Automatic Transaxle - 4t65-e - DTC p0218 to DTC p0748 Buick LaCrosse I

Scheme 1

Circuit Description

Transmission fluid is drawn from the bottom pan through the filter, case assembly, channel plate assembly, control valve body assembly and into the oil pump assembly. The pump is mounted on the control valve body assembly. Fluid pressure leaving the pump is controlled by the pressure regulator valve and becomes the main supply of line pressure to the various components and hydraulic circuits.

Hot fluid from the torque converter flows through the torque converter clutch (TCC) control valve into the cooler lines to the oil cooler located in the vehicle radiator and auxiliary cooler, if equipped. Cool fluid then returns to lubricate the final drive assembly and other components along the output shaft.

When the transmission control module (TCM) detects high transmission fluid temperature for an extended period of time, then DTC P0218 sets. DTC P0218 is a type C DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC

DTC P0218 Transmission Fluid Overtemperature

Conditions for Running the DTC

The transmission fluid temperature is between 39°C (38°F) and 149°C (300°F) for 5 seconds.

Conditions for Setting the DTC

The transmission fluid temperature is 140°C (286°F) or more for 1 minute.

Action Taken When the DTC Sets

1. The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
2. TRANS HOT-IDLE ENGINE message displays on the Driver Information Center
3. The TCM freezes transmission adaptive functions.
4. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
5. The TCM stores DTC P0218 in TCM history.

Conditions for Clearing the DTC

1. The TCM clears the DIC message when the condition no longer exists.
2. A scan tool can clear the DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

Diagnostic Aids

Ask the customer about possible overloading, exceeding the trailer towing limit or towing in overdrive.

Test Description

The number below refers to the step number on the diagnostic table.

1. 2: A low fluid level may cause an overtemperature condition.

DTC P0218 (3.6L)

Scheme 2

Transmission fluid is drawn from the bottom pan through the filter, case assembly, channel plate assembly, control valve body assembly and into the oil pump assembly. The pump is mounted on the control valve body assembly. Fluid pressure leaving the pump is controlled by the pressure regulator valve and becomes the main supply of line pressure to the various components and hydraulic circuits.

Hot fluid from the torque converter flows through the torque converter clutch (TCC) control valve into the cooler lines to the oil cooler located in the vehicle radiator and auxiliary cooler, if equipped. Cool fluid then returns to lubricate the final drive assembly and other components along the output shaft.

When the powertrain control module (PCM) detects high transmission fluid temperature for an extended period of time, then DTC P0218 sets. DTC P0218 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0218 Transmission Fluid Overtemperature

No TFT sensor DTC P0711, P0712 or P0713.

The transmission fluid temperature is 140°C (284°F) or more for 1 minute.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. TRANS HOT-IDLE ENGINE message displays on the Driver Information Center.
3. The PCM freezes transmission adaptive functions.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame Records.
5. The PCM stores DTC P0218 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

Ask the customer about possible overloading, exceeding the trailer towing limit or towing in overdrive.

The number below refers to the step number on the diagnostic table.

1. 2: A low fluid level may cause an overtemperature condition.

DTC P0218 (3.8L)

Scheme 3

The vehicle speed sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case extension and a toothed vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in the pickup coil that is proportional to vehicle speed. The powertrain control module (PCM) uses this signal in order to calculate vehicle speed, shift timing and gear ratios.

If the PCM detects a low vehicle speed with a high engine speed while in a drive range, then DTC P0502 sets. DTC P0502 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0502 Vehicle Speed Sensor (VSS) Circuit Low Voltage

1. No MAP sensor DTC P0107 or P0108.
2. No ISS DTC P0716 or P0717.
3. The engine is running for greater than 5 seconds and not in fuel cut off.
4. The TP indicated angle is 12 percent or greater.
5. The engine torque is 68-400 N.m (50-300 lb ft).
6. The input shaft speed is 1,500 RPM or greater.
7. The transmission fluid temperature is 0°C (32°F) or more.
8. The TCC slip speed is 0 RPM or more.

The output shaft speed is 150 RPM or less for 5 seconds.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM freezes transmission adaptive functions.
3. The PCM calculates vehicle speed from the input speed sensor for shift timing.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
5. The PCM stores DTC P0502 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.
2. 4: This step tests the VSS circuit for correct resistance.

DTC P0502 (3.8L)

The vehicle speed sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case extension and a toothed vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in the pickup coil that is proportional to vehicle speed. The PCM uses this signal in order to calculate vehicle speed, shift timing and gear ratios.

If the PCM detects a large change in vehicle speed in a short period of time, then DTC P0503 sets. DTC P0503 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0503 Vehicle Speed Sensor (VSS) Circuit Intermittent

1. The time since the last range change is 6 seconds or more.
2. No output shaft speed rise greater than 250 RPM for 2 seconds.

The output shaft speed drops 1,500 RPM or more for 2 seconds.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM freezes transmission adaptive functions.
3. The PCM calculates vehicle speed from the input speed sensor for shift timing.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
5. The PCM stores DTC P0503 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.
2. 4: This step tests the VSS circuit for correct resistance.

