|Code||Fault Location||Probable Cause|
|P0741|| Torque converter clutch (TCC) solenoid -performance/stuck off |
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|Wiring, TCC solenoid stuck off|
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Table of Contents
- What Does Code P0741 Mean?
- What are the common causes of code P0741 ?
- What are the symptoms of code P0741 ?
- How do you troubleshoot code P0741 ?
- Codes Related to P0741
- Get Help with P0741
What Does Code P0741 Mean?
OBD II fault code P0741 is most commonly defined as “Torque Converter Clutch Circuit Performance” or sometimes as “Torque Converter Clutch- Stuck Off”, and is set when the PCM (Powertrain Control Module) detects an abnormal electrical value in the torque converter clutch control circuit. The words “Stuck Off” in a definition of this code refers to the fact that the torque converter clutch control solenoid is stuck in the “OFF” position, and can therefore not engage the torque converter clutch or lock-up mechanism.
Although the actual parameters that set code P0741 vary greatly between applications, the basic operating principles and purpose of the torque converter clutch remain the same in all cases, which is to provide a solid link between the engine and the transmission, much like a conventional clutch locks a manual transmission to the engine. By locking the transmission to the engine, all slippage in the torque converter is eliminated, which increases engine power delivery to the driving wheels, and improves fuel economy.
In terms of the system’s operation, the PCM gathers information from various sensors such the throttle position sensor, vehicle speed sensor, transmission turbine speed sensor, engine speed sensor, boost control sensor, and others to determine the degree to which the engine must be locked to the engine. The lock-up function is accomplished by solenoids that control the flow rate, and hence the usable pressure of pressurized transmission fluid to vary the amount of converter lock-up.
However, to prevent engine torque from overcoming the shear strength of the transmission fluid in the torque converter, or to prevent excessive torque from damaging transmission or other drivetrain components, the system is also designed to allow some slippage to occur under certain conditions, such as severe acceleration.
“Shear strength” refers to the transmission fluids’ ability to transmit torque from the drive, to the driven side of the torque converter; when the fluids’ shear strength is exceeded or overcome, the torque converter is said to “slip” and some of the engine power is lost to the drivetrain as a result.
The pressure required to accomplish converter lock-up derives from the transmission’s integral pressure pump that is driven by the engine via the torque converter. Based on inputs from the PCM, some of the pressure is directed through either solenoids or valve shuttles in the valve body to activate the actual torque converter lock-up mechanism.
When the PCM detects a difference between the actual amount of lock-up and the amount of lock-up it expects to see given reigning operating conditions, a code will be set. Depending on the application, a warning light may or may not be triggered, since some applications require more than one failure cycle to occur before triggering a warning light.
The image below shows a simplified schematic of a typical torque converter that incorporates a clutch/lock-up mechanism. Note the flow path the transmission fluid takes to activate the clutch.
What are the common causes of code P0741 ?
The main causes of code P0741 are degraded and/or dirty transmission fluid, and wiring issues such as short circuits, open circuits, or disconnected wires. Other possible causes could include the following-
- Use of unsuitable transmission fluid
- Low fluid level
- Insufficient hydraulic pressure
- Defective torque converter clutch solenoid
- Blockages of small fluid passages by sludge or wear particles
- Sludge or wear particles that prevent the free movement of valve shuttles in the valve body
- Mechanical failures inside the transmission
- Defective PCM or other control modules. Note that control module failures are rare events, and the fault must be sought elsewhere before any controller is replaced.
What are the symptoms of code P0741 ?
In some cases, there may be no symptoms present other than a stored trouble code and possibly an illuminated warning light. However, some symptoms involve serious drivability issues that may vary in severity between applications. Some possible symptoms could include the following-
- Excessive transmission slippage under hard acceleration
- Transmission overheating
- Harsh shifting
- Increased fuel consumption
- Depending on the application, other transmission or torque converter clutch codes may be present along with P0741
NOTE: Although it relatively rare for the torque converter clutch not to disengage when only code P0741 is present, a short circuit in the control circuit or a mechanical failure of the clutch itself could prevent the clutch from disengaging in some cases. When this happens, the most common symptom is that the engine will stall when the vehicle is brought to a stop while a gear is selected.
How do you troubleshoot code P0741 ?
WARNING: Because the torque converter clutch control solenoid is most often located inside the transmission, transmissions with lifetime fills can sometimes present a serious challenge to successfully resolving code P0741. The problem involves the fact that these transmissions usually have no provision for draining the fluid, but worse, the volume of fluid required to fill the transmission is a detail that car manufacturers choose not to share with the independent auto repair trade.
Therefore, draining the fluid out of a “filled-for-life transmission by whatever method is NOT recommended, since it is not known how much fluid is required to fill the transmission to the correct level. Moreover, since it is not known how much fluid remains behind in the transmission and torque converter after draining, there is no reliable way of telling how much fluid you’d need to fill the transmission to the correct level.
Note that over-filling a transmission is as bad as under-filling it; therefore, non-professional mechanics or mechanics that do not have access to all relevant technical information and the required equipment should NOT attempt to drain and/or refill any filled-for-life transmission.
NOTE #1: Since all automatic transmission functions depend on the quality and cleanliness of the transmission fluid, the diagnostic procedure for code P0741 must start with an inspection of the transmission fluid. In some cases, merely topping off the fluid level or replacing the fluid will resolve the problem, but be aware that replacing or topping off the fluid is not guaranteed to resolve this code.
NOTE #2: Unless transmission flushing is expressly approved by the manufacturer, the procedure must be avoided at all costs. Flushing can dislodge sludge and wear particles that can become lodged elsewhere in the transmission, where they can clog small fluid passages or prevent the free movement of valve shuttles in the valve body.
