DTC P1706: Rear Output Shaft Speed Sensor Circuit No Signal: Notes

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

1. -

DTC detecting condition:

Immediately at fault recognition

Trouble symptom:

AWD does not function.

Wiring diagram:

CVT control system Ref. to WIRING SYSTEM>CVT CONTROL SYSTEM>WIRING DIAGRAM

DC power supply circuit Ref. to WIRING SYSTEM>POWER SUPPLY CIRCUIT>WIRING DIAGRAM

Engine electrical system Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

Use the check board when measuring the TCM/ECM terminal voltage and resistance.
After servicing or replacing faulty parts, perform the last step of the basic diagnostic procedure. Ref. to TRANSMISSION (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE

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

Is DTC P0890 displayed?

Yes : Perform the diagnosis according to DTC P0890. Ref. to TRANSMISSION (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0890 TCM POWER RELAY SENSE CIRCUIT LOW

No : Go to 2.
CHECK THE CONNECTORS INDICATED IN THE WIRING DIAGRAM .
Check connecting condition of the connectors indicated in the wiring diagram.

Are the connectors indicated in the wiring diagram properly connected?

Yes : Go to 3.

No : Properly connect the connectors indicated in the wiring diagram.
CHECK HARNESS BETWEEN TRANSMISSION CONNECTOR AND MAIN RELAY CONNECTOR .
1. Turn the ignition switch to OFF.
2. Measure the voltage between transmission connector and chassis ground.
  Connector & terminal
  
  (T1) No. 2 (+) - Chassis ground (-):
Is the voltage 10 V or more?

Yes : Repair the harness and connector.
NOTE:
In this case, repair the following item:
- Short circuit to power supply of harness between transmission connector and main relay connector
- Defective main relay
No : Go to 4.
CHECK HARNESS BETWEEN ECM AND MAIN RELAY CONNECTOR .
1. Turn the ignition switch to OFF.
2. Remove the main relay.
3. Disconnect the ECM connector.
4. Measure the resistance between the ECM connector and engine ground.
  Connector & terminal
  
  (B61) No. 29 - Engine ground:
Is the resistance 1 MΩ or more?

Yes : Go to 5.

No : Repair the short circuit to ground in harness between ECM connector and main relay connector.
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
  
  (B67) No. 11 - (E34) No. 17:
  
  (B67) No. 26 - (E34) No. 19:
Is the resistance less than 1 Ω?

Yes : Go to 6.

No : Repair the open circuit of harness.
CHECK HARNESS .
Measure the resistance between TCM connector and chassis ground.

Connector & terminal

(B67) No. 11 - Chassis ground:

Is the resistance 1 MΩ or more?

Yes : Go to 7.

No : Repair the short circuit of harness.
CHECK TRANSMISSION HARNESS .
1. Install the fuse.
2. Connect the TCM connector.
3. Disconnect the transmission connector. (E34, T1)
4. Turn the ignition switch to ON.
5. Measure the voltage between transmission connector and chassis ground.
  Connector & terminal
  
  (E34) No. 2 (+) - Chassis ground (-):
Is the voltage 10 - 13 V?

Yes : Go to 8.

No : Repair the open circuit of harness or poor contact of connector.
CHECK INPUT SIGNAL FOR TCM .
1. Turn the ignition switch to OFF.
2. Connect all connectors.
3. Lift up the vehicle.
4. Start the engine.
5. Drive in "D" range.
6. Using the Subaru Select Monitor, read data of [Rear Wheel Speed] in the [Data Monitor] of [Transmission]. Ref. to TRANSMISSION (DIAGNOSTICS)>DATA MONITOR
Does the value of [Rear Wheel Speed] change according to the engine speed?

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

No : Go to 9.
CHECK TRANSMISSION HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the transmission connector.
3. Disconnect the rear wheel speed sensor connector.
4. Measure the resistance between transmission connector and rear wheel speed sensor connector.
  Connector & terminal
  
  (T1) No. 2 - (T42) No. 3:
  
  (T1) No. 17 - (T42) No. 2:
  
  (T1) No. 19 - (T42) No. 1:
Is the resistance less than 1 Ω?

Yes : Go to 10.

No : Replace the transmission harness. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION HARNESS
CHECK REAR WHEEL SPEED SENSOR HARNESS .
Measure the resistance between transmission connector and chassis ground.

Connector & terminal

(T1) No. 2 - Chassis ground:

(T1) No. 17 - Chassis ground:

Is the resistance 1 MΩ or more?

Yes : Replace the rear wheel speed sensor. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>REAR WHEEL SPEED SENSOR

No : Repair the short circuit of harness.