DTC P0712: Transmission Fluid Temperature Sensor "A" Circuit Low: 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:

Excessive shift shock
Shift characteristics malfunction

Wiring diagram:

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

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

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)>BASIC DIAGNOSTIC PROCEDURE

CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the TCM connector.
3. Measure the resistance of harness between TCM connector and chassis ground.
  Connector & terminal
  
  (B67) No. 1 - Chassis ground:
  
  (B67) No. 6 - Chassis ground:
Is the resistance 1 MΩ or more?

Yes : Go to 4.

No : Go to 2.
CHECK HARNESS .
1. Disconnect the transmission connector.
2. Measure the resistance of harness between transmission connector and transmission body.
  Connector & terminal
  
  (T1) No. 4 - Chassis ground:
  
  (T1) No. 16 - Chassis ground:
Is the resistance 1 MΩ or more?

Yes : Repair the short circuit of body harness.

No : Go to 3.
CHECK HARNESS INSIDE TRANSMISSION .
CAUTION:
Start work after ATF cools down.
1. Remove the transmission oil pan.
2. Check for the harness pinch, damage.
Is the check result OK?

Yes : Go to 4.

No : Replace the transmission harness. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>TRANSMISSION HARNESS
CHECK ATF TEMPERATURE SENSOR .
Measure the resistance between transmission connector terminals.

Connector & terminal

(T1) No. 4 - (T1) No. 16:

NOTE:
Perform the measurements using multiple oil temperatures.

Is resistance as follows?

Fluid temperature 0°C → Approx. 6.2 kΩ

Fluid temperature 20°C → Approx. 2.6 kΩ

Fluid temperature 80°C → Approx. 370 Ω

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

No : Replace the control valve body. Ref. to CONTINUOUSLY VARIABLE TRANSMISSION (TR690)>CONTROL VALVE BODY