Circuit Description
The Automatic Transmission Fluid Temperature (TFT) Sensor is a thermistor that controls the signal voltage to the Vehicle Control Module (VCM). The VCM supplies a 5-volt reference signal to the sensor on circuit 1227. When the transmission is fluid is cold, the sensor resistance is high and the VCM senses a high signal voltage. As the TFT warms to normal operating temperature, the sensor resistance decreases and the voltage decreases.
If the VCM detects a continuous open or short to the power in the TFT signal circuit or the TFT Sensor, then DTC P0713 sets. DTC P0713 is a type D DTC. For California emissions vehicles, DTC P0713 is a type B DTC.
Conditions for Setting the DTC
| • | The TFT Sensor indicates a voltage greater than 4.92 volts. |
| • | The ignition is ON. |
| • | All conditions met for 410 seconds. |
Action Taken When the DTC Sets
| • | The VCM uses a TFT default of 140°C (275°F). The scan tool does not display the default temperature. |
| • | The VCM freezes shift adapts from being updated. |
| • | The VCM illuminates the Malfunction Indicator Lamp (MIL) for California Emission vehicles. |
Conditions for Clearing the DTC
| • | For California Emissions only, the VCM turns off the MIL after three consecutive ignition cycles without a failure reported. |
| • | A scan tool can clear the DTC from the VCM history. The VCM clears the DTC from the VCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The VCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the VCM. |
Diagnostic Aids
| • | Inspect the harness for a faulty connection or an open in circuit 1227. |
| • | Inspect the wiring for poor electrical connections at the VCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following problems: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | High voltage in circuit 1227 may also damage the TFT Sensor. |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | The scan tool displays the TFT in degrees. After the transmission operates, the temperature rises steadily to about 100°C (212°F). The temperature then stabilizes. |
| • | Test the TFT Sensor at the various temperatures in order to evaluate the possibility of a skewed (mis-scaled) sensor. Use the Temperature vs Resistance table. A skewed sensor may cause firm shifts or TCC complaints. |
| • | First diagnose and clear any engine DTCs or TP Sensor codes that are present. Then inspect for any transmission DTCs that may have reset. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for higher than normal circuit voltage which may also damage the TFT Sensor.
-
This step simulates a TFT Sensor DTC P0712. If the VCM recognizes the low signal voltage (high temperature), and the scan tool displays 146°C (295°F) or greater, the VCM and the wiring are OK.
-
This step verifies a problem in the TFT Sensor circuit inside the transmission.
-
This step inspects the TFT Sensor and the Automatic Transmission Wiring Harness Assembly (A/T Wiring Harness Assy). Circuit 470 becomes circuit 452 inside the transmission.
-
In step 9 you replace the A/T Wiring Harness Assy. The TFT Sensor is part of the A/T Wiring Harness Assy.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Perform the transmission fluid checking procedure. Refer to Transmission Fluid Check . Did you perform the fluid checking procedure? | -- | -- | |
3 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Does the scan tool display a TFT Sensor signal voltage greater than the specified value? | 4.92 volts | Go to Diagnostic Aids | |
|
Important: Refer to Test Description for information about Step 4. Does the scan tool display a TFT voltage greater than the specified value? | 5.1 volts | |||
5 |
Refer to Electronic Component Description . Is the voltage within the specified value? | 4.9-5.0 Volts | ||
Is the TFT sensor signal voltage less than the specified value? | 0.2 volts | |||
Refer to Electronic Component Description . Is the resistance within the specified values? | 16kΩ at 10°C (50°F) to 133Ω at 110°C (230°F) | Go to Diagnostic Aids | ||
Refer to Changing the Fluid and Filter, in On-Vehicle Service. Did you find a problem? | -- | -- | ||
Replace the A/T Wiring Harness Assy. Refer to Interior Wiring Harness Replacement, in On-Vehicle Service. Is the replacement complete? | -- | -- | ||
10 | Inspect circuit 1227 for high resistance or an open. Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||
11 | Inspect circuit 1227 for a short to voltage B+. Did you find a problem? | -- | ||
12 | Inspect circuit 470 for an open. Refer to Electrical Diagnosis, Section 8. Did you find a problem? | -- | ||
13 | Inspect the VCM for faulty or intermittent connections. Did you find a problem? | -- | ||
14 | Replace the VCM. Refer to VCM Replacement/Programming , Section 6. Is the replacement complete? | -- | ||
15 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
