DTC P0846: Transmission Fluid Pressure Sensor/Switch "B" Circuit Range/Performance: Notes

WARNING: This page is about a different variant/trim than selected.

1. -

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Acceleration is poor during standing start.
Shift control malfunction
Engine speed increases abruptly.

Wiring diagram:

CVT control system Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>CVT CONTROL SYSTEM .

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CAUTION:

Before performing diagnosis, record the freeze frame data.
Use 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) (CROSSTREK MODEL)>BASIC DIAGNOSTIC PROCEDURE .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

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

Are DTCs other than P0846 and P1867 displayed?

Yes : Perform the diagnosis according to DTCs other than P0846 and P1867. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DIAGNOSTIC TROUBLE CODE (DTC)>LIST .

No : Go to 2.
CHECK DTC .
Read the DTC of [Transmission] using the Subaru Select Monitor. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DIAGNOSTIC TROUBLE CODE (DTC) .

Besides DTC P0846 and P1867, is DTC P2723 displayed?

Yes : Perform the diagnosis according to DTC P1867. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DIAQNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P1867 TRANSMISSION SECONDARY FLUID PRESSURE .

No : Go to 3.
CHECK INPUT SIGNAL FOR TCM .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, read data of [secondary pressure sensor voltage.] in the [Data Monitor] of [Transmission]. (While shaking the secondary pressure sensor harness) Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DATA MONITOR .
Is [secondary pressure sensor voltage.] 0.39 - 0.61 [V]?

Yes : Go to 11.

No : Go to 4.
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Disconnect the secondary pressure sensor connector.
4. Measure the resistance between TCM connector and secondary pressure sensor connector.
  Connector & terminal
  
  (T10) No. 2 - (AT6) No. 3:
  
  (T10) No. 5 - (AT6) No. 2:
  
  (T10) No. 33 - (AT6) No. 1:
Is the resistance less than 1 Ω?

Yes : Go to 5.

No : Repair the open circuit of harness.
CHECK HARNESS .
Measure the resistance between TCM connectors.

Connector & terminal

(T10) No. 2 - (T10) No. 33:

(T10) No. 5 - (T10) No. 2:

(T10) No. 33 - (T10) No. 5:

Is the resistance 1 MΩ or more?

Yes : Go to 6.

No : Repair the short circuit of harness.
CHECK HARNESS .
Measure the resistance between TCM connector and transmission body.

Connector & terminal

(T10) No. 2 - Transmission body:

(T10) No. 5 - Transmission body:

(T10) No. 33 - Transmission body:

Is the resistance 1 MΩ or more?

Yes : Go to 7.

No : Repair the short circuit of harness.
CHECK POWER SUPPLY FOR SECONDARY PRESSURE SENSOR .
1. Turn the ignition switch to ON.
2. Measure the voltage between TCM connectors.
  Connector & terminal
  
  (T10) No. 33 (+) - (T10) No. 2 (-):
Is the voltage 4.6 - 5.4 V?

Yes : Go to 8.

No : Check for poor contact of connector, and if no fault is found, replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>TRANSMISSION CONTROL MODULE (TCM) .
CHECK POWER SUPPLY FOR SECONDARY PRESSURE SENSOR .
1. Turn the ignition switch to OFF.
2. Connect the secondary pressure sensor connector.
3. Turn the ignition switch to ON.
4. Measure the voltage between TCM connectors.
  Connector & terminal
  
  (T10) No. 33 (+) - (T10) No. 2 (-):
Is the voltage 4.6 - 5.4 V?

Yes : Go to 9.

No : Replace the secondary pressure sensor. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>SECONDARY PRESSURE SENSOR .
CHECK SECONDARY PRESSURE SENSOR OUTPUT .
Measure the voltage between TCM connectors.

Connector & terminal

(T10) No. 5 (+) - (T10) No. 2 (-):

Is the voltage 0.39 - 0.61 V?

Yes : Check for poor contact of connector, and if no fault is found, replace the TCM. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>TRANSMISSION CONTROL MODULE (TCM) .

No : Go to 10.
CHECK CONNECTOR .
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Disconnect the secondary pressure sensor connector.
4. Check the TCM connector (T10) and the secondary pressure sensor connector (AT6).
Is the check result OK?

Yes : Go to 11.

No : Repair the connector, or replace harness.
CHECK TRANSMISSION FLUID .
1. Connect all connectors.
2. Check the amount of ATF. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>CVTF>INSPECTION .
Is the check result OK?

Yes : Go to 12.

No : Adjust the amount of ATF. Go to 12.
CHECK INPUT SIGNAL FOR TCM .
1. Using the Subaru Select Monitor, perform the clear memory of [Transmission]. Ref. to COMMON (DIAG)>CLEAR MEMORY .
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. Set the select lever to "D" range.
6. Drive at 2 km/h or more.
7. Shift the select lever to "P" range.
8. Stabilize the engine speed at idle.
9. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DATA MONITOR .
Is [Actual Secondary Pressure] 0.5 - 1.5 [MPa]?

Yes : Go to 13.

No : Replace the secondary pressure sensor. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>SECONDARY PRESSURE SENSOR .
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) (CROSSTREK 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 12 0.2 [MPa] or more?

Yes : Go to 14.

No : Replace the secondary pressure sensor. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR580 CROSSTREK)>SECONDARY PRESSURE SENSOR .

CHECK FREEZE FRAME DATA .

Turn the ignition switch to OFF.
Check the recorded freeze frame data for DTC P1867. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK 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.

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NOTE: Symptom that the DTC P1867 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 CROSSTREK)>TRANSMISSION ASSEMBLY .

No : Go to 15.

CHECK TCM INPUT SIGNAL (STALL TEST) .
1. Lift up the vehicle.
2. Start the engine.
3. Apply the parking brake.
4. Set the select lever to "D" range.
5. Depress the brake pedal firmly.
6. Slowly open the accelerator fully, and stabilize the engine speed.
7. Using the Subaru Select Monitor, read data of [Actual Secondary Pressure] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS) (CROSSTREK MODEL)>DATA MONITOR .
Is the [Actual Secondary Pressure] 6.0 [MPa] or more?

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

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