DTC P0503 (3.8L)

Scheme 4

The transmission control module (TCM) continuously monitors the system voltage on the Ignition 1 and the battery circuits. Lower than normal voltage may be inadequate to operate the transmission control solenoids properly. Improper solenoid operation may cause erratic transmission operation and tie-up conditions, which may result in internal damage.

When the TCM detects low voltage, DTC P0562 sets. DTC P0562 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0562 System Voltage Low

The engine speed is 1,200 RPM or more for 5 seconds.

The TCM detects system voltage 11 volts or less for 10 seconds.

1. The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
2. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM records this information as a Failure Record.
3. The TCM stores DTC P0562 in TCM history.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

1. Observe the driver information center (DIC) messaging that would indicate the electrical system requires service.
2. Inspect for the following conditions: Loose or damaged terminals at the generator Loose or worn generator drive belt

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests the charging system voltage with a nominal load.
2. 5: This step obtains the ignition voltage measurement reported by the TCM.
3. 6: This step tests the voltage drop from the battery and ignition voltage input at the TCM.
4. 10: This step tests the voltage drop from the ground terminals of the TCM to the ground terminal of the battery.

DTC P0562 (3.6L)

The transmission control module (TCM) continuously monitors the system voltage on the Ignition 1 and the battery circuits. Higher than normal voltage may cause the solenoids inside the transmission to operate improperly or damage solid-state components inside the TCM.

When the TCM detects high voltage, DTC P0563 sets. DTC P0563 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0563 System Voltage High

The ignition is ON.

The TCM detects system voltage 18 volts or more for 10 seconds.

1. The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
2. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM records this information as a Failure Record.
3. The TCM stores DTC P0563 in TCM history.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non emission related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

1. Observe the driver information center (DIC) messaging that would indicate the electrical system requires service.
2. Use the scan tool in order to inspect all other modules for voltage related DTCs.
3. Running the engine with a battery charger attached may cause DTC P0563 to set. Inspect the charging circuit for high resistance. Inspect the vehicle battery for open or sulfated cells.

The numbers below refer to the step numbers on the diagnostic table.

1. 4: This step tests the charging system voltage with a minimal load.
2. 5: This step obtains the ignition voltage measurement reported by the TCM.

DTC P0563 (3.6L)

The internal fault detection is handled inside the transmission control module (TCM). No external circuits are involved.

DTC Descriptors

This diagnostic procedure supports the following DTCs

1. DTC P0601 Transmission Control Module (TCM) Read Only Memory (ROM)
2. DTC P0602 Transmission Control Module (TCM) Not Programmed
3. DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset
4. DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM)

The TCM runs the program to detect an internal fault when the engine is running. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

The TCM has detected an internal malfunction.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
2. The TCM commands an immediate landing to 2nd gear (P0601, P0602, P0603 and P0604).
3. The TCM commands an immediate landing to 2nd gear (P0602).
4. The TCM commands maximum line pressure.
5. The TCM forces the TCC OFF.
6. The TCM inhibits TCC engagement.
7. The TCM freezes transmission adaptive functions.
8. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record.
9. The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame.

1. The ECM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
2. A scan tool can clear the DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM.

The number below refers to the step number on the diagnostic table.

1. 2: A DTC P0602 indicates the TCM is not programmed.

DTC P0601, P0602, P0603 or P0604 (3.6L)

While the vehicle is being driven, engine and transmission data accumulates in a random access memory (RAM) device, which cannot store data reliably when the transmission control module (TCM) powers down. Before the TCM powers down, the data is copied from RAM to an electrically-erasable programmable read-only memory (EEPROM) device, sometime referred to as non-volatile memory (NVM). Both the RAM and the EEPROM are inside the TCM. A normal function of the TCM programming is to test the EEPROM at TCM power-down by copying test data from RAM to the EEPROM and then comparing the two copies. If they do not match, DTC P062F will set. DTC P062F is a type A DTC.

This diagnostic procedure supports the following DTC

DTC P062F Internal Control Module EEPROM Error

The ignition is ON.

The TCM detects a checksum error when the RAM and EEPROM test data are compared.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL).
2. The TCM commands soft landing to 2nd gear.
3. The TCM commands maximum line pressure.
4. The TCM inhibits the TCC solenoid and commands TCC OFF.
5. The TCM freezes transmission adaptive functions.
6. The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame and Failure Records.
7. The TCM stores DTC P062F in TCM history.

1. The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
2. A scan tool can clear the DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM.

TCM reprogramming may cause P062F to set.

The number below refers to the step number on the diagnostic table.

1. 2: Performing this step helps verify that an external anomaly, such as Electromagnetic Interference (EMI), did not cause the code to set originally.

DTC P062F (3.6L)

Scheme 5

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor. When the transmission fluid is cold, the sensor resistance is high. As the transmission fluid warms up, the sensor resistance decreases. This diagnostic monitors the TFT sensor circuit. The circuit may be functional but not in the normal operating range. This diagnostic indicates stuck, erratic, intermittent or skewed values, resulting in reduced system performance. The TFT sensor range is -40 to +151°C (-40 to +304°F).

