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Diagnostic Chart:

Wiring Diagram:

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 +151°C (-40 to +304°F).

If the PCM detects a voltage input of less than 200 mV 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 0.20 volts or less for 10 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM does not turn on the Malfunction Indicator Lamp (MIL).
^ 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 Automatic Transmission Fluid Temperature (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 an 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 at the transmission 7-way connector. Look for the following problems:

- 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, massage the wiring hamess 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 chart.

3. A scan tool display of 145°C (293°F) or more indicates that this DTC is current.
4. This Step isolates the fault between the transmission harness and the engine hamess.