Circuit Description
The automatic transmission fluid temperature (TFT) sensor is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases, the resistance increases. The powertrain control module (PCM) supplies a 5-volt reference signal to the sensor on the TFT sensor signal circuit and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.
When the PCM detects one of the following unusual conditions, then DTC P0711 sets.
| • | An unrealistically large change in transmission temperature |
| • | A transmission temperature which remains constant for a period of time in which a measurable amount of change is expected |
DTC P0711 is a type C DTC.
Conditions for Running the DTC
| • | No VSS assembly DTCs P0502 or P0503. |
| • | No Transmission Component Slipping DTC P0894. |
| • | The system voltage is 10-18 volts. |
| • | The engine is running for 409 seconds. |
| • | The engine coolant temperature (ECT) is greater than 70°C (158°F) and the temperature has changed by 50°C (90°F) since startup. |
| • | The vehicle speed is greater than 8 km/h (5 mph) for 409 seconds cumulative during the current ignition cycle. |
| • | The TFT at startup is between -40 and +21°C (-40 and +70°F). |
| • | The TFT is between -38 and +151°C (-36 and +304°F). |
| • | The TCC slip speed is greater than 120 RPM for 409 seconds cumulative during the current ignition cycle. |
Conditions for Setting the DTC
DTC P0711 sets if one of the following conditions occurs:
Condition 1
The TFT does not change more than 3°C (5.4°F) for 409 seconds since startup.
Condition 2
The TFT changes more than 20°C (36°F) in 200 milliseconds 14 times within 7 seconds.
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM calculates a default transmission fluid temperature based on engine coolant temperature, intake air temperature and engine run time. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records. |
Conditions for Clearing the DTC
| • | A scan tool can clear the DTC. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for an intermittent short or open condition in the engine wiring harness. The test lamp is used as a resistor in the circuit.
-
This step determines if the PCM or the TFT sensor is causing a steady, unchanging TFT reading.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.3L | ||||
2 | Inspect for correct transmission fluid level. Refer to Transmission Fluid Check . Did you perform the fluid checking procedure? | -- | Go to Step 3 | Go to Transmission Fluid Check | ||||
3 |
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.
Did either of the conditions occur? | -- | Go to Step 4 | Go to Intermittent Conditions in Engine Controls - 4.3L | ||||
4 | Did the scan tool display a condition in which the Trans. Fluid Temp. does not change by more than the specified value in 409 seconds since startup? | 3°C (5.4°F) | Go to Step 6 | Go to Step 5 | ||||
Refer to Automatic Transmission Inline 20-Way Connector End View . Does the scan tool Trans. Fluid Temp. change by more than the specified value? | 20°C (36°F) | Go to Step 7 | Go to Step 8 | |||||
Does the scan tool display the same condition as in Step 4? | -- | Go to Step 11 | Go to Step 10 | |||||
7 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 | ||||
8 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find an intermittent open or short condition? | -- | Go to Step 9 | Go to Step 10 | ||||
9 | Replace the AT wiring harness assembly. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
10 | Replace the TFT sensor, this sensor is part of the TFP manual valve position switch. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.3L. Did you complete the replacement? | -- | Go to Step 12 | -- | ||||
12 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | Go to Step 13 | Go to Step 2 | ||||
13 | With the scan tool, observe the stored information, capture info, and DTC Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.3L | System OK |