If the transmission control module (TCM) detects an intermittent voltage or no voltage change in the TFT sensor circuit, then DTC P0711 sets. DTC P0711 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0711 Transmission Fluid Temperature (TFT) Sensor Performance

1. No ECT DTC P0117 or P0118.
2. No ISS DTCs P0716 or P0717.
3. No VSS DTC P0722 or P0723.
4. DTC P0711 has not passed this ignition cycle.
5. The engine coolant temperature is at least 70°C (158°F) and has changed by 55°C (99°F) since start up for Condition 1 and Condition 2.
6. The transmission fluid temperature is -39°C to 149°C (38°F to 300°F).
7. The vehicle speed is 8 km/h (5 mph) or more for at least 5 minutes cumulative for Condition 1 and Condition 2.
8. The TCC slip is 120 RPM or more for at least 5 minutes cumulative for Condition 1.
9. The calc. throttle position is between 8 and 90 percent for Condition 3.
10. The engine torque is 50 N.m (37 lb ft) or more for Condtion 3.
11. The vehicle speed is 8 km/h (5 mph) or more for Condition 3.
12. The engine speed is greater than 500 RPM for Condition 3.

DTC P0711 sets when one of the following conditions occurs

Condition 1

The change in transmission fluid temperature is 2°C (4°F) or less when the TFT is -39 to +20°C (-38 to +66°F) at start up for 80 seconds.

Condition 2

The change in transmission fluid temperature is 2°C (4°F) when the TFT is 129°C-149°C (264°F-300°F) at start up for 80 seconds continuous.

Condition 3

The change in transmission fluid temperature is 20°C (68°F) or less after a predetermined time.

1. The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
2. The TCM freezes transmission adaptive functions.
3. The TCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
5. The TCM stores DTC P0711 in TCM history.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refers to the step numbers on the diagnostic table.

1. 3: This step attempts to repeat the condition that set the DTC.
2. 5: This step attempts to repeat the condition in the engine wiring harness.
3. 6: This step determines if a condition exists with the TCM or TFT sensor.

DTC P0711 (3.6L)

Scheme 6

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor. When the transmission fluid is cold, the sensor resistance is high. As the transmission fluid warms up, the sensor resistance decreases. This diagnostic monitors the TFT sensor circuit. The circuit may be functional but not in the normal operating range. This diagnostic indicates stuck, erratic, intermittent or skewed values, resulting in reduced system performance. The TFT sensor range is -40 to +151°C (-40 to +304°F).

If the powertrain control module (PCM) detects an intermittent voltage or no voltage change in the TFT sensor circuit, then DTC P0711 sets. DTC P0711 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0711 Transmission Fluid Temperature (TFT) Sensor Performance

1. No ECT DTCs P0117 or P0118.
2. No VSS DTCs P0502 or P0503.
3. No ISS DTCs P0716 or P0717.
4. The engine run time is 5 minutes or more.
5. The engine coolant temperature is at least 84°C (183°F) and has changed 55°C (99°F) since start up.
6. The TFT sensor voltage is 0.2-4.92 volts.
7. The transmission fluid temperature at start-up is -40 to +21°C (-40 to +69°F).
8. The vehicle speed is 8 km/h (5 mph) or more for at least 6 minutes and 49 seconds cumulative.
9. The TCC slip is 80 RPM or more for at least 6 minutes and 49 seconds cumulative.

DTC P0711 sets when one of the following conditions occurs

The change in transmission fluid temperature is 1.5°C (2°F) or less since start-up for at least 6 minutes and 49 seconds continuous.

The change in transmission fluid temperature is 20°C (36°F) or more 14 times within 7 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM freezes transmission adaptive functions.
3. The PCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0711 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step attempts to repeat the condition that set the DTC.
2. 5: This step attempts to repeat the condition in the engine wiring harness.
3. 6: This step determines if a condition exists with the PCM or TFT sensor.

DTC P0711 (3.8L)

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The TCM provides a 5 volt reference to the sensor circuit. A high fluid temperature or a short to ground on the signal circuit results in low signal voltage. The TFT sensor operating range is -40 to +151°C (-40 to +304°F).

If the TCM detects a continuous short to ground in the TFT sensor signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Voltage

The engine speed is greater than 500 RPM for 5 seconds.

The TCM detects a TFT greater than 150°C (302°F) for 12 seconds.

1. The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
2. The TCM freezes transmission adaptive functions.
3. The TCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
5. The TCM stores DTC P0712 in TCM history.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refers to the step numbers on the diagnostic table.

1. 2: A value greater than 150°C (302°F) indicates the fault is present. A value below 150°C (302°F) indicates the fault is intermittent.
2. 3: A value less than -40°C (-40°F) indicates the fault is in the transmission side.
3. 5: For resistance at other temperatures, refer to Transmission Fluid Temperature (TFT) Sensor Specifications.

DTC P0712 (3.6L)

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The PCM provides a 5 volt reference to the sensor circuit. A high fluid temperature or a short to ground on the signal circuit results in low signal voltage. The TFT sensor operating range is -40 to +151°C (-40 to +304°F).

