For 1990-2009 cars
Automatic Transmission Components VIN 1 and K
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 on circuit 1227. A high fluid temperature or a short to ground on circuit 1227 results in low signal voltage. The TFT operating range is -40 to +151°C (-40 to +304°F).

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

### Conditions for Setting the DTC

• | The system voltage is 10-16 volts.

• | The ignition is ON.

• | The PCM detects a TFT sensor voltage of 0.200 volts or less for 10 seconds.

### Action Taken When the DTC Sets

• | The PCM does not turn on the Malfunction Indicator Lamp (MIL).

• | The PCM disables shift adapts.

• | If the Engine Run Time is less than 3 minutes and:

• | Intake Air Temperature (IAT) DTC P0112, P0113, P1111, or P1112 is set, then the default TFT is 0°C (32°F).

• | No IAT DTC is set, then the default TFT is set to the IAT saved at start up.

• | If the engine run time is greater than 3 minutes, and the Engine Coolant Temperature (ECT) DTC P0117, P0118, P1114, or P1115 is set, then the default TFT is 131°C (268°F).

• | If the engine run time is greater than 3 minutes, no ECT DTC is set, and:

• | The ECT is less than 45°C (113°F), then the default TFT is 12°C (54°F).

• | The ECT is greater than 115°C (239°F), then the default TFT is 131°C (268°F).

• | The ECT is 45-115°C (113-239°F) and:

- | The IAT DTC P0112, P0113, P1111, or P1112 is set, then the default TFT is set to equal the ECT.

- | The IAT at start up is less than 0°C (32°F), then the default TFT is set to ECT minus 10°C (18°F).

- | The IAT at start up is greater than 28°C (82°F), then the default TFT is set to ECT plus 10°C (18°F).

- | The IAT at start up is 0-28°C (32-82°F), then the default TFT is set to equal ECT.

### Conditions for Clearing the DTC

• | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

• | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

### Diagnostic Aids

• | Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Inspect the wiring for poor electrical connections at the Automatic Transmission Fluid Temperature sensor connector. Look for the following conditions:

- | A bent terminal

- | A backed out terminal

- | A damaged terminal

- | Poor terminal tension

- | A chafed wire

• | When diagnosing for an intermittent short to ground or short to power, massage the wiring harness while watching the test equipment for a change.

### Test Description

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

1. This step verifies DTC P0712 by indicating a short to ground. If the scan tool does not display a voltage value equal to or less than 0.200 volts, then the DTC is intermittent.

2. This step isolates the transmission. If the scan tool displays a voltage greater than 4.920 volts, then the engine wiring harness is good.

#### DTC P0712 Automatic Transmission Fluid Temperature sensor Circuit Low Input

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Has the transmission fluid checking procedure been performed? | -- | Go to Step 3 | Go to Transmission Fluid Check
3 |

1. Install the Scan Tool ®.
2. With the engine OFF, turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data.

3. Record the DTC Failure Records.
4. Select TFT sensor volts on the scan tool.

Does the scan tool display a TFT sensor voltage less than the specified value?

0.200 volts

Go to Step 4

Go to Diagnostic Aids

4 |

1. Turn the ignition OFF.
2. Disconnect the transmission 20-way connector.

Does the scan tool display an Automatic Transmission Fluid Temperature voltage greater than the specified value?

4.920 volts

Go to Step 6

Go to Step 5

5 | Inspect circuit 1227 of the engine wiring harness for a short to ground. Refer to Electrical Diagnosis, Section 8. Did you find and correct the problem? | -- | Go to Step 10 | Go to Step 9
6 |

1. Connect the J 39775 Jumper Harness to the transmission 20-way connector. (Connector End View )
2. Connect an ohmmeter from terminal M to the transmission case.

Does the ohmmeter display a resistance greater than the specified value?

100ohms

Go to Step 9

Go to Step 7

7 | Inspect circuit 1227 for a short to ground. Refer to Electrical Diagnosis, Section 8. Did you find and correct the problem? | -- | Go to Step 10 | Go to Step 8
8 | Replace the TFT Sensor. Refer to Solenoids and Wiring Harness, in On-Vehicle Service. Is the replacement complete? | -- | Go to Step 10 | --
9 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | Go to Step 10 | --
10 | In order to verify your repair, perform the following procedure:

1. Select DTC.
2. Select Clear Info.
3. Operate the vehicle so that the TFT Sensor voltage is greater than 0.200 volts for more than 10 seconds.
4. Select Specific DTC. Enter DTC P0712.

Has the test run and passed?

--

System OK

Begin the diagnosis again. Go to Step 1