16-11-2021
12 min.
4504

P0744 Torque Converter Clutch Circuit Intermittent

The P0744 trouble code is an OBD-II diagnostic trouble code related to the Torque Converter Clutch (TCC) control circuit in an automatic transmission.

P0744 – Torque Converter Clutch Circuit Intermittent

This code means that the Transmission Control Module (TCM) has detected an intermittent electrical or operational problem in the torque converter clutch control system.

The torque converter clutch is responsible for mechanically connecting the engine and transmission under certain driving conditions. When the clutch engages, it reduces the normal slip inside the torque converter and improves fuel economy and cruising efficiency.

With P0744, the system may work correctly at one moment and then lose the expected electrical signal or clutch operation at another moment.

What Is the Torque Converter Clutch?

An automatic transmission normally uses a torque converter between the engine and transmission.

At low speeds and during acceleration, the torque converter allows controlled slip. This makes starting and shifting smoother.

At cruising speeds, the transmission can engage the Torque Converter Clutch (TCC).

The TCC creates a more direct mechanical connection between the engine and transmission.

The simplified system is:

TCM → TCC Solenoid → Hydraulic Pressure → Torque Converter Clutch → Engine / Transmission Mechanical Connection

When the TCC is commanded ON, the clutch should engage smoothly.

When the TCC is commanded OFF, it should release.

P0744 occurs when the TCM detects that this system is not behaving consistently.

What Does "Intermittent" Mean?

The word intermittent is particularly important in P0744.

It means the problem is not continuously present.

For example:

The TCC may engage normally sometimes.
The TCC may fail to engage on another drive.
The electrical signal may disappear temporarily.
A damaged wire may make contact over bumps and then lose contact.
A connector may work when cold but fail when hot.
A solenoid may stick only at certain temperatures.
TCC slip may become abnormal only under specific driving conditions.

This can make P0744 more difficult to diagnose than a continuously present fault.

Symptoms of P0744

Possible symptoms include:

Check Engine Light
Transmission warning light
Engine RPM fluctuations
RPM increases during cruising
TCC fails to lock
TCC engages and disengages repeatedly
Shudder during TCC engagement
Harsh TCC engagement
Poor fuel economy
Transmission overheating
Reduced highway fuel economy
Limp mode
Abnormal transmission shifting
Engine stalling in some cases

Some vehicles may store P0744 without producing an obvious drivability problem.

What Does P0744 Feel Like While Driving?

RPM fluctuation at cruising speed

When the TCC should be locked, engine RPM may rise and fall unexpectedly.

For example, while maintaining a steady speed, the tachometer may repeatedly move up and down even though throttle input remains relatively constant.

TCC shudder

The vehicle may feel as though it is driving over small rumble strips when the clutch attempts to engage.

Repeated lock/unlock

The TCC may engage and release repeatedly.

Poor fuel economy

If the clutch cannot remain locked during cruising, additional converter slip can increase engine RPM and fuel consumption.

Delayed or harsh engagement

A malfunctioning TCC system can cause the clutch to engage too aggressively or at the wrong time.

Engine stalling

In certain transmission designs, a TCC that remains engaged when the vehicle is coming to a stop can cause the engine to stall.

Common Causes of P0744

Damaged TCC wiring

A broken or damaged wire can cause an intermittent loss of the control signal.

Loose transmission connector

A loose connection can interrupt the TCC circuit.

Corroded connector terminals

Corrosion can increase electrical resistance and cause intermittent operation.

Damaged internal transmission harness

The fault may be located inside the transmission.

Failing TCC solenoid

The solenoid may intermittently fail to respond to TCM commands.

Sticking TCC solenoid

Contaminated transmission fluid can cause the solenoid to stick.

Contaminated transmission fluid

Debris or clutch material can interfere with TCC hydraulic operation.

Low transmission-fluid level

Insufficient fluid can affect hydraulic pressure.

Incorrect transmission fluid

Incorrect fluid characteristics can affect TCC engagement and clutch operation.

