DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Input 3.8L


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Circuit Description

The automatic transmission fluid temperature (TFT) sensor is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases, the resistance increases. The powertrain control module (PCM) supplies a 5-volt reference signal to the sensor on circuit 1227 and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.

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

Conditions for Running the DTC

Conditions for Setting the DTC

The TFT sensor indicates a signal voltage less than 0.2 volts for 10 seconds.

Action Taken When the DTC Sets

The scan tool does not indicate the default TFT.

Important

The actions listed below are in order of highest to lowest priority.

The PCM determines a default TFT using one of the following:

Conditions for Clearing the DTC

Diagnostic Aids

Test Description

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

  1. This step tests for a short to ground condition.
  1. This step tests for an internal fault in the transmission by creating an open.

DTC P0712 TFT Sensor Circuit Low Input (3.8L)

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain Diagnostic System Check?

--

Go to Step 2

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

2

Inspect for correct transmission fluid level. Refer to Transmission Fluid Checking Procedure . Did you perform the fluid checking procedure?

--

Go to Step 3

Go to Transmission Fluid Checking Procedure

3

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

Important

Before clearing the DTC, use the Scan Tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

  1. Record the DTC Failure Records.
  2. Clear the DTC.

Does the Scan Tool display a TFT Sensor signal voltage greater than the specified value?

0.2 V

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the AT inline 20-way connector (additional DTCs may set).
  3. Turn ON the ignition, with the engine OFF.

Does the Scan Tool display a TFT Sensor signal voltage greater than the specified value?

4.92 V

Go to Step 5

Go to Step 7

5

  1. Install the J 44152 jumper harness (20 pins) on the transmission side of the AT inline 20-way connector.
  2. Using the J 39200 digital multimeter (DMM) and the J 35616-A connector test adapter kit, measure the resistance between terminals L and M of the J 44152 . Refer to Automatic Transmission Inline Harness Connector End View .

Does the resistance measure within the specified range?

3088-3942 ohms at 20C (68F) 159-198 ohms at 100C (212F)

Go to Diagnostic Aids

Go to Step 6

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. Refer to Circuit Testing in Wiring Systems. Did you find a short to ground condition?

--

Go to Step 9

Go to Step 8

7

Test the signal circuit (CKT 1227) of the TFT sensor for a short to ground between the PCM connector C2 and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?

--

Go to Step 11

Go to Step 10

8

Replace the TFT sensor (this sensor is part of the TFP manual valve position switch). Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement?

--

Go to Step 11

--

9

Replace the AT wiring harness assembly. Refer to Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid, TCC Solenoid, and Wiring Harness . Did you complete the replacement?

--

Go to Step 11

--

10

Replace the PCM. Refer to PCM 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. Turn ON the ignition, with the engine OFF.
  4. Verify that the Scan Tool indicates a TFT Sensor signal voltage greater than 0.2 volts for 10 seconds.
  5. Select Specific DTC.
  6. Enter DTC P0712.

Has the test run and passed?

--

System OK

Go to Step 1