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Home >> Ford >> 2006 >> Freestar Base >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission >> Diagnosis And Testing >> Pinpoint Tests - Non OSC Equipped Vehicle >> Pinpoint Tests >> Pinpoint Test B: Transmission Fluid Temperature (TFT) Sensor

Pinpoint Test B: Transmission Fluid Temperature (TFT) Sensor

NOTE: Refer to the Transaxle Vehicle Harness Connector (Figure) illustration preceding these pinpoint tests.
NOTE: Refer to the Transaxle Internal Harness Diagram (Figure) illustration preceding these pinpoint tests.
  1. B1 ELECTRONIC DIAGNOSTICS 
    • Check to make sure the transaxle harness connector is fully seated, terminals are fully engaged in connector and in good condition before proceeding.
    • Have the above items been checked? 

    Yes  : GO to  B2.

    No  : CARRY OUT checks. ERASE the codes. REPEAT the Quick Test.

  2. B2 CHECK THE ELECTRICAL SIGNAL OPERATION 
    • Key in OFF position.
    • Disconnect: Transaxle Vehicle Harness Connector.
      CAUTION: Do not pry on the connector. This will damage the connector and could result in a transaxle concern. Pull up on the connector harness.

      Disconnect the transaxle vehicle connector.

    • Use a mirror to inspect both ends of the connector for damage or pushed out pins, corrosion, loose wires and missing or damaged seals.
    • Connect a VOM positive lead to the transmission fluid temperature (TFT) circuit pin 5 and the negative test lead to the signal return (SIG RTN) pin 9 of the transaxle vehicle harness connector.
      Fig 1: Checking Electrical Signal Operation
      G04660966Courtesy of FORD MOTOR CO.
    • Place the VOM on the 20 volt scale.
    • Key in ON position.
    • Is the voltage between 4.75 and 5.25 volts? 

    Yes  : GO to  B7.

    No  : GO to  B3.

  3. B3 CHECK THE CONTINUITY OF THE TFT AND SIG RTN CIRCUITS 
    • Key in OFF position.
    • Disconnect: Transaxle Vehicle Harness Connector.
    • Disconnect: Powertrain Control Module (PCM).
    • Inspect for damaged or pushed out pins, corrosion or loose wires.
    • Install the EEC-V Control System Breakout Box.
    • Measure the resistance between PCM signal test pin 37 at the EEC-V Control System Breakout Box and signal test pin 5 at the transaxle vehicle harness connector.
      Fig 2: Checking Continuity Of TFT And SIG RTN Circuits (1 Of 2)
      G04660967Courtesy of FORD MOTOR CO.
    • Measure the resistance between PCM signal test pin 91 at the EEC-V Control System Breakout Box and signal test pin 9 at the transaxle vehicle harness connector.
      Fig 3: Checking Continuity Of TFT And SIG RTN Circuits (2 Of 2)
      G04660968Courtesy of FORD MOTOR CO.
    • Is each resistance less than 5 ohms? 

    Yes  : GO to  B4.

    No  : REPAIR the open circuits. REMOVE the EEC-V Control System Breakout Box. RECONNECT all of the components. REPEAT the Quick Tests.

  4. B4 CHECK THE TFT CIRCUIT FOR A SHORT TO VPWR AND GROUND 
    • Inspect for damaged or pushed out pins, corrosion or loose wires.
    • Measure the resistance between TFT test pin 37 and test pin 71 at the EEC-V Control System Breakout Box.
      Fig 4: Checking TFT Circuit For Short To VPWR And Ground (1 Of 2)
      G04660969Courtesy of FORD MOTOR CO.
    • Measure the resistance between TFT test pin 37 and chassis ground, pins 24, 25, 51, 76, 77, 91, and 103.
      Fig 5: Checking TFT Circuit For Short To VPWR And Ground (2 Of 2)
      G04660970Courtesy of FORD MOTOR CO.
    • Is each resistance greater than 10,000 ohms? 

    Yes  : GO to  B5.

    No  : REPAIR the short circuit(s). REMOVE the EEC-V Control System Breakout Box. RECONNECT all of the components. REPEAT the Quick Tests.

  5. B5 CHECK THE RESISTANCE OF THE TFT SENSORS/HARNESS 
    • Vehicle must be at normal operating temperature.
    • Disconnect: Transaxle Vehicle Harness Connector.
      CAUTION: Do not pry on the connector. This will damage the connector and could result in a transaxle concern. Pull up on the connector harness.

      Disconnect the transaxle vehicle harness connector.

    • Connect the transmission tester.
    • Set the Bench/Drive switch to BENCH mode.
    • Rotate the Gear Select switch to OHMS CHECK position.
      • NOTE: While carrying out test 1 and 2, observe the resistance. DTC P0713 is set if resistance value exceeds 869 K ohms (open circuit). DTC P0712 is set if resistance value falls below 597 ohms (short circuit).
      Fig 6: Checking Resistance Of TFT Sensors/Harness
      G04660971Courtesy of FORD MOTOR CO.
    • Connect the ohmmeter negative lead to the -TFT jack and the positive lead to the +TFT jack on the tester.
    • TEST 1. 
    • Record the resistance.
    • Resistance should be approximately in the following ranges:
      TRANSMISSION FLUID TEMPERATURE

      °C °F Resistance (Ohms)
      -40 to -20 -40 to -4 967 K-284 K
      -19 to -1 -3 to 31 284 K-100 K
      0-20 32-68 100 K-37 K
      21-40 69-104 37 K-16 K
      41-70 105-158 16 K-5 K
      71-90 159-194 5 K-2.7 K
      91-110 195-230 2.7 K-1.5 K
      111-130 231-266 1.5 K-0.8 K
      131-150 267-302 0.8 K-0.54 K
    • TEST 2. 
    • Check for intermittent short or open.
    • If the resistance was between 0.8 K and 100 K ohms carry out the following test. If the transaxle is warm, allow it to cool. Check the transmission fluid temperature sensor resistance again. Compare the resistance with the initial resistance. The resistance should decrease if the transaxle was heated and should increase if the transaxle was allowed to cool. If correct, then change in the resistance occurs, repeat On-Board Diagnostic.
    • Is the resistance in the range? 

