Allison Automatic Transmission

ALLISON AUTOMATIC TRANSMISSION

DTC P0711





Test 1-5





Test 6-10





Test 11-13

Circuit Description for Allison Automatic Transmission
The Transmission Fluid Temperature (TFT) sensor is a part of the transmission Pressure Switch Manifold (PSM) assembly. The TFT sensor is a thermistor, which changes its value based on temperature. The Transmission Control Module (TCM) supplies a 5 V reference signal to the TFT sensor. When the transmission fluid is cold, the sensor resistance is high and the TCM detects a high signal voltage. As transmission fluid temperature increases, the resistance becomes less, and the signal voltage decreases.
DTC P0711 is a type B DTC.

Conditions for Running the DTC
^ The components are powered and ignition voltage is greater than 9 V and less than 18 V.
^ Engine has been running for 2 seconds.
^ Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
^ Engine speed is above 450 RPM and output speed is above 100 RPM.
^ The transmission fluid temperature is in the range -35°C (-31°F) to 149°C (300°F).

Conditions for Setting the DTC
DTC P0711 sets when the TCM detects one of the following conditions:
^ TCM detects that temperature change is under a set limit when compared to samples taken of the minimum and maximum temperature values.
TCM detects noise in the temperature signal received.
TCM detects a temperature decrease greater then a set limit from start-up.

Action Taken When the DTC Sets
DTC P0711 will be stored in the TCM history.
The TCM uses a TFT default value.
Illuminates MIL when active.

Conditions for Clearing the MIL/DTC
A scan tool can clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
^ Inspect the wiring for poor electrical connections at the TCM. 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, massage the wiring harness while watching the test equipment for a change.
^ You may have to drive the vehicle in order to experience a fault.
^ An open condition at wire 220 may allow a ground path internally through wire 221. If this occurs, the TCM sees a temperature that appears to be within normal operation, about -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 a P0711 code 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 V reference voltage.
5. This step tests for an erratic temperature signal.
6. This step tests the internal wiring harness for opens/shorts.
7. This step tests the external wiring harness for opens/shorts.
9. This step tests the resistance of the TFT sensor.