P0713

CIRCUIT DESCRIPTION
The Automatic Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor. When the transmission fluid is cold, the sensor resistance is high. As the transmission fluid warms, the sensor resistance decreases. The TFT range is -40 to +150°C (-40 to +302°F).

The PCM provides a 5 volt reference through a fixed series resistor, to the TFT circuit and monitors the voltage after the resistor, as the voltage drop (signal) across the circuit.

When the PCM detects a voltage input greater than 4.92 volts in the TFT Sensor circuit, indicating an open or short to power, then DTC P0713 sets. DTC P0713 is a type D DTC.

CONDITIONS FOR SETTING THE DTC
- System voltage is 10-16 volts.
- The ignition is ON.
- The PCM detects a transmission fluid temperature of -35°C (-31°F) or less (4.92 volts or more) for 7 minutes.

ACTION TAKEN WHEN THE DTC SETS
- The PCM does not illuminate the Malfunction Indicator Lamp (MIL).
- The PCM calculates a transmission fluid default temperature as follows:
- 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 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(s) P0117, P0118, P1114 or P1115 is set, then the default TFT 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.

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 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 or open, massage the wiring harness while watching the test equipment for a change.
- Test the TFT Sensor at various temperature levels in order to evaluate the possibility of a skewed (mis-scaled) sensor.
Refer to Temperature vs Resistance.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
3. A scan tool Transmission Fluid Temperature of -36°C (-33°F) or less indicates this DTC is current.
4. This step isolates the fault between the transmission harness or the engine harness.