NOTE #3: Diagnosing code P0741 requires a dedicated transmission fluid pressure gauge, as well as a repair manual that includes both a wiring diagram and a complete schematic of the hydraulic circuits in the transmission.
Start the diagnostic procedure by checking the transmission fluid level, as well as the condition of the fluid. Transmission fluid that is dark in color, has a “burnt” smell, or contains large wear particles or metal flakes is indicative of a worn, dirty, clogged-up, or damaged transmission. In cases where the transmission fluid is seriously degraded, the prudent thing to do would be to refer the vehicle to obtain a professional assessment of the transmission.
NOTE: Refer to the WARNING above.
If the transmission fluid appears to be serviceable and up to the correct level, record all codes present, as well as all available freeze frame data. This information can be very useful should an intermittent fault be diagnosed later on.
At this point, it is also a good idea to check the transmission’s working pressure, since many transmission problems, which sometimes include code P0741, are the direct result of low hydraulic pressure. Consult the manual on the correct procedure to check the transmission pressure, but be aware that failure to follow the directions exactly can result in serious personal injury, and/or damage to the transmission.
Compare the obtained reading to the value specified in the manual, but take note that there are no quick or easy fixes for low transmission pressure problems, and especially if the transmission has a life-time fill. If the actual measured pressure falls within specifications, proceed with the electrical diagnosis.
If the transmission’s working pressure falls within the manufacturer’s specifications, consult the manual for the application being worked on to determine the color-coding, location, function, and routing of all wiring in the control circuit, and perform a thorough visual inspection of all wiring. Look for damaged, burnt, disconnected, shorted, or corroded wiring and/or connectors.
Do not assume that there is no damage to the wiring merely because no damage is visible. In many cases, the actual damage to the wiring or some other issue is located inside the transmission, so to determine if this is the case, disconnect the transmission harness from the PCM (to avoid damaging the controller), and perform ground, resistance, continuity, and input voltage checks on the harness at the point where the harness connects to the transmission.
Compare all obtained readings with those stated in the manual; note though that all values must conform to stated values exactly. If discrepancies are found, replace the wiring harness between the connector and the PCM with an OEM replacement to avoid possible resistance and continuity issues. Clear all codes after replacing wiring, and retest the system to see if the code returns.
NOTE: If damaged wiring is found, resist the temptation to make repairs. Repairs in this circuit often cause issues with high resistances and/or continuity, which would make replacement of the entire transmission harness the wiser option. However, replacing the transmission harness involves draining the transmission fluid: refer to the WARNING above.
It the external harness is serviceable, but the torque converter clutch control solenoid cannot be activated manually with the scanner, the problem is caused by either faults in the internal wiring or a mechanical failure of some kind that prevents movement of the solenoid shuttle.
Check the condition of the clutch control solenoid by comparing its internal resistance against the value specified by the manufacturer. However, if the solenoid is defective, the application largely determines whether it is possible to replace the solenoid on a DIY basis or not. In some cases, the control solenoid is located on the outside of the transmission, but in the majority of cases, the solenoid is attached to the valve body, which requires removing at least the oil pan from the transmission.
Filled-for-life transmissions are best referred to the authorized dealer for diagnosis and repair, but where the fluid can replaced on a DIY basis, removing the oil pan is the only way to gain access to the transmission’s internal wiring. Inspect this wiring for any signs of damage or problems that could cause short -, or open circuits. Also, perform resistance and continuity checks on the wiring, and replace all wiring with OEM replacements if any deviation from specified values is found.
Take note that the actual converter clutch solenoid forms a part of the circuit, and it must therefore be tested as well. Disconnect the solenoid from the rest of the wiring, and test it for resistance and continuity. Compare obtained readings to the values stated in the manual, and replace the solenoid if readings do not fall within the range specified by the manufacturer.
When replacing the solenoid and/or internal wiring, make absolutely sure that all wiring is secured properly by using all of the attachment points or fasteners provided. Once all wiring is installed, secured, and reconnected, clear all codes, and attempt to operate the control solenoid manually by using the scanner.
Note though that some solenoids operate silently, meaning that an audible “click” may be absent, so watch the scanner closely to see if the solenoid reacts to input signals. If the scanner confirms that the solenoid is indeed reacting correctly, continue to activate it several times to see if it fails to react on some input cycles.
If the solenoid fails to work even once, there is likely to be an intermittent fault present, which can be extremely challenging to find and repair. In some cases, it might be necessary to allow the fault to worsen before an accurate diagnosis and definitive repair can be made.
Once it is certain that the control solenoid is working properly, all internal wiring is routed correctly and secured, and that all electrical readings fall within the manufacturer’s specifications, fit a new filter to the valve body, and reinstall the transmission oil pan using a new gasket.
Consult the manual on the correct grade and type of fluid for the application, and follow the instructions provided in the manual to ensure that the transmission is filled with the correct volume of fluid. Allow the transmission to reach operating temperature by monitoring the transmission fluid temperature with the scanner, but cycle the transmission through its full range of gears (including reverse) to make sure that fluid is circulating properly. Don’t forget to check the transmission oil pan for leaks before operating the vehicle. Repair all leaks before test-driving the vehicle to prevent possible damage to the transmission.
If there are no fluid leaks present and the transmission is hot, clear all codes and operate the vehicle for at least one complete drive cycle with the scanner connected to see if the code returns. If the code does not return after a few complete drive cycles, the repair can be considered successful.
Codes Related to P0741
- P0740 – Relates to “Torque Converter Clutch Circuit Malfunction”
- P0742 – Relates to “Torque Converter Clutch Circuit Stuck On”
- P0743 – Relates to “Torque Converter Clutch Circuit Electrical”
- P0744 – Relates to “Torque Converter Clutch Circuit Intermittent”
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