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Home >> Subaru >> 2013 >> Legacy Premium, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 16 (Automatic Transaxle - Diagnostics) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0712 Transmission Fluid Temperature Sensor Circuit Low Input >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN TCM AND ATF TEMPERATURE SENSOR. 
  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 

    (B55) No. 12 - (B11) No. 15: 

    (B55) No. 23 - (B11) No. 11: 

 Is the resistance less than 1 Ω? Go to step 2  . Repair the open circuit of harness between TCM and transmission connector.
2 CHECK ATF TEMPERATURE SENSOR. 
  1. Turn the ignition switch to OFF.
  2. Connect the connectors to TCM and transmission.
  3. Start the engine.
  4. Warm up the transmission until the ATF temperature exceeds 80°C (176°F).
  5. Disconnect the connector from transmission.
  6. Measure the resistance between transmission connector terminals.

    Connector & terminal 

    (T4) No. 11 - No. 15: 

 Is the resistance 300 - 800 Ω? Go to step 3  . Go to step 5  .
3 CHECK ATF TEMPERATURE SENSOR. 
Measure the resistance between transmission connector terminals.
Connector & terminal 
(T4) No. 11 - No. 15: 		 Does the resistance value increase gradually while the ATF temperature decreases? Go to step 4  . Go to step 5  .
4 CHECK INPUT SIGNAL FOR TCM. 
  1. Connect the connector to transmission.
  2. Connect the Subaru Select Monitor to data link connector.
  3. Turn the ignition switch to ON.
  4. Read the data of «ATF Temp.» using the Subaru Select Monitor.
 Does the ATF temperature gradually decrease? Check for poor contact of the ATF temperature sensor and transmission connector harness, and repair the defective part. Go to step 6  .
5 CHECK HARNESS CONNECTOR BETWEEN TRANSMISSION AND ATF TEMPERATURE SENSOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from transmission.
  3. Remove the transmission connector from bracket.
  4. Lift up the vehicle.
  5. Drain the automatic transmission fluid.
    CAUTION: Do not drain ATF until it cools down.
  6. Remove the oil pan.
  7. Disconnect the connector from the control valve body.
  8. Measure the resistance of harness between ATF temperature sensor and transmission connector.

    Connector & terminal 

    (T4) No. 11 - (AT2) No. 4: 

    (T4) No. 15 - (AT2) No. 9: 

 Is the resistance less than 1 Ω? Replace the control valve body. < Refer to CONTROL VALVE BODY . > Repair the open circuit of harness between ATF temperature sensor and transmission connector.
6 CHECK FOR POOR CONTACT.  Is there poor contact of ATF temperature sensor circuit? Repair the poor contact. Replace the TCM. < Refer to TRANSMISSION CONTROL MODULE (TCM) . >
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