Circuit Description
The Automatic Transmission Fluid Temperature (TFT) sensor is a negative coefficient thermistor. When the transmission fluid is cold, the sensor resistance is high. As the transmission fluid warms up, the sensor resistance decreases. This diagnostic monitors the TFT circuit. The circuit may be functional, but not in the normal operating range. This diagnostic indicates stuck, erratic, intermittent, or skewed values, indicating poor system performance. The TFT range is -40 to +151°C (-40 to +304°F).
When the PCM detects an intermittent voltage or no voltage change in the TFT sensor circuit, then DTC P0711 sets. DTC P0711 is a Type B DTC.
Conditions for Setting the DTC
| • | No VSS DTCs P0502 or P0503 are set. |
| • | The System Voltage is 10-16 volts. |
| • | The TFT sensor voltage is 0.2-4.92 volts. |
| • | The transmission fluid temperature at start-up is -40 to 21°C (-40 to 69°F). |
| • | The engine run time is more than 5 minutes. |
| • | The vehicle speed is greater than 8 km/h (5 mph) for 7 minutes cumulative. |
| • | The TCC slip is greater than 120 RPM for 7 minutes cumulative. |
| • | The engine coolant temperature is more than 70°C (158°F). |
| • | The engine coolant temperature has changed by 50°C (90°F) since start-up. |
Fail case #1: The change in transmission fluid temperature is less than 1.5°C (2°F) since start-up for 7 minutes.
Fail case #2: The change in transmission fluid temperature is greater than 20°C (36°F) within 0.2 seconds and 14 times within 7 seconds.
Action Taken When the DTC Sets
| • | The PCM turns on the Malfunction Indicator Lamp (MIL) after 2 consecutive ignition cycles with a failure reported. |
| • | The PCM disables shift adapts. |
| • | If the Engine Run Time is less than 3 minutes and: |
| - | Intake Air Temperature (IAT) DTC P0112, P0113, P1111, or P1112 is set, then the default TFT is 0°C (32°F). |
| - | No IAT DTC is set, then the default TFT is set to the IAT saved at start up. |
| • | If the engine run time is greater than 3 minutes, and an Engine Coolant Temperature (ECT) DTC P0117, P0118, P1114, or P1115 is set, then the default TFT is 131°C (268°F). |
| • | If the engine run time is greater than 3 minutes, no ECT DTC is set, and: |
| - | The ECT is less than 45°C (113°F), then the default TFT is 12°C (54°F). |
| - | The ECT is greater than 115°C (239°F), then the default TFT is 131°C (268°F). |
| - | The ECT is 45-115°C (113-239°F) and: |
| - | The IAT DTC P0112, P0113, P1111, or P1112 is set, then the default TFT is set to equal the ECT. |
| - | The IAT at start up is less than 0°C (32°F), then the default TFT is set to ECT minus 10°C (18°F). |
| - | The IAT at start up is greater than 28°C (82°F), then the default TFT is set to ECT plus 10°C (18°F). |
| - | The IAT at start up is 0-28°C (32-82°F), then the default TFT is set to equal ECT. |
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 wiring for poor electrical connections at the PCM. Inspect the wiring for poor electrical connections at the transmission 20-way connector. Look for the following conditions: |
| - | A bent terminal |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Poor terminal tension |
| - | A chafed wire |
| • | Test the TFT sensor at various temperature levels to evaluate the possibility of a skewed (mis-scaled) sensor. |
| • | When diagnosing for an intermittent short or open condition, massage the wiring harness while watching the test equipment for a change. |
| • | Inspect the transmission 20-way connector for transmission fluid. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step ensures that the transmission fluid is at the proper level. Low fluid may cause this DTC to set.
-
You must clear the DTC before running this test. This test is best performed from a cold start. If the DTC does not set, road test the vehicle as instructed in Step 12. If the TFT defaults to a calibrated value, proceed to Step 4.
-
Perform this test in order to detect an intermittent problem. If the transmission fluid is warm, the voltage will rise slowly. A rapid rise or drop in voltage, caused by massaging the harness, indicates an open or short.
-
Perform this step in order to detect an intermittent problem in the transmission harness. The resistance value must be recorded as soon as the ohmmeter is set on MAX. If an open or short to ground occurs, the display indicates a resistance higher than the recorded value. You must use J 39200 DMM.
-
This step detects a short together of circuits 1227 and 452. The ohmmeter displays a resistance lower than the recorded value.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||||||
Has the transmission fluid checking procedure been performed? | -- | Go to Transmission Fluid Check | ||||||||||
Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data. Does the TFT Sensor Temperature default to a calibrated value? | -- | |||||||||||
Does the TFT voltage indicate an unrealistic change when you massage the harness and connectors? | -- | |||||||||||
In the MAX position, does the ohmmeter display a value higher than the recorded value? | -- | |||||||||||
In the MIN position, does the ohmmeter display a value lower than the recorded value | -- | -- | ||||||||||
7 |
Refer to Electrical diagnosis, Section 8. Did you find and correct a problem? | -- | ||||||||||
8 | Inspect the Automatic Transmission Wiring Harness Assembly. Did you find a short to ground, a short together, or an open? | -- | ||||||||||
9 | Replace the A/T Wiring Harness Assy. Refer to Solenoids and Wiring Harness, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||||||
10 | Replace the TFT Sensor. Refer to Solenoids and Wiring Harness, in On-Vehicle Service. Is the replacement complete? | -- | -- | |||||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming , Section 6. Is the replacement complete? | -- | -- | |||||||||
12 | In order to verify your repair, perform the following procedure:
Has the test run and passed? | -- | System OK |
