
    8. Perform the procedure in step  5 again.
    9. Read the DTC using Subaru Select Monitor.

    Does the AT OIL TEMP light blink and is DTC P2758 displayed? Or does the engine stall?

    Yes:  Replace the torque converter assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TORQUE CONVERTER ASSEMBLY .

    No:  Current condition is normal. It is possible that temporary poor contact occurs.