Worn torque converter clutch

The internal clutch lining can become worn and unable to maintain the required lockup.

Valve-body problem

A sticking or worn valve can interfere with TCC hydraulic pressure.

Hydraulic pressure problem

Incorrect pressure can prevent stable TCC engagement.

TCM problem

A control-module fault can cause an intermittent command problem.

Is P0744 Serious?

P0744 should not be ignored.

The seriousness depends on the actual cause and symptoms.

An intermittent electrical connection may be relatively straightforward to repair.

However, if the problem is caused by:

TCC clutch wear
Excessive converter slip
Valve-body wear
Contaminated fluid
Hydraulic pressure problems

continued driving can result in additional transmission damage.

If the vehicle is experiencing severe shudder, overheating, repeated slipping or stalling, the problem should be diagnosed promptly.

Can You Drive With P0744?

It may be possible to drive a short distance if the transmission operates normally and the only symptom is the warning light.

However, prolonged driving is not recommended until the cause is identified.

Avoid continued driving if you experience:

Severe TCC shudder
Transmission slipping
Engine stalling
Violent engagement
Transmission overheating
Burnt transmission-fluid smell
Loss of gears
Limp mode

An intermittent problem can become a permanent failure.

P0744 vs. P0743

P0743 – Torque Converter Clutch Circuit Electrical

This code indicates an electrical problem in the TCC circuit.

P0744 – Torque Converter Clutch Circuit Intermittent

This code indicates that the TCC circuit or operation becomes abnormal intermittently.

An intermittent wiring problem can therefore be an important suspect with P0744.

P0744 vs. P0742

P0742 – Torque Converter Clutch Circuit Stuck On

The TCC is detected as remaining engaged when it should release.

P0744 – Torque Converter Clutch Circuit Intermittent

The TCC problem occurs intermittently rather than remaining continuously stuck ON.

P0744 vs. P0741

P0741 – Torque Converter Clutch Circuit Performance or Stuck Off

The TCC does not provide the expected lockup performance or is detected as stuck OFF.

P0744 – Torque Converter Clutch Circuit Intermittent

The TCC circuit or operation is inconsistent.

P0744 vs. P0740

P0740 – Torque Converter Clutch Circuit Malfunction

General TCC circuit malfunction.

P0744 – Torque Converter Clutch Circuit Intermittent

The malfunction occurs intermittently.

How to Diagnose P0744

Because the fault is intermittent, diagnosis should focus on both electrical continuity and actual TCC operation.

1. Scan the TCM

Retrieve all stored transmission codes.

Check:

Current codes
Pending codes
History codes
Freeze-frame data
TCC command
TCC slip speed
Transmission temperature
Engine RPM
Vehicle speed
Gear selection

Other transmission codes can provide important clues.

2. Check the freeze-frame data

Determine exactly when P0744 was stored.

Pay attention to:

Vehicle speed
Engine RPM
Transmission temperature
Engine load
Throttle position
Selected gear
TCC commanded state
TCC slip RPM

If the code consistently occurs at highway speeds or after the transmission reaches operating temperature, that information can be very useful.

3. Check transmission-fluid level

Follow the manufacturer's procedure.

Some transmissions require the fluid to be checked at a specific temperature.

4. Inspect the transmission fluid

Look for:

Burnt smell
Dark or severely degraded fluid
Metal particles
Clutch material
Excessive contamination

Fluid condition can provide clues about internal transmission wear.

5. Inspect the external transmission connector

Look for:

Corrosion
Loose terminals
Bent pins
Water intrusion
Fluid contamination
Damaged connector locks

An intermittent connector problem can easily cause P0744.

6. Inspect the wiring harness

Pay particular attention to areas where the harness can move or rub.

Look for:

Broken wires
Chafing
Pinched wires
Melted insulation
Poor previous repairs
Wires stretched near connectors

7. Perform a wiggle test

With appropriate diagnostic monitoring equipment connected, carefully move the transmission harness and connectors.

