For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0712: Transmission Fluid Temperature (TFT) Sensor Circuit Low Voltage
DTC P0713: Transmission Fluid Temperature (TFT) Sensor Circuit High Voltage

### Circuit/System Description

The automatic transmission fluid temperature (TFT) sensor is a 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.

### Conditions for Running the DTC

#### P0712

The engine is running for 5 seconds.

#### P0713

• | No ISS DTCs P0716 or P0717.

• | No OSS DTCs P0722 or P0723.

• | The output shaft speed is greater than 200 RPM for 200 seconds (3 minutes and 20 seconds) cumulative.

• | The TCC slip speed is greater than 120 RPM for 200 seconds (3 minutes and 20 seconds) cumulative.

• | The engine run time is greater than 5 seconds.

### Conditions for Setting the DTC

#### P0712

The TFT sensor is greater than 150°C (302°F) for 10 seconds.

#### P0713

The TFT is less than -40°C (-40°F) for 25 seconds.

### Action Taken When the DTC Sets

DTC P0712 and P0713 are Type C DTCs.

### Conditions for Clearing the DTC

DTCs P0712 and P0713 are Type C DTCs.

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Transmission General Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Transmission Control Module Scan Tool Information

#### Special Tools

• | J 35616 GM-Approved Terminal Test Kit

• | J 44152 Jumper Harness (20 pins)

• | J 45681 Jumper Harness

### 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. Disconnect the AT 20-way inline connector. Using a DMM and the J 35616 GM-approved terminal test kit, measure the voltage at the TFT sensor signal circuit at the engine side of the connector. The voltage should be 4.9-5.1 volts.

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

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

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

2. Using the J 35616 , measure the voltage between the TFT sensor signal circuit and the low reference circuit at the engine side of the AT 20-way inline connector. The voltage should be 4.9-5.1 volts.

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

3. Install the J 45681 jumper harness, on the transmission side of the AT 20-way inline connector. Using the J 35616 , measure the resistance between the TFT sensor signal circuit and the low reference circuit. Refer to Temperature Versus Resistance for the 2.0L or Temperature Versus Resistance for the 2.4L.

⇒ | If the resistance is greater than the specified range for a given temperature, test the TFT sensor signal circuit and the low reference circuit for an open or high resistance.

⇒ | If the resistance is less than the specified range, test the TFT sensor signal circuit and the low reference for a shorted together condition or a faulty TFT sensor.

⇒ | If a shorted together condition is found, replace the transmission wiring harness.

4. Using the J 35616 , measure the resistance between the TFT sensor signal circuit and the transmission case. The resistance should be greater than 10K ohms.

⇒ | If the resistance is less than 10K ohms, test the TFT sensor signal circuit for a short to the transmission case.

⇒ | If a short to the case is found, replace the transmission wiring harness.

5. Using the J 35616 , measure the resistance between the low reference circuit and the transmission case. The resistance should be greater than 10K ohms.

⇒ | If the resistance is less than 10K ohms, test the low reference circuit for a short to the transmission case.

⇒ | If a short to the case is found, replace the transmission wiring harness.

6. Using the J 35616 , measure the resistance between the TFT sensor signal circuit and all other circuits of the J 45681 except the low reference circuit. The resistance should be greater than 10K ohms.

⇒ | If the resistance is less than 10K ohms, replace the transmission wiring harness.

⇒ | If all circuits/connections test normal, test the TFT sensor.

### Component Testing

Install the J 44152 jumper harness (20 pins) on the transmission side of the AT 20-way inline connector. Using the J 35616 measure the resistance between the TFT sensor signal circuit and the low reference circuit. Refer to Temperature Versus Resistance for the 2.0L or Temperature Versus Resistance for the 2.4L for the resistance values.

If the resistance is not within the specified range, replace the transmission wiring harness.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• | Ensure the transmission fluid temperature is between -39 and +149°C (-39 and +300°F) for at least 12.5 seconds.

• | Refer to Control Module References for TCM replacement, setup, and programming.

• | Transmission Internal Electrical Harness Replacement