TCC not engaging

Circuit Description
The torque converter clutch (TCC) pulse width modulation (PWM) solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the TCC application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through the ignition 0 voltage circuit. The powertrain control module (PCM) controls the solenoid by providing a ground path on the TCC PWM solenoid valve control circuit. Current flows through the solenoid coil according to the duty cycle, percentage of ON and OFF time. The TCC PWM solenoid valve provides a smooth engagement of the TCC by operating during a duty cycle percent of ON time.
When the PCM detects a continuous open, short to ground, or short to power in the TCC PWM solenoid valve circuit, then DTC P2761 sets. DTC P2761 is a type B DTC.

P1740 Torque Converter Clutch or Overdrive Solenoid ...

https://www.engine-codes.com > p1740

Faulty Torque Converter Clutch (TCC) and Overdrive (OD) Solenoid. ... Torque Converter Clutch (TCC) and Overdrive (OD) clutch are tested when the Powertrain Control Module (PCM) requests TCC engagement in 3rd gear and Overdrive. The P1740 code will set if expected RPM drop is not

The powertrain control module (PCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with the TCC engaged, the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +50 RPM.
When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P0894 sets. DTC P0894 is a type B DTC.

TCC - torque converter clutch
Diagnostic Aids
• Bronze material found in the transmission oil pan may indicate stator shaft bushing wear. If bushing wear is suspected, inspect the stator shaft and the input, turbine, shaft for damage.
• Refer to Symptoms - Automatic Transmission for more information.
Do you have a scan tool ?

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.
Record the DTC Freeze Frame and Failure Records.
Clear the DTC.
Important: It may be necessary to allow multiple TCC cycles to occur in order to verify a slipping condition. It may also be necessary to ensure the transmission is warm before performing this step.
Drive the vehicle in 4th gear with the TCC commanded ON.
Does the scan tool TCC Slip Speed measure within the specified range for 7 seconds?
130-800 RPM

Inspect the torque converter clutch (TCC) solenoid valve for the following conditions:
• Internal malfunction, such as sediment or damage
• Damaged seals
• Refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness .
Inspect the torque converter clutch pulse width modulation (TCC PWM) solenoid valve for the following conditions:
• Internal malfunction, such as sediment or damage
• Damaged seals
• Refer to Torque Converter Clutch Pulse Width Modulation Solenoid, Torque Converter Clutch Solenoid, and Wiring Harness .
Did you find and correct the condition?

DTC P0894 Transmission Component Slipping
DTC P0894Circuit Description with 4L80-E / 4L85-E Automatic Transmission The powertrain control module monitors the engine speed and the transmission output shaft speed. The PCM calculates turbine shaft speed and torque converter clutch (TCC) slip speed by using inputs from the automatic transmission input shaft speed sensor, automatic transmission output shaft speed sensor, and other transmission components. The forward clutch housing is used as the AT ISS rotor. Whenever the TCC is engaged, engine speed and turbine speed will closely match, indicating low TCC slip speed. In D3, with the TCC engaged, calculated transmission component slip can only occur in the torque converter. In D4 OVERDRIVE, with the TCC engaged, transmission component slip can occur in the TCC or the fourth clutch assembly. If the PCM detects an excessive TCC slip speed in D4 OVERDRIVE, when the TCC should be engaged, then DTC P0894 sets. DTC P0894 is a type C DTC. For California emissions vehicles, DTC P0894 is a type B DTC.DTC Descriptor This diagnostic procedure supports the following DTC: DTC No MAF sensor DTC P0101, P0102 or P0103. No MAP sensor DTC P0106, P0107 or P0108. No TP sensor DTC P0120 or P0220. No VSS DTC P0502 or P0503. No ISS DTC P0716 or P0717. No TCC Stuck Off DTC P0741. No TCC Stuck On DTC P0742. No 1-2 SS valve DTC P0751, P0752 or P0753. No 2-3 SS valve DTC P0756, P0757 or P0758. No TFP manual valve position switch DTC P1810. No TCC PWM solenoid valve DTC P2761. The throttle angle is 10-100 percent. Engine speed is 1,250-5,000 RPM. The TFT is Vehicle speed is TFP manual valve position switch indicates D4. The TCC is commanded ON for 0.04 second or greater. TCC is locked ON for greater than 0.1 second. Commanded The PCM detects slip in the torque converter clutch and/or the fourth gear clutch pack with the TCC in an apply or locked mode. DTC P0894 sets during the second consecutive trip when one of the following conditions occur: The TCC slip speed is 100-550 for 10 seconds for three occurrences.The TCC slip speed is 100-550 for 10 seconds, the PCM commands maximum line pressure. The TCC slip speed is 100-550 for 12.5 seconds, the PCM commands the TCC Off for 2 seconds. The TCC slip speed is 100-550 for 15 sec For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated. The PCM commands maximum line pressure. The PCM inhibits the TCC engagement. The PCM freezes transmission adaptive functions. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal. The PCM stores the DTC P0894 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes. A scan tool can clear the MIL/DTC. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring. For Federal emissions, 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. A TFP manual valve position switch malfunction can set DTC P0894. A mechanical failure of the shift solenoids or TCC PWM solenoid valve can set DTC P0894. Internal transmission failures can result in a DTC P0894. Sticking or contaminated shift valves may cause intermittent slipping in D4. DTC P0894 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. The numbers below refer to the step numbers on the diagnostic table. 3. This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch can set a DTC P0894. 4. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present. 5. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear. 6. This step tests for a sticking TCC shift valve. 7. This step tests for proper transmission line pressure.