If the TCC signal changes or the fault appears/disappears, the wiring or connector becomes a strong suspect.

8. Check TCC solenoid resistance

Measure the solenoid according to the manufacturer's specifications.

An open or shorted coil can indicate a solenoid problem.

However, a normal resistance measurement does not prove that the solenoid works correctly under operating conditions.

9. Check the TCC solenoid command

Use a scan tool to monitor whether the TCM is commanding the TCC ON or OFF.

Compare the command with actual TCC behavior.

10. Monitor TCC slip speed

This is one of the most useful parameters for diagnosing TCC operation.

When the clutch is commanded ON, slip speed should normally decrease significantly.

If the TCM commands lockup but slip remains excessive, investigate the TCC solenoid, hydraulic system or torque converter.

11. Monitor the TCC during a road test

Observe the system while driving under conditions where the TCC normally engages.

Monitor:

TCC command
Engine RPM
Turbine/input speed
Output speed
TCC slip
Transmission temperature

An intermittent problem may only appear under certain conditions.

12. Check the TCC control circuit

Test the circuit for:

Open circuits
Short circuits
Excessive resistance
Poor grounds
Intermittent connections

13. Check voltage drop

A circuit can pass a basic continuity test but still have excessive resistance under load.

Voltage-drop testing can reveal these problems.

14. Inspect the internal transmission harness

If the external wiring is good, the internal transmission harness may need inspection.

15. Inspect the valve body

A sticking valve or worn valve bore can interfere with TCC hydraulic pressure.

16. Test hydraulic pressure

Where specified by the manufacturer, measure the appropriate hydraulic pressure.

Incorrect pressure can prevent stable TCC engagement.

17. Evaluate the torque converter

If the electrical and hydraulic systems are functioning correctly but TCC slip remains excessive, the torque converter clutch itself may be worn.

Can a Bad TCC Solenoid Cause P0744?

Yes.

A solenoid that intermittently sticks or loses electrical continuity can cause P0744.

Can Wiring Cause P0744?

Yes.

Wiring is one of the important possibilities because the code specifically describes an intermittent condition.

A broken conductor inside the insulation can sometimes make contact normally and then open when the harness moves.

Can a Bad Connector Cause P0744?

Yes.

Loose or corroded terminals can cause intermittent TCC operation.

Can Dirty Transmission Fluid Cause P0744?

Yes.

Contaminated fluid can interfere with solenoid and valve-body operation.

Can Low Transmission Fluid Cause P0744?

Yes, potentially.

Low fluid can cause hydraulic instability and interfere with proper TCC operation.

Can a Bad Torque Converter Cause P0744?

Yes.

A worn internal TCC clutch may fail to maintain the required lockup.

However, the torque converter should not be blamed before the electrical and hydraulic systems have been tested.

Can a Bad Valve Body Cause P0744?

Yes.

A sticking valve or excessive valve-body wear can cause unstable TCC hydraulic pressure.

Can a Bad TCM Cause P0744?

Yes, although it is less common.

The TCM should only be considered after the wiring, solenoid and hydraulic system have been properly tested.

Can P0744 Cause Transmission Shudder?

Yes.

TCC shudder is one of the most recognizable symptoms of a torque-converter clutch problem.

Can P0744 Cause RPM Fluctuation?

Yes.

If the TCC repeatedly engages and disengages, engine RPM can fluctuate noticeably during steady-speed driving.

Can P0744 Cause Poor Fuel Economy?

Yes.

If the TCC cannot maintain lockup, additional torque-converter slip can increase engine RPM and fuel consumption.

Can P0744 Cause Engine Stalling?

Yes, in certain situations.

If the TCC remains engaged as the vehicle comes to a stop, the engine can be forced to slow excessively and may stall.

Can P0744 Cause Transmission Overheating?

Yes.

Excessive torque-converter slip generates heat.

Can P0744 Damage the Transmission?

Yes, if the underlying problem is ignored.

