P0712

Diagnostic Chart:

CIRCUIT DESCRIPTION

The Automatic Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The Powertrain Control Module (PCM) provides a 5 volt reference to the sensor on circuit 585/1227. A high fluid temperature or a short to ground on circuit 585/1227 results in low signal voltage. The TFT operating range is -40 to +151°C (-40 to +305°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 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).

^ If any engine coolant temperature sensor codes set, the PCM substitutes a transmission fluid temperature default value of 132°C (269°F).

^ If the engine coolant temperature is greater than 115°C (239°F), the PCM substitutes a transmission fluid temperature default value of 132°C (269°F). This enables transmission Hot Mode. The transmission remains in Hot Mode until the engine coolant temperature drops below 110°C (230°F).

^ If the engine run time is less than 3 minutes, the PCM substitutes the intake air temperature for the transmission fluid temperature value at ignition ON.

^ If the engine coolant temperature is 45-115°C (113-239°F), the transmission fluid default temperature equals ECT-10°C when the intake air temperature is less than 27°C (81°F) at ignition ON. If the intake air temperature is greater than 27°C (81°F) at ignition ON, the transmission fluid default temperature equals ECT+10°C.

^ If the engine run time is greater than 3 minutes and the engine coolant temperature is less than 45°C (113°F), the PCM substitutes a transmission fluid temperature default value of 12°C (54°F).

^ DTC P0712 is stored in the PCM history.

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, the transmission 20-way connector, the TFT sensor 2-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 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 circuit 1227 inside of the transmission for a short to ground.