AUTOMATIC TRANSMISSION (DIAGNOSTICS)(4AT) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0758 SHIFT SOLENOID “B” ELECTRICAL

DTC DETECTING CONDITION:

Output signal circuit of 2-4 brake duty solenoid is open or shorted.

TROUBLE SYMPTOM:

Excessive shift shock

WIRING DIAGRAM:

• FF model

• AWD model

STEPCHECKYESNO

1.CHECK HARNESS CONNECTOR BETWEEN TCM AND TRANSMISSION.

1) Turn the ignition switch to OFF.

2) Disconnect the connectors from TCM and transmission.

3) Measure the resistance of harness between TCM connector and transmission connector.

Connector & terminal

(B54) No. 4 — (B11) No. 3:

Is the resistance less than 1 Ω?

Repair the open circuit of harness between TCM and transmission connector.

2.CHECK HARNESS CONNECTOR BETWEEN TCM AND CHASSIS GROUND.

Measure the resistance of harness between TCM connector and chassis ground.

Connector & terminal

(B54) No. 4 — Chassis ground:

Is the resistance 1 MΩ or more?

Repair the short circuit of harness between TCM and transmission connector.

3.CHECK 2-4 BRAKE DUTY SOLENOID.

Measure the resistance between transmission connector terminals.

Connector & terminal

(T4) No. 3 — No. 20:

Is the resistance between 2.0 — 6.0 Ω?

4.CHECK OUTPUT SIGNAL OF TCM.

1) Connect all connectors.

2) Connect the Subaru Select Monitor to data link connector.

3) Start the engine.

4) Run the Subaru Select Monitor.

5) Warm up the transmission until the ATF temperature exceeds approximately 80°C (176°F).

6) Stop the engine.

7) Turn the ignition switch to ON.

8) Shift the select lever to “N”, and depress the accelerator pedal.

9) Read the data of “Brake Clutch Duty Ratio” using Subaru Select Monitor.

Is the measured value 100%?

5.CHECK OUTPUT SIGNAL OF TCM.

1) Shift the select lever to “D” range. (2nd gear in manual mode).

2) Read the data of “Brake Clutch Duty Ratio” using Subaru Select Monitor.

Is the measured value 0%?

Check the harnesses or connectors between TCM and transmission, and repair the defective part.

6.CHECK POOR CONTACT.

Is there poor contact of 2-4 brake duty solenoid circuit?

Repair the poor contact.

Replace the TCM.

7.CHECK 2-4 BRAKE DUTY SOLENOID (IN TRANSMISSION).

1) Remove the transmission connector from bracket.

2) Drain the automatic transmission fluid.

CAUTION:

Do not drain ATF until it cools down.

3) Remove the oil pan.

4) Disconnect the connector from the 2-4 brake duty solenoid.

5) Measure the resistance of harness between 2-4 brake duty solenoid connector and transmission ground.

Connector & terminal

FF model

(AT3) No. 6 — Transmission ground:

AWD model

(AT2) No. 8 — Transmission ground:

Is the resistance between 2.0 — 6.0 Ω?

Replace the control valve body.

8.CHECK HARNESS CONNECTOR BETWEEN 2-4 BRAKE DUTY SOLENOID AND TRANSMISSION.

Measure the resistance of harness between 2-4 brake duty solenoid and transmission connector.

Connector & terminal

FF model

(T4) No. 3 — (AT3) No. 6:

AWD model

(T4) No. 3 — (AT2) No. 8:

Is the resistance less than 1 Ω?

Repair the open circuit of harness between 2-4 brake duty solenoid and transmission connector.

9.CHECK HARNESS CONNECTOR BETWEEN 2-4 BRAKE DUTY SOLENOID AND TRANSMISSION.

Measure the resistance of harness between transmission connector and transmission ground.

Connector & terminal

(T4) No. 3 — Transmission ground:

Is the resistance 1 MΩ or more?

Check the harnesses or connectors between 2-4 brake duty solenoid and transmission, and repair the defective part.

Repair the short circuit of harness between 2-4 brake duty solenoid and transmission connector.