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 1227/452. A high fluid temperature or a short to ground on circuit 1227/452 results in low signal voltage. The TFT operating range is -40 to +151°C (-40 to +305°F).

If 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 Running the DTC

^ The ignition switch is in the RUN position.
^ The system voltage is 10-17 volts.

Conditions for Setting the DTC

The PCM detects a TFT of 148°C (298°F) or greater (0.08 volts or less) for 5 seconds.

Action Taken When the DTC Sets

^ The PCM does not illuminate the malfunction indicator lamp (MIL).
^ The PCM calculates a default transmission fluid temperature based on engine coolant temperature, intake air temperature and engine run time.
^ The PCM stores DTC P0712 in PCM history.

Conditions for Clearing the DTC

^ A scan tool clears the DTC from PCM history.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a nonemission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch 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 the TFT sensor 2-way connector for the following conditions:
- A backed out terminal
- A damaged terminal
- Reduced terminal tension
- A chafed wire
- A broken wire inside the insulation
- Moisture intrusion
^ 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.

2. This step ensures that the transmission fluid is at the proper level.
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 0.08 volts, then the DTC is intermittent.
4. This step isolates the transmission. If the scan tool displays a voltage greater than 4.8 volts, then the engine wiring harness is good.
6. This step tests the TFT sensor for correct resistance.