    Yes  : GO to  B6.

    No  : GO to  B7.

  6. B6 CHECK THE SENSOR/HARNESS FOR A SHORT TO GROUND 
    • Check for continuity between the BAT(-) jack (engine ground) and the appropriate jack (-TFT or +TFT) with an ohmmeter or other low current tester (less than 200 milliamps).
      Fig 7: Checking Sensor/Harness For Short To Ground
      G04660972Courtesy of FORD MOTOR CO.
    • Connection should show infinite resistance (no continuity).
    • Does the connection show continuity? 

    Yes  : GO to  B7.

    No  : INSTALL a new PCM. REPEAT the On-Board Diagnostics; if the DTC is still present, GO to  B7.

  7. B7 INTERNAL ELECTRONIC DIAGNOSTICS 
    • Remove the transaxle side pan.
    • Check that the internal harness connector is fully engaged on the TFT sensor.
    • Check that the internal harness connector terminals are fully seated in the connector.
    • Inspect the connector for damage.
    • Are the above in good condition? 

    Yes  : GO to  B8.

    No  : REPAIR as required.

  8. B8 CHECK THE INTERNAL HARNESS (CONTINUITY) 
    • Disconnect: Internal Harness From TFT Sensor.
      CAUTION: Do not probe into the connector terminals. This will damage the connector and could result in a transaxle concern.

      For the TFT sensor, connect the positive lead from an ohmmeter to the tester +TFT jack and the negative lead at the black wire of the TFT sensor connector.

      Fig 8: Checking Internal Harness (Continuity) (1 Of 2)
      G04660973Courtesy of FORD MOTOR CO.
    • Record the resistance. The resistance should be less than 0.5 ohms.
    • Connect the positive lead from an ohmmeter to the tester -TFT jack and the negative lead at the white wire of the TFT sensor connector.
      Fig 9: Checking Internal Harness (Continuity) (2 Of 2)
      G04660974Courtesy of FORD MOTOR CO.
    • Record the resistance. The resistance should be less than 0.5 ohms.
    • Is the resistance less than 0.5 ohms? 

    Yes  : GO to  B9.

    No  : INSTALL a new internal harness. GO to  B10.

  9. B9 CHECK THE INTERNAL HARNESS (SHORT TO GROUND) 
    • Check for continuity between BAT(-) jack (engine ground) and the appropriate wire (+TFT and -TFT) with an ohmmeter or other low current tester (less than 200 milliamps).
      INTERNAL SENSOR SPECIFICATION

      Sensor Wire
      TFT+ Black
      TFT- White
      Fig 10: Checking Internal Harness (Short To Ground)
      G04660975Courtesy of FORD MOTOR CO.
    • Connection should show infinite resistance (no continuity).
    • Does the connection show continuity? 

    Yes  : INSTALL a new internal harness. GO to  B10.

    No  : GO to  B10.

  10. B10 CHECK THE TFT SENSOR RESISTANCE 
    • Check the sensor resistance by connecting an ohmmeter at the terminals of the TFT sensor assembly.
      Fig 11: Checking TFT Sensor Resistance
      G04660976Courtesy of FORD MOTOR CO.
    • Record the resistance.
    • The resistance should be in range of the temperature of the vehicle.
    • The resistance should be approximately in the following ranges:
      TRANSMISSION FLUID TEMPERATURE

      °C °F Resistance (Ohms)
      -40 to -20 -40 to -4 967 K-284 K
      -19 to -1 -3 to 31 284 K-100 K
      0-20 32-68 100 K-37 K
      21-40 69-10 437 K-16 K
      41-70 105-158 16 K-5 K
      71-90 159-194 5 K-2.7 K
      91-110 195-230 2.7 K-1.5 K
      111-130 231-266 1.5 K-0.8 K
      131-150 267-302 0.8 K-0.54 K
    • Is the resistance in the range? 

    Yes  : GO to  B11.

    No  : INSTALL a new TFT sensor.

  11. B11 CHECK THE TFT SENSOR FOR SHORT TO GROUND 
    • Check for continuity between BAT(-) jack (engine ground) and the appropriate terminal with an ohmmeter or other low current tester (less than 200 milliamps).
      TFT SENSOR REFERENCE

      Sensor Wire
      TFT +/-
      Fig 12: Checking TFT Sensor For Short To Ground
      G04660977Courtesy of FORD MOTOR CO.
    • Connection should show infinite resistance (no continuity).
    • Does the connection show continuity? 

    Yes  : INSTALL a new TFT sensor.

    No  : REPEAT the Quick Test. If codes are present and an over temperature condition existed, CHECK the fluid condition. CHECK the overheat condition. REFER to DIAGNOSIS BY SYMPTOM  in this article. REPAIR as required. REPEAT the Quick Test.

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