If the PCM detects a continuous short to ground in the TFT sensor signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0712 Transmission Fluid Temperature (TFT) Sensor Circuit Low Voltage

The ignition is ON.

The PCM detects a TFT sensor voltage of 0.2 volts or less for 10 seconds.

1. The PCM does not turn on the malfunction indicator lamp (MIL).
2. The PCM freezes transmission adaptive functions.
3. The PCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0712 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: A value below 0.2 volts indicates the fault is present. A value above 0.2 volts indicates the fault is intermittent.
2. 3: A value greater than 4.9 volts indicates the fault is in the transmission side.
3. 5: For resistance at other temperatures, check Transmission Fluid Temperature (TFT) Sensor Specifications.

DTC P0712 (3.8L)

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The TCM provides a 5 volt reference to the sensor. A low fluid temperature, an open TFT sensor or sensor circuit results in high signal voltage. The TFT operating range is -40 to +151°C (-40 to +304°F).

If the TCM detects a continuous open or a short to voltage on the TFT sensor circuit, then DTC P0713 sets. DTC P0713 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Voltage

1. No ISS DTC P0716 or P0717.
2. No OSS DTC P0722 or P0723.
3. The engine speed is greater than 500 RPM for 5 seconds.
4. The output speed is 70 RPM or greater for 200 seconds cumulatively.
5. The TCC slip speed is 120 RPM or greater for 200 seconds cumulatively.

The TCM detects a TFT of less than -40°C (-40°F) for 80 seconds.

1. The TCM does not request the ECM to illuminate the malfunction indicator lamp (MIL).
2. The TCM freezes transmission adaptive functions.
3. The TCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
5. The TCM stores DTC P0713 in TCM history.

1. A scan tool can clear the DTC.
2. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A value of 4.9-5.0 volts indicates the TCM and engine side of the wiring are good.
2. 6: A short to voltage greater than 5 volts would cause the TFT sensor to open.
3. 9: A short to the TFT sensor signal circuit and any other circuits in the transmission harness could cause the TFT sensor to open.

DTC P0713 (3.6L)

The automatic transmission fluid temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. The PCM provides a 5 volt reference to the sensor. A low fluid temperature, an open TFT sensor or sensor circuit results in high signal voltage. The TFT operating range is -40 to +151°C (-40 to +304°F).

If the PCM detects a continuous open or a short to voltage on the TFT sensor circuit, then DTC P0713 sets. DTC P0713 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0713 Transmission Fluid Temperature (TFT) Sensor Circuit High Voltage

The ignition is ON.

The PCM detects a TFT sensor voltage 4.92 volts or more for 6 minutes and 40 seconds continuous.

1. The PCM does not turn on the malfunction indicator lamp (MIL).
2. The PCM freezes transmission adaptive functions.
3. The PCM calculates a default TFT from the ECT sensor and the IAT sensor.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0713 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A value of 4.9-5.0 volts indicates the PCM and engine side of the wiring are good.
2. 6: A short to voltage greater than 5 volts would cause the TFT sensor to open.
3. 9: A short to the TFT sensor signal circuit and any other circuits in the transmission harness could cause the TFT sensor to open.

DTC P0713 (3.8L)

Scheme 7

The automatic transmission input speed sensor (ISS) is a permanent magnet with a coil of wire wound around it. The ISS mounts in the case cover facing the reluctor wheel of the input shaft. As the reluctor wheel is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

There is a fixed air gap between the sensor and the teeth on the sensor reluctor wheel. The ISS input is used by the transmission control module (TCM) in order to control line pressure, torque converter clutch (TCC) apply and release and transmission shift patterns. This sensor is also used to calculate the appropriate gear ratios and TCC slippage.

This diagnostic indicates stuck, erratic or intermittent conditions in the system.

If the TCM detects an unrealistically large change in the ISS high signal in a short period of time, then DTC P0716 sets. DTC P0716 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0716 Input Speed Sensor Performance

1. No TP sensor DTC P0121, P0122 or P0123.
2. No ISS DTC P0717.
3. No OSS DTC P0722 or P0723.
4. No 1-2 shift solenoid valve performance DTC P0752.
5. No 1-2 shift solenoid electrical DTC P0973 or P0974.
6. The engine speed is greater than 500 RPM for 5 seconds.
7. The ISS is 1050 RPM or more for at least 2 seconds.
8. A change in ISS is 500 RPM or less for at least 2 seconds.
9. The vehicle speed is 16 km/h (10 mph) or greater.
10. The calc. throttle position is 8 percent or more.
11. The engine torque is greater than 50 N.m (37 lb ft).

The input shaft speed decreases by 1,000 RPM or more for 3.25 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM calculates input speed from engine speed and gear ratio.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
6. The TCM stores DTC P0716 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL during the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A Yes answer indicates that the transmission side of the circuit is functioning properly.
2. 4: Although the resistance is within specification in Step 3, there may be a short to ground or a short to voltage condition.
3. 8: This step begins the transmission harness diagnosis.