The problem is " The Torque Converter Clutch, (TCC) solenoid" is what actually causes the TCC to engage and disengage. When the TCC solenoid receives a signal from the ECM, it opens a passage in the valve body and hydraulic fluid applies the TCC. When the ECM signal stops, the solenoid closes the valve and pressure is vented causing the TCC to disengage. If the TCC fails to disengage when the vehicle comes to a stop, the engine will stall. This is a common problem with older GM vehicles.

P0741 "Torque Converter Clutch Solenoid stuck off"
If the PCM detects high torque converter slip when the TCC is commanded ON, then DTC P0741 sets. The Powertrain Control Module (PCM) controls the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) Pulse Width Modulation (PWM). The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is applied, the engine is coupled directly to the transmission through the TCC. The TCC slip speed should be near 0.
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P0741 "Torque Converter Clutch Solenoid stuck off"
If the PCM detects high torque converter slip when the TCC is commanded ON, then DTC P0741 sets. The Powertrain Control Module (PCM) controls the Torque Converter Clutch Solenoid Valve (TCC Sol. Valve) Pulse Width Modulation (PWM). The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is applied, the engine is coupled directly to the transmission through the TCC. The TCC slip speed should be near 0.
Thank you for using Fixya and good luck

"The PCM controls the torque converter clutch (TCC) solenoid valve pulse width modulation (PWM). The solenoid controls the hydraulic fluid for TCC apply and release. When the TCC is applied, the engine is coupled directly to the transmission through the TCC. The TCC slip speed should be near 0.

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.

Conditions for Running the DTC
• No TP DTCs P0121, P0122 or P0123.

• No VSS DTCs P0502 or P0503.

• No AT ISS DTCs P0716 or P0717.

• No TCC stuck ON DTC P0742.

• No IMS DTCs P1820, P1822, P1823 or P1825.

• No TCC PWM solenoid valve DTC P1860.

• The engine run time is greater than 5 seconds.

• The time since the gear select lever change is greater than 6 seconds.

• The IMS indicates D2, D3 or D4.

• The transmission gear ratio indicates 2nd, 3rd or 4th gear.

• The transmission fluid temperature is 20-133°C (68-271°F).

• The TP angle is 10-50 percent.

• The engine torque is 43-215 N·m (32-159 lb ft).

• The TCC solenoid valve is commanded ON.

Conditions for Setting the DTC
TCC slip speed exceeds its limit for a given torque for 5 seconds.

Refer to Torque Converter Clutch Slip Speed .

Action Taken When the DTC Sets
• The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.

• The PCM inhibits 4th gear if the transmission is in hot mode.

• 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.

• The PCM stores DTC P0741 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
• The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.

• A scan tool can clear the MIL/DTC.

• The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.

• The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

I would think it is neither,
Your problem is the torque convertor clutch solenoid is not working,You need to have a shop check and replace the solenoid in the valve body of the transmission.

Her is the definition and a list of possiable causes.


Code P1740-Torque converter clutch did not lock up when the PCM sent the command. Enabling conditions: No engine or transmissions codes are present, vehicle speed was under 70 MPH, TPS was under 33% open. When the PCM commanded the torque converter to lock, no change was detected in engine speed. Blocking action: This code can block the following monitors: none.
Testing: Check torque converter solenoid for proper operation.
P1740 TCC O/D SOL PERFORMANCE (GAS)
Theory of Operation
The Torque Converter Clutch (TCC) Solenoid is used to engage the TCC which improves fuel economy.
When Monitored
The Torque Convertor Clutch (TCC) and Overdrive Clutch (OD) will be tested each time the PCM requests TCC engagement in 3rd gear and OD.
Set Condition
The DTC will set if the expected RPM drop is not achieved while attempting to engage TCC or OD. This indicates a malfunctioning torque convertor or overdrive clutch.
Possible Causes
* ENGINE DTCS PRESENT
* TRANSMISSION DTCS PRESENT
* TRANSMISSION TEMPERATURE TOO COLD
* OIL PAN CONTAINS EXCESSIVE DEBRIS
* 3-4 SHIFT SOLENOID
* SHAFT OR SEAL DAMAGE
* TCC SOLENOID
* TORQUE CONVERTER