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For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 Regal 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input

Object Number: 534303 Size: MF
Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The PCM provides a 5 volt reference to the sensor circuit. A high fluid temperature or a short to ground on the signal circuit results in low signal voltage. The TFT sensor operating range is -40 to +151°C (-40 to +304°F).

If the PCM detects a continuous short to ground in the TFT sensor signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.

Conditions for Running the DTC

The system voltage is 9-18 volts.

Conditions for Setting the DTC

The PCM detects a TFT sensor voltage of less than 0.2 volts for 10 seconds.

Action Taken When the DTC Sets
    • The PCM does not turn on the malfunction indicator lamp (MIL).
    • The PCM freezes shift adapts.
    • The PCM calculates a default TFT from the ECT sensor and the IAT sensor.
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
    • The PCM stores DTC P0712 in PCM history.

Conditions for Clearing the DTC
    • A scan tool can clear the DTC.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids
    • Inspect the connectors at the controller, the component and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. A value below 0.2 volts indicates the fault is present. A value above 0.2 volts indicates the fault is intermittent.

    2.

  2. A value greater than 4.9 volts indicates the fault is in the transmission side.

    3.

  3. For resistance at other temperatures, refer to Transmission Fluid Temperature (TFT) Sensor Specifications .

    4.

  4. A value less than 10 K ohms indicates a short to ground in the harness or sensor. A value greater than 10 K ohms indicates the condition is intermittent.

    5.

  5. A value less than 10 K ohms indicates a short together between the TFT signal circuit and the ground circuit.

DTC P0712 TFT Sensor Circuit Low

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain Diagnostic System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls

2

  1. Install a Scan Tool .
  2. Turn ON the ignition with the engine OFF.

    3. Important: Before clearing the DTCs, use theScan Tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

  3. Record the Failure Records.
  4. Clear the DTCs.
  5. Using the Scan Tool , observe the TFT sensor voltage.

Does the Scan Tool indicate that the TFT sensor voltage is less than specified?

0.2 V

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect the transmission 20-way connector (additional DTCs will set).
  3. Turn ON the ignition with the engine OFF.

Does the Scan Tool indicate that the TFT sensor voltage is greater than specified?

4.9 volts

Go to Step 5

Go to Step 4

4

Test the signal circuit (CKT 1227) of the TFT sensor for a short to ground between the PCM and the AT inline 20-way connector.

Refer to Circuit Testing and General Electrical Diagnosis in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 10

5

  1. Connect the J 44152 jumper harness to the transmission side of the 20-way connector.
  2. Using the J 35616 connector test adapter kit, connect the J 39200 digital multimeter (DMM) from terminal L to terminal M of the J 44152 .

    3. Refer to Automatic Transmission Inline Harness Connector End View .

  3. Measure the resistance.

Does the resistance measure within the range specified for the given transmission temperatures?

3,164-3,867 ohms @ 20°C (68°F)

225-285 ohms @ 88°C (190°F)

Go to Step 6

Go to Step 7

6

Test the signal circuit (CKT 1227) of the TFT sensor for a short to ground between the AT inline 20-way connector and the TFT sensor.

Is the resistance greater than the specified value?

10 K ohms

Go to Diagnostic Aids

Go to Step 9

7

  1. Disconnect the TFT sensor from the transmission wiring harness.
  2. Using the J 39200 DMM, measure the resistance between terminal L and terminal M of the J 44152 jumper harness.

Is the resistance greater than the specified value?

10 K ohms

Go to Step 8

Go to Step 9

8

Replace the TFT sensor.

Refer to Fluid Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 11

--

9

Replace the automatic transmission wiring harness.

Refer to Solenoids and Wiring Harness Replacement .

Did you complete the replacement?

--

Go to Step 11

--

10

Replace the PCM.

Refer to Powertrain Control Module Replacement/Programming in Engine Controls.

Did you complete the replacement?

--

Go to Step 11

--

11

Perform the following procedure In order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Turn ON the ignition with the engine OFF.
    • The TFT signal voltage must be greater than 0.2 volts for 10 seconds.
  4. Select specific DTC.
  5. Enter DTC P0712.

Has the test run and passed?

--

System OK

Go to Step 1