Circuit Description
The Transmission Fluid Temperature (TFT) sensor is part of the automatic transmission internal wiring harness assembly. The TFT sensor is a thermistor, which is a type of resistor that changes value when the temperature changes. The sensor has a negative temperature coefficient, which means that as the temperature increases, the sensors internal resistance decreases. As the temperature decreases, the sensors internal resistance increases.
When the transmission fluid is cold, the sensor's resistance is high and the TCM detects a high signal voltage. As the fluid temperature increases, the internal resistance of the sensor decreases, which in turn lowers the signal voltage.
This diagnostic monitors the TFT sensor circuit. The circuit may be functional, but not in normal operating range. The diagnostic indicates stuck, erratic, intermittent, skewed or inaccurate values, indicating poor system performance. The TFT sensor's range is -40 to +51°C.
If the TCM detects a rapid or no voltage change in the TFT sensor circuit, then DTC P0711 sets, which is a type 'C' DTC.
Conditions for Running the DTC
| • | Ignition voltage is between 8-18 volts. |
| • | Engine speed is between 450-6,800 RPM for at least 5 seconds. |
| • | The following DTCs are not set: |
| - | P0115 - GMLAN Engine Coolant Temperature Fault (No valid GMLAN signal) |
| - | P0716 or P0717 - Transmission Input Speed Sensor |
| - | P0722 or P0723 - Transmission Output Speed Sensor |
| • | DTC P0711 has not passed in the current ignition cycle. |
| • | Engine run time is greater than 5 seconds. |
| • | The transmission fluid temperature is -39 to +149°C. |
| • | For conditions 1 and 2 under 'Conditions for Setting the DTC': |
| - | The engine coolant temperature is greater than 70°C and has changed by at least 50°C since engine start-up. |
| - | Transmission torque converter clutch slip speed is 120 RPM or greater for 600 seconds (10 minutes). |
Conditions for Setting the DTC
One of the following three conditions occurs for this DTC P0711 to set.
Condition 1
| • | The transmission fluid temperature at engine start-up is -40 to +21°C. |
| • | The vehicle speed is greater than 8 km/h for 900 seconds (15 minutes) cumulatively. |
| • | The transmission fluid temperature has not changed by more than 2°C since engine start-up for 100 seconds. |
Condition 2
| • | The transmission fluid temperature at engine start-up is 129 to +150°C. |
| • | The vehicle speed is greater than 8 km/h for 900 seconds (15 minutes) cumulatively. |
| • | The transmission fluid temperature has not changed by more than 2°C since engine start-up for 100 seconds. |
Condition 3
The transmission fluid temperature has changed by 20°C or greater within 250 milliseconds; 14 times in 7 seconds.
Action Taken When the DTC Sets
| • | The TCM does not request the Powertrain Interface Module (PIM) to illuminate the Check Powertrain Malfunction Indicator Lamp (MIL). |
| • | The TCM records the operating conditions when the 'Conditions for Setting the DTC' are met. The TCM stores this information as a Failure Record. |
| • | The TCM calculates a default transmission fluid temperature based on engine coolant temperature, intake air temperature and engine run time. |
| • | The TCM freezes the transmission adaptive learning function. |
| • | The TCM stores DTC P0711 into TCM history. |
Conditions for Clearing the DTC
| • | Tech 2 can clear the DTC. |
| • | The TCM clears the DTC from its memory (history DTC) if the vehicle completes 40 warm-up cycles without a non-emission related DTC occurring. |
| • | The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes. |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
2. Disconnecting the brake switch connector and jumping the circuit while observing a status change on the Tech 2, isolates the brake switch as the source of the DTC.
4. Checks whether the fault is in the vehicle wiring or in the transmission internal wiring harness.
5. Checks for an intermittent open circuit in the TFT sensor signal and low reference circuits.
8. Checks for an intermittent internal short of the sensor signal and low reference circuits.
10. Checks for an intermittent short to ground in either the sensor signal or low reference circuits.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics For information on testing wiring faults, refer to Wiring Systems. | ||||||||||
1 | Has the Diagnostic System Check - Automatic Transmission been completed? | -- | Go to Step 2 | |||||||
2 |
Did you perform the fluid checking procedure and is the level now OK? | -- | Go to Step 3 | Go to Transmission Fluid Check | ||||||
3 |
Did either of the above conditions occur? | -- | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
4 |
Does the TFT change by greater than the specified value? | 20°C | Go to Step 5 | Transmission fluid temperature sensor faulty. Replace transmission internal wiring harness assembly. Refer to Transmission Internal Electrical Harness Replacement | ||||||
5 |
Does either check indicate an intermittent open circuit in the transmission wiring harness? | -- | Repair open in relevant circuit. Go to Step 9 | Go to Step 6 | ||||||
6 |
Does either check indicate an intermittent internal short circuit in the transmission wiring harness? | -- | Repair internal short circuit in relevant circuit. Go to Step 9 | Go to Step 7 | ||||||
7 |
Does either check indicate an intermittent short to ground in the transmission wiring harness? | -- | Repair short to ground in relevant circuit. Go to Step 9 | Go to Step 8 | ||||||
8 | Replace the TCM. Refer to Transmission Control Module Replacement. Is the replacement complete? | -- | Go to Step 9 | -- | ||||||
9 | Perform the following procedure to verify the repair:
Has the test run and passed? | -- | System OK | Go to Step 2 | ||||||
When all diagnosis and repairs are completed, clear all DTCs and verify correct operation. | ||||||||||
