DTC P0720: Output Shaft Speed Sensor Circuit: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Shock occurs when selecting shift position.
• Shift control malfunction

Wiring diagram: 

CVT control system Refer to WIRING SYSTEM>CVT CONTROL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK FUSE. 
   1. Turn the ignition switch to OFF.
   2. Remove the fuse (7.5 A) from the fuse holder.
   3. Check the fuse.

   Is the check result OK?

   Yes: Go to  2.

   No: Replace the fuse. If the fuse blows out easily, repair the short circuit of harness.

2. CHECK HARNESS. 
   1. Disconnect the TCM connector.
   2. Remove the self shut relay.
   3. Measure the resistance between TCM connector and relay holder.

      Connector & terminal 

      (B54) No. 25 - (B220) No. 16:

      (B54) No. 8 - (B220) No. 15:

      (B54) No. 24 - (B220) No. 15:

      (B54) No. 40 - (B220) No. 15:

   Is the resistance less than 1 Ω?

   Yes: Go to  3.

   No: Repair the open circuit of harness.

3. CHECK HARNESS. 

   Measure the resistance between TCM connector and chassis ground.

   Connector & terminal 

   (B54) No. 25 - Chassis ground:

   (B54) No. 8 - Chassis ground:

   (B54) No. 24 - Chassis ground:

   (B54) No. 40 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes: Go to  4.

   No: Repair the short circuit of harness.

4. CHECK RELAY POWER SUPPLY. 

   Measure the voltage between relay holder and chassis ground.

   Connector & terminal 

   (B220) No. 14 (+) - Chassis ground (-):

   (B220) No. 17 (+) - Chassis ground (-):

   Is the voltage 10 V or more?

   Yes: Go to  5.

   No: Repair the open or short circuit of harness.

5. CHECK SELF SHUT RELAY. 

   Measure the resistance between self shut relay terminals.

   Terminals 

   No. 16 - No. 17:

   Is the resistance 110 - 140 Ω?

   Yes: Go to  6.

   No: Replace the self shut relay.

6. CHECK SELF SHUT RELAY. 

   Measure the resistance between self shut relay terminals.

   Terminals 

   No. 14 - No. 15:

   Is the resistance 1 MΩ or more?

   Yes: Go to  7.

   No: Replace the self shut relay.

7. CHECK INPUT SIGNAL FOR TCM. 
   1. Connect the TCM connector.
   2. Install the self shut relay.
   3. Read the data of «Control module voltage» using Subaru Select Monitor.

   Is the «Control module voltage» 10 V or more?

   Yes: Current condition is normal. Check for poor contact in connectors or harnesses, and repair the defective part.

   No: Go to  8.

8. CHECK HARNESS. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the TCM connector.
   3. Disconnect the transmission connector.
   4. Measure the resistance between TCM connector and transmission connectors.

      Connector & terminal 

      (B54) No. 12 - (B11) No. 12:

      (B54) No. 42 - (B11) No. 13:

      (B550) No. 20 - (B11) No. 7:

   Is the resistance less than 1 Ω?

   Yes: Go to  9.

   No: Repair the open circuit of harness.

9. CHECK HARNESS. 

   Measure the resistance between TCM connector and chassis ground.

   Connector & terminal 

   (B54) No. 12 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes: Go to  10.

   No: Repair the short circuit of harness.

10. CHECK HARNESS. 

    Measure the resistance between relay holder and fuse holder.

    Connector & terminal 

    (B220) No. 15 - (B550) No. 6:

    Is the resistance less than 1 Ω?

    Yes: Go to  11.

    No: Repair the open circuit of harness.

11. CHECK TRANSMISSION HARNESS. 
    1. Install the fuse.
    2. Connect the TCM connector.
    3. Turn the ignition switch to ON.
    4. Measure the voltage between transmission connector terminals.

       Connector & terminal 

       (B11) No. 7 (+) - Chassis ground (-):

    Is the voltage approx. 10 - 13 V?

    Yes: Go to  12.

    No: Repair the open circuit of harness or poor contact of connector.

12. CHECK INPUT SIGNAL FOR TCM. 
    1. Turn the ignition switch to OFF.
    2. Connect the transmission connector.
    3. Lift up the vehicle.
    4. Start the engine.
    5. Slowly increase the speed to 30 km/h (19 MPH).
    6. Read the data of «Front Wheel Speed» using Subaru Select Monitor.

    Does the value of «Front Wheel Speed» change according to the engine speed?

    Yes: Current condition is normal. Repair the poor contacts of harnesses of front wheel speed sensor and transmission connector.

    No: Go to  13.

13. CHECK TRANSMISSION HARNESS. 
    1. Turn the ignition switch to OFF.
    2. Disconnect the transmission connector.
    3. Disconnect the front wheel speed sensor connector.
    4. Measure the resistance between transmission connector and front wheel speed sensor connector.

       Connector & terminal 

       (T4) No. 7 - (AT5) No. 1:

       (T4) No. 12 - (AT5) No. 2:

       (T4) No. 13 - (AT5) No. 3:

    Is the resistance less than 1 Ω?

    Yes: Go to  14.

    No: Replace the transmission harness.

14. CHECK FRONT WHEEL SPEED SENSOR HARNESS. 

    Measure the resistance between transmission connector and chassis ground.

    Connector & terminal 

    (T4) No. 7 - Chassis ground:

    (T4) No. 12 - Chassis ground:

    Is the resistance 1 MΩ or more?

    Yes: Go to  15.

    No: Repair the short circuit of harness.

15. CHECK FRONT WHEEL SPEED SENSOR. 
    1. Turn the ignition switch to OFF.
    2. Replace the front wheel speed sensor. Refer to CONTINUOUSLY VARIABLE TRANSMISSION(TR690)>FRONT WHEEL SPEED SENSOR .
    3. Perform the Clear Memory Mode. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>CLEAR MEMORY MODE .
    4. Read the DTC.

    Is DTC P0720 displayed?

    Yes: Go to  16.

    No: The original front wheel speed sensor is defective.

16. CHECK SELF SHUT RELAY. 
    1. Turn the ignition switch to OFF.
    2. Replace the self shut relay.
    3. Perform the Clear Memory Mode. Refer to CONTINUOUSLY VARIABLE TRANSMISSION (DIAGNOSTICS)>CLEAR MEMORY MODE .
    4. Read the DTC.

    Is DTC P0720 displayed?

    Yes: Replace the TCM. Refer to CONTINUOUSLY VARIABLE TRANSMISSION(TR690)>TRANSMISSION CONTROL MODULE (TCM) .

    No: The original self shut relay is defective.