GM Service Manual Online
For 1990-2009 cars only

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 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

P0713¹

--

Low Reference

--

P0713

P0713¹

--

¹Internal ECM damage may occur if the circuit is shorted to B+.

Circuit/System Description

The transmission fluid temperature (TFT) sensor is a variable resistor that measures the temperature of the transmission fluid. The engine control module (ECM) supplies 5 V to the TFT signal circuit and supplies a ground to the low reference circuit.

The following table illustrates the difference between temperature, resistance, and voltage:

TFT

TFT Resistance

TFT Signal Voltage

Cold

High

High

Warm

Low

Low

Conditions for Running the DTC

P0712

    • The engine speed is above 1,000 RPM for 7 seconds.
    • This DTC runs continuously when the above condition is met.

P0713

    • The engine speed is above 1,000 RPM for 7 seconds.
    • This DTC runs continuously when the above condition is met.

Conditions for Setting the DTC

P0712

The TFT is greater than 145°C (299°F) for more than 5 seconds.

P0713

The TFT is less than -35°C (-31°F) for more than 5 seconds.

Action Taken When the DTC Sets

DTC P0712 and P0713 are Type C DTCs.

Conditions for Clearing the MIL/DTC

DTC P0712 and P0713 are Type C DTCs.

Reference Information

Schematic Reference

Manual Transmission Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Manual Transmission Description and Operation

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

Engine Control Module Scan Tool Information

Circuit/System Verification

  1. Engine running, DTC P0712 or P0713 should not set.
  2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the TFT sensor.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground.
  3. If greater than 5 ohms, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition ON, using a scan tool verify that the TFT sensor parameter is at -40°C (-40°F).
  5. If greater than -40°C (-40°F), test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.

    Note: If the signal circuit of the TFT sensor is shorted to voltage the TFT sensor may be damaged.

  6. Install a 3 A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the TFT sensor parameter is greater than 128°C (262°F).
  7. If less than 128°C (262°F), test the signal circuit of the TFT sensor for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM.
  8. If all circuits test normal, test or replace the TFT sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Transmission Fluid Temperature Sensor Replacement
    •  Engine Control Module Replacement or Engine Control Module Replacement
    •  Engine Control Module Programming and Setup