DTC P0746: Pressure Control Solenoid "A" Performance/Stuck Off: Notes

WARNING: This page is about a different car, the 2021 Subaru Impreza. 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:

Acceleration is poor during standing start.
Shift control malfunction

Wiring diagram:

CVT control system Ref. to WIRING SYSTEM (IMPREZA MODEL)>CVT CONTROL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Before performing diagnosis, record the freeze frame data.
Use the check board when measuring the TCM terminal voltage and resistance.
After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>BASIC DIAGNOSTIC PROCEDURE .

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

Besides DTC P0746 and P0867, is DTC P0842, P0843, P0962, or P0963 displayed?

Yes: Perform the diagnosis according to DTCs other than P0746 and P0867. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

No: Go to 2.
CHECK SECONDARY SOLENOID (ACTIVE TEST) .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, perform the active test for secondary solenoid. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>ACTIVE TEST .
Does the indication of 0 → 500 mA appear repeatedly during the active test, and does operating sound emit during indicating 500 mA?

Yes: Go to 5.

No: Go to 3.
CHECK SECONDARY SOLENOID .
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Measure the resistance between TCM connector and transmission body.
  Connector & terminal
  
  (T10) No. 32 - Transmission body:
Is the resistance approximately 4.8 - 8.4 Ω? (When cold)

Yes: Go to 7.

No: Go to 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.
CHECK TRANSMISSION FLUID .
Check the condition of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>CONDITION CHECK .

Is the check result OK?

Yes: Return ATF. Go to 6.

No: Replace the ATF. Go to 6.
CHECK TRANSMISSION FLUID .
1. Connect the TCM connector.
2. Check the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>ADJUSTMENT .
Is the check result OK?

Yes: Go to 7.

No: Adjust the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CVTF>ADJUSTMENT . Go to 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 move the select lever to each range at an interval of five seconds.
  NOTE: Move the select lever in the following order: "P" → "R" → "N" → "D" → "N" → "R" → "P".
5. Stabilize the engine speed at idle.
6. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
Is [Actual Secondary Pressure] 0.5 - 1.5 MPa?

Yes: Go to 8.

No: Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CONTROL VALVE BODY .
CHECK INPUT SIGNAL FOR TCM .
1. Shift the select lever to "P" range.
2. Keep the engine speed at 3, 000 rpm.
3. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
Is [Actual Secondary Pressure] 1.5 - 2.5 MPa? Is the difference between the actual oil pressure and the value measured in Step 7 0.2 MPa or more?

Yes: Go to 9.

No: Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CONTROL VALVE BODY .

CHECK FREEZE FRAME DATA .

Turn the ignition switch to OFF.
Check the recorded freeze frame data for DTC P0867. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>FREEZE FRAME DATA .

Apply the values of [Actual Secondary Pressure] and [Secondary Actual Current] recorded in the freeze frame data onto the graph shown in the following figure, and judge if either low-voltage malfunction or high-voltage malfunction occurs.

Courtesy of SUBARU OF AMERICA, INC.

NOTE: Symptom that the DTC P0746 illuminates can be classified into 2 patterns.

Low-voltage malfunction: detected due to insufficient oil pressure
High-voltage malfunction: detected due to excessive oil pressure

Was the detected symptom low-voltage malfunction?

Yes: Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>AUTOMATIC TRANSMISSION ASSEMBLY .

No: Go to 10.

CHECK TCM INPUT SIGNAL (STALL TEST) .
1. Apply the parking brake.
2. Set the select lever to "D" range.
3. Depress the brake pedal firmly.
4. Slowly open the accelerator fully, and stabilize the engine speed.
5. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (IMPREZA MODEL)>DATA MONITOR .
  CAUTION: Do not perform a stall test for over 5 seconds at a time.
Is the [Actual Secondary Pressure] 6.0 MPa or more?

Yes: Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>CONTROL VALVE BODY .

No: Replace the transmission assembly. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 IMPREZA)>AUTOMATIC TRANSMISSION ASSEMBLY .