DTC P0716 (3.6L)

DTC P0716 (3.8L)

s

Scheme 8

The automatic transmission input speed sensor (ISS) is a permanent magnet with a coil of wire wound around it. The ISS mounts in the case cover facing the reluctor wheel of the input shaft. As the reluctor wheel is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

There is a fixed air gap between the sensor and the teeth on the sensor reluctor wheel. The ISS input is used by the powertrain control module (PCM) in order to control line pressure, torque converter clutch (TCC) apply and release and transmission shift patterns. This sensor is also used to calculate the appropriate gear ratios and TCC slippage.

This diagnostic indicates stuck, erratic or intermittent conditions in the system.

If the PCM detects an unrealistically large change in the ISS high signal in a short period of time, then DTC P0716 sets. DTC P0716 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0716 Input Speed Sensor Performance

1. No VSS DTC P0502 or P0503.
2. No ISS DTC P0717.
3. DTC P0717 has passed this ignition cycle.
4. No 1-2 shift solenoid valve DTC P0751, P0752 or P0753.
5. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
6. The TP indicated angle is 14 percent or greater.
7. The vehicle speed is 8 km/h (5 mph) or greater.

The input shaft speed changes by 1,300 RPM or more for 0.8 seconds.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM freezes transmission adaptive functions.
3. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
4. The PCM stores DTC P0716 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A Yes answer indicates that the transmission side of the circuit is functioning properly.
2. 4: Although the resistance is within specification in Step 3, there may be a short to ground or a short to voltage condition.
3. 8: This step begins the transmission harness diagnosis.

DTC P0716 (3.8L)

The automatic transmission input speed sensor (ISS) is a permanent magnet with a coil of wire wound around it. The ISS mounts in the case cover facing the reluctor wheel of the input shaft. As the reluctor wheel is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

There is a fixed air gap between the sensor and the teeth on the sensor reluctor wheel. The ISS input is used by the TCM in order to control line pressure, TCC apply and release and transmission shift patterns. This sensor is also used to calculate the gear ratios and TCC slippage.

If the TCM detects a low input speed while the vehicle and engine speeds are high, then DTC P0717 sets. DTC P0717 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0717 Input Speed Sensor Circuit Low Voltage

1. No ISS DTC P0717.
2. No OSS DTC P0722 or P0723.
3. The engine speed is greater than 500 RPM for 5 seconds.
4. The vehicle speed is 16 km/h (10 mph) or greater.
5. The engine torque is greater than 50 N.m (37 lb ft).

The input shaft speed is less than 100 RPM for 4.5 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM calculates input speed from engine speed and gear ratio.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
6. The TCM stores DTC P0717 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL during the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A Yes answer indicates that the transmission side of the circuit is functioning properly.
2. 4: Although the resistance is within specification in Step 3, there may be a short to ground or a short to voltage condition.
3. 8: This step begins the transmission harness diagnosis.

DTC P0717 (3.6L)

The automatic transmission input speed sensor (ISS) is a permanent magnet with a coil of wire wound around it. The ISS mounts in the case cover facing the reluctor wheel of the input shaft. As the reluctor wheel is driven by the turbine shaft, an AC signal is induced in the input speed sensor. Higher vehicle speeds induce a higher frequency and voltage at the sensor.

There is a fixed air gap between the sensor and the teeth on the sensor reluctor wheel. The ISS input is used by the PCM in order to control line pressure, TCC apply and release and transmission shift patterns. This sensor is also used to calculate the gear ratios and TCC slippage.

If the PCM detects a low input speed while the vehicle and engine speeds are high, then DTC P0717 sets. DTC P0717 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0717 Input Speed Sensor Circuit Low Voltage

1. No VSS DTC P0502 or P0503.
2. The engine speed is greater than 500 RPM for 5 seconds and not in fuel cut off.
3. The vehicle speed is 8 km/h (5 mph) or more.
4. The engine torque is greater than 68 N.m (50 lb ft).

The input shaft speed is less than 100 RPM for 5 seconds.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM freezes transmission adaptive functions.
3. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
4. The PCM stores DTC P0717 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Ensure the wiring harness is not stretched too tightly or other components are pressing on the A/T inline 20-way connector body. Also inspect for proper clearance to any other components and wiring. Refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table.

1. 3: A Yes answer indicates that the transmission side of the circuit is functioning properly.
2. 4: Although the resistance is within specification in Step 3, there may be a short to ground or a short to voltage condition.
3. 8: This step begins the transmission harness diagnosis.

DTC P0717 (3.8L)

Scheme 9

The vehicle speed sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case extension and a toothed vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in the pickup coil that is proportional to vehicle speed. The transmission control module (TCM) uses this signal in order to calculate vehicle speed, shift timing and gear ratios.

If the TCM detects a low vehicle speed with a high engine speed while in a drive range, then DTC P0722 sets. DTC P0722 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0722 Output Speed Sensor Circuit Low Voltage

1. No TP sensor DTC P0121, P0122 or P0123.
2. No ISS DTC P0716 or P0717.
3. No OSS DTC P0723.
4. The engine speed is greater than 500 RPM for 5 seconds.
5. No engine torque malfunction.
6. The calc. throttle position is 8 percent or more.
7. The engine torque is greater than 50 N.m (37 lb ft).
8. The input shaft speed is 1,500-5,000 RPM.
9. The TCC slip speed is -20 RPM or more.
10. The TFT is -40°C (-40°F) or more.
11. The transmission range is not PARK or NEUTRAL.

