Circuit Description
The Automatic Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermister within the Automatic Transmission Fluid Pressure (TFP) Manual Valve Position Switch. The TFT controls the signal voltage from the PCM. The PCM supplies a 5 volt reference signal to the TFT sensor on circuit 1227. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the transmission fluid warms, the sensor resistance decreases and the detected voltage decreases. At the transmission's normal operating temperature of 100°C (212°F), the voltage is approximately 1.5 -2 volts.
If the PCM detects a continuous open or short to power in the TFT signal circuit or the TFT sensor in two consecutive ignition cycles, then DTC P0713 sets. DTC P0713 is a type B DTC.
Conditions for Setting the DTC
| • | The system voltage is 10-17 volts. |
| • | The ignition is ON. |
| • | The TFT sensor indicates a voltage greater than 4.94 volts. |
| • | All conditions met for 50 seconds in two consecutive ignition cycles. |
Action Taken When the DTC Sets
| • | The transmission default temperature becomes 135°C (275°F). |
| • | The PCM freezes shift adapts from being updated. |
| • | The PCM illuminates the Malfunction Indicator Lamp (MIL). |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL after three consecutive ignition cycles without a failure reported. |
| • | A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the harness for a faulty connection or an open in circuit 1227 (YEL/BLK). |
| • | Inspect the wiring for poor electrical connections at the PCM. Inspect the wiring at the 20-way harness. Look for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching test equipment for changes. |
| • | The scan tool displays the transmission fluid temperature in degrees. After the transmission is operating, the temperature should rise steadily to about 100°C (212°F). |
| • | Use the Temperature Versus Resistance scale in order to test the TFT sensor at various temperatures. Test the TFT sensor in order to eliminate the possibility of a skewed (mis-scaled) sensor. A skewed sensor can result in firm shifts or TCC complaints. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that a problem exists in the TFT sensor circuit.
-
This step simulates a TFT sensor DTC P0712. If the PCM receives the low signal voltage (indicating high temperature), and the scan tool displays 146°C (296°F) or greater, then the PCM and external wiring are functioning normally.
-
This step tests the TFT sensor and the Automatic Transmission Wiring Harness Assembly.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check , Section 6 | |||||||
2 | Examine the transmission fluid. Refer to Transmission Fluid Check . Did you perform the fluid checking procedure? | -- | Go to Transmission Fluid Check | |||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the 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 voltage? | 4.94 volts | Go to Diagnostic Aids | ||||||||
Does the TFT Sensor signal voltage decrease to less than the specified value? | 0.196 volts | |||||||||
Important: This resistance range is valid at 20°C (68°F). In order to verify the TFT sensor at other temperatures, refer to the Temperature Versus Resistance table. Is the resistance within specifications? | 3088-3941ohms | Go to Diagnostic Aids | ||||||||
6 |
Refer to Transmission Oil Pan Removal. Refer to Electrical Diagnosis, Section 8A. Did you find and correct a problem? | -- | ||||||||
7 |
Important: This resistance range is valid at 20°C (68°F). In order to verify the TFT sensor at other temperatures, refer to the Temperature Versus Resistance table. Is the resistance within specifications? | 3088-3941ohms | Go to Diagnostic Aids | |||||||
8 | Replace TFP Valve Position Switch. Refer to Control Valve Body and Pressure Switch, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||||
9 | Inspect circuit 1227 (YEL/BLK) for an open or a short to Battery Positive Voltage. Refer to Electrical Diagnosis, Section 8. Did you find and correct a problem? | -- | ||||||||
10 | Inspect circuit 455 for an open. Refer to Electrical Diagnosis, Section 8. Did you find and correct a problem? | -- | ||||||||
11 |
Did you find and correct a problem? | -- | ||||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||||
13 |
Has the test run and passed? | -- | System OK |
