P0712

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).
If the PCM detects a continuous short to ground in TFT sensor circuit 1227, then DTC P0712 sets. DTC P0712 is a type D DTC.

Conditions for Setting the DTC
^ The system voltage is 9-16 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.
^ The default TFT will be determined through the following calculations:
- If the Engine Run Time is less than 3 minutes and:
^ Intake Air Temperature (IAT) DTC P0112, P0113, Pull 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 (288°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 at the PCM, the transmission 20-way connector and all other circuit connecting points 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
- Moisture intrusion
- Corrosion
^ 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 the TFT sensor at various temperature levels to evaluate the possibility of a skewed (mis-scaled) sensor. Refer to Specifications / Temperature vs Resistance Table.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. 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.
4. This step isolates the transmission. If the scan tool displays a voltage greater than 4.920 volts, then the engine wiring harness is good.