The output shaft speed is 70 RPM or less for 4.5 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM calculates vehicle speed from input speed, engine speed and gear ratio for shift timing.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
6. The TCM stores DTC P0722 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the TCM.
2. 4: This step tests the VSS circuit for correct resistance.

DTC P0722 (3.6L)

The vehicle speed sensor (VSS) system is a pulse generator consisting of a speed sensor assembly, located in the case extension and a toothed vehicle speed sensor reluctor wheel, which is pressed onto the final drive carrier assembly. As the vehicle drives forward, the vehicle speed sensor reluctor wheel rotates. This rotation produces a variable AC signal in the pickup coil that is proportional to vehicle speed. The TCM uses this signal in order to calculate vehicle speed, shift timing and gear ratios.

If the TCM detects a large change in vehicle speed in a short period of time, then DTC P0723 sets. DTC P00723 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0723 Output Speed Sensor Circuit Intermittent

1. No ISS DTCs P0716 or P0717.
2. No 1-2 SS valve electrical DTC P0974.
3. The engine speed is greater than 500 RPM for 5 seconds.
4. The engine torque is greater than 50 N.m (37 lb ft).
5. The time since the last gear selector range change is 6 seconds or more.
6. The output speed is 350 RPM or more for 2 seconds.
7. No transmission OSS rise greater than 175 RPM for 2 seconds.
8. The change in ISS is less than 500 RPM for 2 seconds.
9. The transmission range is not PARK or NEUTRAL.

The output shaft speed drops greater than 420 RPM for 3.25 seconds.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM commands maximum line pressure.
3. The TCM freezes transmission adaptive functions.
4. The TCM calculates vehicle speed from input speed, engine speed and gear ratio for shift timing.
5. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
6. The TCM stores DTC P0723 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

The numbers below refer to the step numbers on the diagnostic table.

1. 3: This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the TCM.
2. 4: This step tests the VSS circuit for correct resistance.

DTC P0723 (3.6L)

Scheme 10

The TCM controls the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is fully applied, the engine is coupled directly to the transmission through the TCC.

The TCC used is an electronically controlled capacity clutch (ECCC). The TCM will normally allow a small amount of slip to occur with the ECCC. When the TCC is engaged, TCC slip speed is maintained at approximately 20 to 50 RPM.

If the TCM detects high torque converter slip when the TCC is commanded ON, then DTC P0741 sets. DTC P0741 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0741 Torque Converter Clutch (TCC) System - Stuck Off

1. No TP sensor DTC P0121, P0122 or P0123.
2. No ISS DTC P0716 or P0717.
3. No OSS DTC P0722 or P0723.
4. No TCC stuck ON DTC P0742.
5. No TCC release switch DTC P0842 or P0843.
6. The engine speed is greater than 500 RPM for 5 seconds.
7. The transmission fluid temperature is 20-130°C (68-266°F).
8. The calc. throttle position is between 8 and 90 percent.
9. The TCC PWM solenoid valve is commanded ON.
10. The TCC duty cycle is 65 percent or greater for 5 seconds.
11. The engine torque is 50 N.m (37 lb ft) or more.
12. The commanded gear is 2nd, 3rd or 4th.

The TCC slip speed is 175 RPM or more 6 times for 5 seconds each during the same ignition cycle.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The TCM forces the TCC OFF.
3. The TCM inhibits TCC engagement.
4. The TCM inhibits 4th gear if the transmission is in Hot Mode.
5. The TCM freezes transmission adaptive functions.
6. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
7. The TCM stores DTC P0741 in TCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

1. Prior to replacing the torque converter refer to the «Torque Converter Replacement Guide»(/buick/lacrosse/i-2004-2009/remont/automatic-trans/#how-to-diagnosis-troubleshooting-the-automatic-transaxle-4t65-e-service__torque-converter-replacement-guide) .
2. Residue or contamination may cause valves to stick intermittently.

The number below refers to the step number on the diagnostic table.

1. 3: This step verifies that the TCC engages when commanded ON by the scan tool.

DTC P0741 (3.6L)

The PCM controls the torque converter clutch pulse width modulation (TCC PWM) solenoid valve. The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is fully applied, the engine is coupled directly to the transmission through the TCC.

The TCC used is an electronically controlled capacity clutch (ECCC). The PCM will normally allow a small amount of slip to occur with the ECCC. When the TCC is engaged, TCC slip speed is maintained at approximately 20 to 50 RPM.

