P0712

Diagnostic Chart:

Circuit Description

The Automatic Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor. The sensor resistance changes with temperature. The Powertrain Control Module (PCM) provides a 5-volt reference to the sensor on circuit 1227. A short to ground in circuit 1227 results in low signal voltage. The TFT operating range is from -40 to +140°C (-40 to +284°F).

When the PCM detects a voltage input of less than 0.20 V in the TFT Sensor circuit, then DTC P0712 sets. DTC P0712 is a type D DTC.

Conditions for Setting the DTC

^ No System Voltage Malfunction DTC P0560 is set.

^ The ignition is ON.

^ The PCM detects a TFT sensor voltage of 0.20 volts or less for 10 seconds.

Action Taken When the DTC Sets

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

- The Intake Air Temperature (IAT) DTC(s) P0112, P0113, P1111, or P1112 is set, then the default Automatic Transmission Fluid Temperature (TFT) is set to 0°C (32°F).

- No IAT DTC is set, then the TFT is set to the IAT value which was saved at start up.

^ If the engine run time is greater than 3 minutes and:

- The Engine Coolant Temperature (ECT) DTC(s) P0117, P0118, 1114, or P1115 is set. then the default DTC is set to 131°C (268°F).

- No ECT DTC is set and:

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

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

- No ECT DTC is set. the ECT is 45-115°C (113-239°F) and:

^ The IAT DTC(s) 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 the ECT value minus 10°C (18°F).

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

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

^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

Conditions for Clearing the MIL/DTC

^ The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported.

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history it 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 at the transmission 7-way connector. Look for the following conditions:

- A bent terminal

- A backed out terminal

- A damaged terminal

- Poor terminal tension

- A chafed wire

- A broken wire inside the insulation

^ When diagnosing for an intermittent short or open condition. massage the wiring harness while watching the test equipment for a change.

^ inspect the transmission harness for a short to ground. Inspect the engine harness for a short to ground.

^ Inspect the transmission cooling system for blockage or other restrictions

^ Refer to Temperature vs Resistance. Specifications

Test Description

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

3. A scan tool display of 145°C (293°F) or more indicates that this DTC is current.

4. This action isolates the fault between the transmission harness and the engine harness.