LCT 1000 Allison Transmission
DTC P0711
Circuit Description
The transmission fluid temperature (TFT) sensor is a part of the pressure switch manifold (PSM) assembly, and is located in the transmission oil pan. The TFT sensor is a thermistor, which changes value based on the temperature of the transmission fluid. The transmission control module (TCM) supplies a 5-volt reference voltage signal to the TFT sensor and measures the voltage drop in the circuit. When the transmission is cold, the sensor resistance is high and the TCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The TCM uses this information to control shift quality and torque converter clutch (TCC) apply.
DTC P0711 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0711 Transmission Fluid Temperature (TFT) Sensor Circuit - Performance
Conditions for Running the DTC
* DTC P0712, P0713, P0716, P0717, P0721, and P0722 are not active.
* The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
* Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
* The engine has been running for 2 seconds.
* Engine speed is above 450 RPM and output speed is above 100 RPM.
* The TFT is in the range of -35°C to +149°C (-31°F to +300°F).
Conditions for Setting the DTC
DTC P0711 sets when the TCM detects one of the following conditions:
* The TCM detects a temperature change that is below a set limit when compared to samples of the minimum and maximum temperature values.
* The TFT has an unrealistic temperature change of greater than 10°C (50°F) for 10 occurrences.
* The temperature from start-up decreases 40°C (104°F) or greater within a duration of 6 seconds or greater.
Action Taken When the DTC Sets
* The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
* The TCM freezes shift adapts.
* The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
* The TCM stores DTC P0711 in TCM history.
* The TCM inhibits TCC engagement.
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
* The TFT should rise steadily during warm-up cycles, then stabilize.
* DTC P0218 may set after DTC P0711 has set. Follow the diagnostic table for DTC P0711 before proceeding to the diagnostic for DTC P0218.
* Inspect the wiring for poor electrical connections at the TCM. Inspect 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, massage the wiring harness while watching the test equipment for a change.
* You may have to drive the vehicle in order to experience a condition.
* An open condition at the circuit may allow a ground path internally through this circuit. If this occurs, the TCM sees a temperature that appears to be within normal operation, approximately -22°C (-7.6°F), and initially a code will not be set. However, the transmission will still inhibit shift adapts and TCC operation. It may take several minutes before DTC P0711 is set to indicate a failure.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
4. This step tests 5-volt reference.
6. This step tests the TFT sensor and internal wiring harness.
7. This step tests the resistance of the TFT sensor.
