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).

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.

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.