P0712

DTC P0712





Circuit Description with 4L60-E / 4L65-E Automatic Transmission
The automatic Transmission Fluid Temperature (TFT) sensor is part of the automatic Transmission Fluid Pressure (TFP) manual valve position switch. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases, the resistance increases. The Powertrain Control Module (PCM) supplies a 5-volt reference signal to the sensor on the TFT sensor signal circuit and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.

When the PCM detects a continuous short to ground in the TFT signal circuit or in the TFT sensor, then DTC P0712 sets. DTC P0712 is a type C DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Voltage

Conditions for Running the DTC
^ The system voltage is 10 - 18 volts.
^ The ignition is ON.

Conditions for Setting the DTC
The TFT sensor indicates a signal voltage less than 0.25 volts for 10 seconds.

Action Taken When the DTC Sets
^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

^ Important: The actions listed below are in order of highest to lowest priority.
The PCM determines a default TFT using one of the following:
^ If any ECT DTC's P0117 or P0118 are set, then the default TFT is equal to 135°C (275°F).
^ If the ECT is 125°C (257°F) or more, then the default TFT is equal to 135°C (275°F).
^ If the engine run time is less than 300 seconds and:

^ No Intake Air Temperature (IAT) DTC's P0112 or P0113 are set and IAT is available, then the default TFT is equal to IAT.
^ Any IAT DTC's P0112 or P0113 are set or IAT is NOT available, then the default TFT is equal to 90°C (194°F).
^ If the engine run time is greater than 300 seconds and no IAT DTC's P0112 or P0113 are set and IAT is available and ECT is between 40 and 125°C (104 and 257°F) and:
^ IAT at start-up is less than 15°C (59°F), then the default TFT is equal to the ECT plus 5°C (8°F).
^ IAT at start-up is greater than 35°C (95°F), then the default TFT is equal to the ECT plus 10°C (16°F).
^ IAT at start-up is between 15 and 35°C (59 and 95°F), then the default TFT is equal to the ECT.
^ If the engine run time is greater than 300 seconds and any IAT DTC's P0112 or P0113 are set or IAT is NOT available, then the default TFT is equal to the ECT.
^ If the engine run time is greater than 300 seconds and ECT is less than 40°C (104°F) or more, then the default TFT is equal to 60°C (140°F).
^ The PCM freezes Transmission Adaptive Functions from being updated.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
^ The PCM stores DTC P0712 in PCM history.

Conditions for Clearing the DTC
^ A scan tool can clear the DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
^ The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids
^ The scan tool displays the transmission fluid temperature in degrees. After the transmission is operating, the fluid temperature should rise steadily to a normal operating temperature, then stabilize.
^ Verify the customer's driving habits, trailer towing, etc. Trailer towing should occur in D3.

Test Description








The numbers below refer to the step numbers on the diagnostic table.
3. This step tests for a short to ground condition.
4. This step tests for an internal fault within the transmission by creating an open.