DTC P0712 Gas
Circuit Description
The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (AT) 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 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 a continuous short to ground in the TFT sensor or signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.
Conditions for Running the DTC
| • | The engine is running for greater than 7 seconds. |
| • | System voltage is 8-18 volts. |
| • | No TFT sensor DTC P0713. |
Conditions for Setting the DTC
| • | The TFT sensor indicates a voltage of less than 0.14 volts. |
| • | All conditions are met for 17 seconds. |
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM commands increased line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM determines a default transmission fluid temperature (TFT) using the following: |
| - | If the engine run time is less than 60 seconds, then default transmission fluid temperature equals 47°C (117°F). |
| - | If ECT is less than 20°C (68°F), then default transmission fluid temperature equals intake air temperature. |
| - | If the ECT is 20-110°C (68-230°F), then default transmission fluid temperature equals ECT. |
| - | If the ECT is greater than 110°C (230°F), then default transmission fluid temperature 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 transmission fluid temperature is 140°C (284°F). |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records. |
| • | The PCM stores DTC P0712 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 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
| • | DTC P0712 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine. |
| • | Verify the customer driving habits, trailer towing, weight, or towing in OVERDRIVE. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the fault exists.
-
This step tests for an internal fault within the transmission by creating an open.
-
This step inspects the TFT sensor signal circuit (CKT 1227) of the AT wiring harness assembly for being shorted to ground.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 8.1L |
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Was the Transmission Fluid Checking Procedure performed? | -- | Go to Step 3 | 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. Does the scan tool indicate that the TFT sensor signal voltage is less than the specified value? | 0.14 V | Go to Step 4 | Go to Intermittent Conditions in Engine Controls - 8.1L | |
Does the scan tool indicate that the TFT sensor signal voltage is greater than the specified value? | 4.92 V | Go to Step 5 | Go to Step 9 | |
5 |
Refer to Electronic Component Description . Does the resistance measure within the specified values? | 16 K ohms at -10°C (14°F) to 133 ohms at 110°C (230°F) | Go to Step 6 | Go to Step 7 |
Measure the resistance between terminal L and a good ground on the transmission case. Does the resistance measure less than the specified value? | 50 K ohms | Go to Step 7 | Go to Intermittent Conditions in Engine Controls - 8.1L | |
7 |
Does the resistance measure less than the specified value? | 50 K ohms | Go to Step 10 | Go to Step 8 |
8 | Replace the TFT sensor. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
9 | Test the TFT sensor signal circuit (CKT 1227) of the TFT sensor for a short to ground. 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 |
10 | Replace the AT wiring harness assembly. 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 - 8.1L. 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? | -- | System OK | Go to Step 1 |
DTC P0712 Diesel
Circuit Description
The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (AT) 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 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. DTC P0712 is a type C DTC.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The TFT sensor indicates a voltage less than 0.14 volts. |
| • | All conditions are met for 15 seconds. |
Action Taken When the DTC Sets
| • | The PCM does not illuminate the malfunction indicator lamp (MIL). |
| • | The PCM commands increased line pressure. |
| • | The PCM freezes shift adapts. |
| • | The PCM determines a transmission fluid temperature default using the following: |
| - | If the ECT is -30 to +110°C (-22 to +230°F) then default transmission fluid temperature equals ECT plus 10 degrees. |
| - | If the ECT is greater 110°C (230°F) then default transmission fluid temperature 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 transmission fluid temperature is 140°C (284°F). |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records. |
| • | The PCM stores DTC P0712 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 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
| • | DTC P0712 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine. |
| • | DTC P0218 may set approximately 600 seconds (10 minutes) after DTC P0712 has set. Follow the diagnostic table for DTC P0712 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 verifies the fault exists.
-
This step tests for an internal fault within the transmission by creating an open.
-
This step inspects the TFT sensor signal circuit of the AT wiring harness assembly for being shorted to ground.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Engine Controls in Engine Controls - 6.5L |
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Was the Transmission Fluid Checking Procedure performed? | -- | Go to Step 3 | Go to Transmission Fluid Check |
Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases Failure Records from the PCM. Does the scan tool display a TFT sensor voltage less than the specified value? | 0.13 V | Go to Step 4 | Go to Diagnostic Aids | |
Does the scan tool display a TFT sensor voltage greater than the specified value? | 4.92 V | Go to Step 5 | Go to Step 9 | |
5 |
Refer to Electronic Component Description . Does the resistance measure within specified values? | 16 K ohms at 10°C (50°F) to 133 ohms at 110°C (230°F) | Go to Step 6 | Go to Step 7 |
Measure the resistance between terminal L and a good ground on the transmission case. Does the resistance measure less than the specified value? | 50 K ohms | Go to Step 10 | Go to Intermittent Conditions in Engine Controls - 6.5L | |
7 |
Does the resistance measure less than the specified value? | 50 K ohms | Go to Step 10 | Go to Step 8 |
8 | Replace the TFT sensor. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- |
9 | Test the TFT sensor signal circuit (CKT 1227) for a short to ground between the PCM connector C1-C9 and the AT inline 20-way connector. 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 |
10 | Replace the automatic transmission wiring harness assembly. 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 - 6.5L. 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? | -- | System OK | Go to Step 1 |
