Circuit Description
The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (A/T) wiring harness assembly. 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 CKT 1227 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.
If the PCM detects the TFT sensor resistance has no change, or an unrealistic change in a short amount of time, (multiple changes within seconds) then DTC P0711 sets. DTC P0711 is a type D DTC.
Conditions for Running the DTC
| • | No A/T ISS sensor DTC P0716 or P0717. |
| • | No A/T OSS sensor DTC P0722 or P0723. |
| • | No engine coolant temperature (ECT) DTCs P0117 or P0118. |
| • | No A/T component slipping DTC P1870. |
| • | System voltage is 8.0-18.0 volts. |
| • | The engine is running greater than 300 RPM for at least 35 seconds. |
| • | The TFT is -40° to +21°C (-40° to +70°F) at start up. |
| • | The engine coolant temperature (ECT) is greater than 85°C (185°F). |
| • | ECT has changed at least 55°C (130°F) since start up. |
| • | The vehicle speed is greater than 5 mph for at least 900 seconds (15 minutes). |
| • | The TCC slip speed is greater than 60 RPM for at least 500 seconds (13.3 minutes). |
Conditions for Setting the DTC
DTC P0711 sets if all of the above conditions have been met for Running the DTC and one of the following conditions exist:
| • | The TFT has not changed more than 2.25°C (4°F), in more than 80 seconds (No TFT change). |
| • | The TFT has changed more than 20°C (68°F) 14 times in 7 seconds (unrealistic temperature change). |
Action Taken When the DTC Sets
| • | The PCM does not illuminates the malfunction indicator lamp (MIL). |
| • | The PCM commands increased line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM determines a TFT default transmission temperature (TFT) using the following matrix: |
| - | If the engine run time is less than 60 seconds then default TFT equals the intake air temperature (IAT), plus 5 degrees. |
| - | If the engine coolant temperature (ECT) is less than 85°C (185°F) then default TFT equals IAT plus 10 degrees. |
| - | If the ECT is 85°-110°C (185°-230°F) then default TFT equals ECT plus 10 degrees. |
| - | If the ECT is greater than 110°C (230°F) then default TFT is set to 140°C (284°F) and transmission shift pattern is in hot mode. |
| - | If ECT and TFT DTCs are both set then default TFT is 140°C (284°F). |
| • | The PCM stores DTC P0711 in PCM history. |
Conditions for Clearing the DTC
| • | A scan tool clears the DTC from PCM history. |
| • | The PCM clears the DTC from PCM history if the vehicle completes 40 consecutive warm-up cycles without a non-emission-related diagnostic fault occurring. |
| • | The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM. |
Diagnostic Aids
| • | Inspect the wiring at the PCM, the transmission connector and all other circuit connecting points for the following conditions: |
| - | A backed out terminal |
| - | A damaged terminal |
| - | Reduced terminal tension |
| - | A chafed wire |
| - | A broken wire inside the insulation. |
| - | Moisture intrusion |
| - | Corrosion |
| • | When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. |
| • | First diagnose and clear any engine DTCs or TP sensor DTCs that are present. Then inspect for any transmission DTCs that may have reset. |
| • | DTC P0218 may set approximately 600 seconds after DTC P0711 has set. Follow the diagnostic table for DTC P0711 before proceeding to the diagnostic table for DTC P0218. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for proper A/T fluid level and condition.
-
This step verifies which condition has set DTC P0711.
-
The 12-volt test lamp is used as a fixed resistance.
-
This step ensures that the PCM monitors circuit 1227.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
Perform the Transmission Fluid Checking Procedure. Was the fluid checking procedure performed? | -- | Go to Transmission Fluid Check | ||||||
Important: Before clearing the DTCs, 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 fail conditions occur? | -- | Go to Diagnostic Aids | ||||||
4 | Did the scan tool display an unrealistic TFT change? | -- | ||||||
Does the scan tool TFT display an unrealistic TFT change? | -- | |||||||
Is the scan tool TFT the same as in step 4? | -- | |||||||
7 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming in Engine Controls. Is the replacement complete? | -- | -- | |||||
8 | Replace the TFT sensor. Refer to Wiring Harness Replacement. Is the replacement complete? | -- | -- | |||||
9 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | -- | System OK |
