DTC P0756: Shift Solenoid "B" Performance/Stuck Off: Notes

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

• Acceleration is poor during standing start.
• Shift control malfunction

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.

   Besides DTC P0756, is any of the DTCs P0973, P0974, P0976, P0977, P2747 and P2751 displayed?

   Yes:  Perform the diagnosis according to DTCs other than P0756.

   No:  Go to  2.

2. CHECK PRIMARY DOWN SOLENOID (ACTIVE TEST). 
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor, perform forced operation of the primary DOWN 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  5.

   No:  Go to  3.

3. CHECK PRIMARY DOWN 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. 1 - Transmission body:

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

   Yes:  Go to  7.

   No:  Go to  4.

4. CHECK HARNESS. 

   Check the transmission harness. (Open circuit, short circuit to power supply, short circuit to ground, and poor contact)

   Is the check result OK?

   Yes:  Go to  7.

   No:  Repair the harness.

5. CHECK TRANSMISSION FLUID. 
   1. Connect the transmission connector.
   2. Check the amount of ATF. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CVTF>ADJUSTMENT .

   Is the check result OK?

   Yes:  Go to  6.

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

6. 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  7.

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

7. 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:  Go to  8.

   No:  Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

8. CHECK INPUT SIGNAL FOR TCM. 
   1. Set the select lever to "D" range.
   2. Release the brake pedal to stabilize the engine speed and front wheel speed.
   3. Read the data of «Actual Gear Ratio» using Subaru Select Monitor.
      NOTE: Before operation, set SI-DRIVE to I mode.

   Is the «Actual Gear Ratio» 2.0 - 2.4?

   Yes:  Go to  9.

   No:  Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

9. CHECK INPUT SIGNAL FOR TCM. 
   1. Set the select lever to "D" range.
   2. Slowly increase the speed to 40 km/h (25 MPH) and keep to a constant speed.
   3. Read the data of «Actual Gear Ratio» using Subaru Select Monitor.
      NOTE: Before operation, set SI-DRIVE to I mode.

   Is the «Actual Gear Ratio» 0.5 - 0.8?

   Yes:  Go to  10.

   No:  Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

10. DRIVING CHECK BY INSPECTION MODE. 
    1. Turn the ignition switch to OFF.
    2. Perform a drive check based on the "Inspection Mode". Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>INSPECTION MODE .

    Does the AT OIL TEMP light blink and is DTC P0756 displayed?

    Yes:  Replace the transmission assembly. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>AUTOMATIC TRANSMISSION ASSEMBLY .

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