If the PCM detects high torque converter slip when the TCC is commanded ON, then DTC P0741 sets. DTC P0741 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0741 Torque Converter Clutch (TCC) System - Stuck Off

1. No VSS DTC P0502 or P0503.
2. No ISS DTC P0716 or P0717.
3. No TCC stuck ON DTC P0742.
4. No TCC release switch DTC P1887.
5. No TCC PWM solenoid valve DTC P2761.
6. The engine is running for greater than 5 seconds and not in fuel cut off.
7. The engine torque is greater than 28 N.m (21 lb ft).
8. The transmission fluid temperature is 20-130°C (68-266°F).
9. The TP indicated angle is 4-99 percent.
10. The IMS indicates D2, D3 or D4.
11. The TCC duty cycle is 50 percent or greater.

The TCC slip speed is 180 RPM or more for 6 seconds twice during the same ignition cycle

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM forces the TCC OFF.
3. The PCM inhibits TCC engagement.
4. The PCM inhibits 4th gear if the transmission is in Hot Mode.
5. The PCM freezes transmission adaptive functions.
6. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
7. The PCM stores DTC P0741 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

1. Prior to replacing the torque converter refer to the «Torque Converter Replacement Guide»(/buick/lacrosse/i-2004-2009/remont/automatic-trans/#how-to-diagnosis-troubleshooting-the-automatic-transaxle-4t65-e-service__torque-converter-replacement-guide) .
2. Residue or contamination may cause valves to stick intermittently.

The number below refers to the step number on the diagnostic table.

1. 3: This step verifies that the TCC engages when commanded ON by the scan tool.

DTC P0741 (3.8L)

Scheme 11

The torque converter clutch (TCC) release switch is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body.

The TCC release switch is a normally-closed switch. When the TCC is released, TCC release fluid pressure opens the TCC release switch which opens the TCC release pressure circuit. When the voltage on the circuit is high, switch open, the transmission control module (TCM) recognizes that the TCC is no longer engaged.

If the TCM detects that the TCC release switch is closed when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0742 Torque Converter Clutch (TCC) System - Stuck On

1. No TP sensor DTC P0121, P0122 or P0123.
2. No ISS DTC P0716 or P0717.
3. No OSS DTC P0722 or P0723.
4. No TCC stuck OFF DTC P0741.
5. The engine speed is greater than 500 RPM for 5 seconds.
6. The engine torque is 50 N.m (37 lb ft) or more.
7. The calc. throttle position is between 8 and 90 percent.
8. The transmission fluid temperature is 20-130°C (68-266°F).
9. The TCC is commanded OFF.
10. The vehicle speed is 16 km/h (10 mph) or greater.
11. The gear ratio is between 0.66:1 and 1.68:1.

The TCC slip speed is between -20 and 40 RPM 3 times for 6 seconds each during the same ignition cycle.

1. The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
2. The TCM commands the TCC ON at maximum capacity.
3. The TCM commands maximum line pressure.
4. The TCM commands an alternate coast shift pattern where downshifts occur at higher vehicle speeds while coasting.
5. The TCM freezes transmission adaptive functions.
6. The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Freeze Frame and Failure Records.
7. The TCM stores DTC P0742 in TCM history.

1. The ECM turns OFF the MIL after the third consecutive trip in which the TCM does not send an MIL illumination request.
2. A scan tool can clear the MIL/DTC.
3. The TCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The TCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the TCM.

1. The customer may notice an engine stalling condition.
2. If the scan tool indicated TCC release pressure was present in Step 2 and a mechanical or hydraulic condition was not found in Step 8, an intermittent short to ground condition may exist in the TCC release switch signal circuit. Refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .
3. Do not replace the torque converter for this condition, refer to «Torque Converter Replacement Guide»(/buick/lacrosse/i-2004-2009/remont/automatic-trans/#how-to-diagnosis-troubleshooting-the-automatic-transaxle-4t65-e-service__torque-converter-replacement-guide) for other concerns.
4. Residue or contamination may cause valves to stick intermittently.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: A Yes answer indicates that the TCC release switch is functioning properly.
2. 4: With the 20-way connector disconnected, the TCM should interpret the open circuit as TCC release pressure present.
3. 5: The TCC release switch is a normally closed switch and must be disconnected to properly test for a short to ground condition. An open condition in the TCC release circuit or switch would set DTC P0843. Open circuits are not diagnosed in DTC P0742.
4. 8: This step tests for a mechanical or hydraulic condition that would cause the TCC to be stuck ON.

DTC P0742 (3.6L)

Scheme 12

The torque converter clutch (TCC) release switch is part of the automatic transmission fluid pressure (TFP) manual valve position switch. The TFP manual valve position switch is mounted to the transmission valve body.

The TCC release switch is a normally-closed switch. When the TCC is released, TCC release fluid pressure opens the TCC release switch which opens the TCC release pressure circuit. When the voltage on the circuit is high, switch open, the powertrain control module (PCM) recognizes that the TCC is no longer engaged.

If the PCM detects that the TCC release switch is closed when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type B DTC.

This diagnostic procedure supports the following DTC

DTC P0742 Torque Converter Clutch (TCC) System - Stuck On

1. No TCC release switch DTC P1887.
2. No TCC PWM solenoid valve DTC P2761.
3. The engine is running for greater than 5 seconds and not in fuel cut off.
4. The engine torque is 95-270 N.m (70-200 lb ft).
5. The TP indicated angle is 5-45 percent.
6. The transmission fluid temperature is 20-130°C (68-266°F).
7. The TCC is commanded OFF.

