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 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 volts 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.

⇒ | 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.

3. Ignition ON, using a scan tool verify that the TFT sensor parameter is at -40°C (-40°F).

⇒ | 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.

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

4. Install a 3-amp 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).

⇒ | 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.

5. 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