Diagnostic Instructions

DTC Descriptors

DTC P0712:  Transmission Fluid Temperature (TFT) Sensor Circuit Low Voltage

DTC P0713:  Transmission Fluid Temperature (TFT) Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
TFT Sensor Signal	P0712	P0713	P0713	P0218, P0711
Low Reference	--	P0713	--	P0218, P0711

Typical Scan Tool Data

Transmission Fluid Temperature

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
Operating Conditions: Engine running in PARK, normal operating temperature Parameter Normal Range: -40 to +149°C (-40 to +300°F)
Trans. Fluid Temp.	Greater than 149°C (300°F)	Less than -40°C (-40°F)	Less than -40°C (-40°F)

Circuit/System Description

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor. The TFT sensor is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The transmission control module (TCM) supplies a 5-volt reference signal to the sensor. When the transmission fluid is cold, the sensor resistance is high and the TCM senses a high signal voltage. As the transmission fluid warms, the sensor resistance lowers and the TCM senses lower voltage. The TCM uses the TFT reading in order to control the torque converter clutch (TCC), line pressure adjustments, and temperature compensated shifts. The TFT sensor range is -40 to +150°C (-40 to +304°F).

Conditions for Running the DTC

P0712

The engine is running for 5 seconds.

P0713

Conditions for Setting the DTC

P0712

The TFT sensor is greater than 150°C (302°F) for 12 seconds.

P0713

The TFT is less than -40°C (-40°F) for 1 minute and 20 seconds.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

DTC P0712 and P0713 are type C DTCs.

Diagnostic Aids

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Special Tools

Circuit/System Verification

Start the engine. With the vehicle in PARK and at normal operating temperature, observe the Trans. Fluid Temp. parameter on the scan tool. The Trans. Fluid Temp. should display near the ECT sensor parameter.

Circuit/System Testing

1. Ignition OFF, using the remover J 44257 , disconnect the automatic transmission inline 20-way connector X175 and install the jumper harness J 44152 on the engine side of the AT inline 20-way connector.

Important: When test probing TCM harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 GM terminal test kit. Use of the brown J 35616-6 (1.00 mm) PCM probe in a 0.64 mm terminal will deform the terminal, resulting in intermittent open conditions. The correct probe for TCM harnesses is the light blue J 35616-64B (0.64 mm) probe.

2. Ignition ON, using the light blue probes J 35616-64B, test for 4.9-5.1 V between the TFT Sensor signal circuit jumper harness pin L and a good ground.

⇒	If the voltage is less than the specified range, test the TFT sensor signal circuit for an open, high resistance or short to ground.

Important: If a short to voltage is found, test the TFT sensor for damage.

⇒	If the voltage is greater than the specified range, test the TFT sensor signal circuit for a short to voltage.

3. Using the light blue probes J 35616-64B, test for 4.9-5.1 V between the TFT Sensor signal circuit jumper harness pin L and the TFT low reference circuit jumper harness pin M.

⇒	If the voltage is less than the specified value, test the low reference circuit for an open, high resistance.

4. Remove the jumper harness J 44152 from the engine side of the AT inline 20-way connector and install it on the transmission pass-thru connector.
5. Using the light-blue test probes J 35616-65B from the most current J 35616 GM terminal test kit, test for 3164-3867 Ω at 20°C (68°F) between the TFT Sensor signal circuit jumper harness pin L and the TFT low reference circuit jumper harness pin M. Refer to Transmission Fluid Temperature Sensor Specifications for the resistance at other temperatures.

⇒	If greater than the specified range, test the affected circuits for an open/high resistance. If both circuits test normal, replace the TFT sensor.

⇒	If less than the specified range, test the affected circuits for a shorted together condition. If both circuits test normal, replace the TFT sensor.

6. Test for greater than 10K Ω between the TFT Sensor signal circuit jumper harness pin L and all other circuits of the jumper harness J 44152 , except the TFT low reference circuit jumper harness pin M.

⇒	If less than the specified range, the affected circuits are shorted together. Replace the transmission internal wire harness.

7. Test for greater than 10M Ω from the TFT Sensor signal circuit jumper harness pin L and the TFT low reference circuit jumper harness pin M to the transmission case.

⇒	If less than the specified value, the affected circuit is shorted to the transmission case. Replace the transmission internal wire harness.

8. If all circuits and connections test normal, replace the TCM.

Component Testing

Install the jumper harness J 44152 on the transmission side of the automatic transmission 20-way inline connector X175. Using the most current GM terminal test kit, measure the resistance between the TFT sensor signal circuit and the low reference circuit. Refer to Transmission Fluid Temperature Sensor Specifications.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.