The TCC release switch is closed, indicating the TCC is applied, 4 times for 6 seconds each, during one trip.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the conditions for setting the DTC are met.
2. The PCM commands maximum line pressure.
3. The PCM commands the TCC ON at maximum capacity.
4. The PCM freezes transmission adaptive functions.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
6. The PCM stores DTC P0742 in PCM history.

1. The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
4. The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

1. The customer may notice an engine stalling condition.
2. If the scan tool indicated TCC release pressure was present in Step 2 and a mechanical or hydraulic condition was not found in Step 8, an intermittent short to ground condition may exist in the TCC release switch signal circuit. Refer to «Testing for Intermittent Conditions and Poor Connections»(/buick/lacrosse/i-2004-2009/remont/body-electrical/#how-to-diagnosis-repair-the-wiring-systems-testing) .
3. Do not replace the torque converter for this condition, refer to «Torque Converter Replacement Guide»(/buick/lacrosse/i-2004-2009/remont/automatic-trans/#how-to-diagnosis-troubleshooting-the-automatic-transaxle-4t65-e-service__torque-converter-replacement-guide) for other concerns.
4. Residue or contamination may cause valves to stick intermittently.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: A Yes answer indicates that the TCC release switch is functioning properly.
2. 4: With the 20-way connector disconnected, the PCM should interpret the open circuit as TCC release pressure present.
3. 5: The TCC release switch is a normally closed switch and must be disconnected to properly test for a short to ground condition. An open condition in the TCC release circuit or switch would set DTC P1887. Open circuits are not diagnosed in DTC P0742.
4. 8: This step tests for a mechanical or hydraulic condition that would cause the TCC to be stuck ON.

DTC P0742 (3.8L)

Scheme 13

The pressure control (PC) solenoid valve is located in the valve body. The PC solenoid valve controls transmission line pressure based on current flow through its windings. The powertrain control module (PCM) determines desired line pressure based on throttle position and other inputs. The PCM then varies the duty cycle on the high side of the PC solenoid valve to control current flow to the solenoid. Current is controlled from about 0.02 amps for maximum line pressure to 1.1 amps for minimum line pressure. The PCM monitors the actual current to the solenoid.

If the PCM detects a commanded current draw that differs from the actual current draw by more than a calibrated value, then DTC P0748 sets. DTC P0748 is a type C DTC.

This diagnostic procedure supports the following DTC

DTC P0748 Pressure Control (PC) Solenoid Control Circuit

1. The PC solenoid valve is enabled.
2. The system voltage is: Greater than 11 volts at a low transmission fluid temperature of -40°C (-40°F). Greater than 13 volts at a high transmission fluid temperature of 151°C (304°F).

DTC P0748 sets when the duty cycle is outside the range of 0.5-95 percent for 0.2 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM enters PC solenoid valve diagnostic retest mode. The retest mode conducts the following diagnostic routine: The PCM de-energizes the PC solenoid valve, resulting in maximum line pressure. After being de-energized for 2 seconds, the PCM commands the PC solenoid valve ON at 0.1 amp for the retest period of 5 seconds. If no circuit faults are detected during the 5 second retest period, then the PC solenoid valve is returned to normal operation and DTC P0748 diagnostic is passed. If a circuit fault is detected during the 5 second retest period, then the PCM de-energizes the PC solenoid valve for 2 seconds before reentering the retest mode. If a circuit fault is detected 5 times in retest mode without returning to normal operation, then the PC solenoid valve is de-energized for the remainder of that ignition cycle. If a circuit fault is detected 3 times during normal operation, then the PCM de-energizes the PC solenoid valve for the remainder of that ignition cycle.
3. The PCM freezes transmission adaptive functions.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0748 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 2: This step verifies that the fault is present.
2. 3: This step tests the transmission wiring harness and the PC solenoid valve for correct resistance.
3. 9: This step begins diagnosis of the engine side of the circuit.

DTC P0748 (3.8L)

See also:
• Diagnostic System Check - Vehicle
• Transmission Fluid Checking Procedure
• Line Pressure Check Procedure
• Incorrect Line Pressure
• Oil Filter and Seal Replacement
• Automatic Transmission Oil Cooler Flushing and Flow Test (J35944-A)
• Engine Overheating (LY7)
• Diagnostic Trouble Code (DTC) List - Vehicle
• Testing for Intermittent Conditions and Poor Connections
• Circuit Testing
• Wiring Repairs
• Testing for Short to Ground
• Testing for Continuity
• FRONT DIFFERENTIAL CARRIER END PLAY CHECK (FW
• Control Module References
• Battery Inspection/Test
• Charging System Test
• Measuring Voltage
• Special Tools
• Automatic Transmission Inline 20-Way Connector End View (3.6L)
• Testing for a Short to Voltage
• Torque Converter Replacement Guide
• TORQUE CONVERTER ASSEMBLY REMOVAL
• Torque Converter Diagnosis Procedure