Continued excessive converter slip can increase:

Transmission temperature
Fluid degradation
Clutch wear
Torque converter wear
Internal transmission stress

Common Diagnostic Mistakes With P0744

Replacing the torque converter immediately

An intermittent electrical problem can produce P0744 without the torque converter being defective.

Replacing the TCC solenoid without testing the wiring

A damaged harness or connector can produce the same symptom.

Checking only resistance

The solenoid may have normal resistance while sticking mechanically.

Ignoring TCC slip data

TCC slip RPM is extremely useful for determining whether the clutch actually locks.

Ignoring transmission-fluid condition

Contaminated fluid can cause TCC solenoid and valve-body problems.

Assuming every P0744 causes obvious symptoms

An intermittent fault may initially produce only occasional RPM fluctuations.

Replacing the TCM too early

The control module should be considered only after the circuit and components have been verified.

What Is the Correct Repair for P0744?

The repair depends on the confirmed cause.

Possible repairs include:

Repairing damaged TCC wiring
Replacing damaged connector terminals
Repairing loose connections
Cleaning connector corrosion
Repairing water intrusion
Repairing the internal transmission harness
Replacing the TCC solenoid
Servicing the valve body
Cleaning contaminated hydraulic passages
Correcting transmission-fluid level
Replacing incorrect or severely contaminated fluid
Repairing hydraulic-pressure problems
Replacing a worn torque converter
Repairing internal transmission components
Updating TCM software where applicable
Reprogramming the TCM
Replacing the TCM if its failure is confirmed

How to Test the Vehicle After Repair

After completing the repair, the TCC system should be monitored during a road test.

Verify that:

TCC commands are stable
TCC engagement occurs at the expected time
TCC slip decreases appropriately after lockup
Engine RPM remains stable during cruising
There is no repeated lock/unlock condition
No shudder occurs
Transmission temperature remains normal
Gear changes are normal
No warning lights return
No additional transmission codes appear
P0744 does not return

The test should include different speeds, throttle positions and transmission temperatures because an intermittent fault may not appear immediately.

Frequently Asked Questions About P0744

What does P0744 mean?

P0744 means the transmission control system has detected an intermittent problem in the Torque Converter Clutch circuit or its operation.

Does P0744 mean the torque converter is bad?

No. The problem may be caused by wiring, a connector, TCC solenoid, valve body, transmission fluid, hydraulic pressure or the torque converter itself.

Can a bad TCC solenoid cause P0744?

Yes.

Can a wiring problem cause P0744?

Yes.

Can a bad connector cause P0744?

Yes.

Can dirty transmission fluid cause P0744?

Yes.

Can low transmission fluid cause P0744?

Yes, potentially.

Can a bad torque converter cause P0744?

Yes, but it should be diagnosed after the electrical and hydraulic systems have been checked.

Can P0744 cause shudder?

Yes.

Can P0744 cause RPM fluctuation?

Yes.

Can P0744 cause poor fuel economy?

Yes.

Can P0744 cause overheating?

Yes.

Can P0744 cause stalling?

It can, particularly if the TCC fails to release as the vehicle stops.

Can I drive with P0744?

A short trip may be possible if the transmission operates normally, but prolonged driving should be avoided until the intermittent fault is diagnosed.

Does P0744 mean the transmission needs to be replaced?

No. The cause may be an electrical connection, wiring problem, TCC solenoid or valve-body issue rather than a failed transmission.

Final Thoughts on P0744

P0744 – Torque Converter Clutch Circuit Intermittent indicates that the TCM has detected an inconsistent problem with the torque converter clutch control circuit or TCC operation.

The word "intermittent" is the key to this code. The fault may disappear during normal testing and return only when the vehicle reaches a particular temperature, speed, load or vibration condition.

A logical diagnostic sequence is:

Scan Tool → Freeze-Frame → Fluid → Connector → Wiring → Wiggle Test → TCC Solenoid → TCM Command → TCC Slip Data → Hydraulic Pressure → Valve Body → Torque Converter → TCM

Do not immediately replace the torque converter.

An intermittent wire, connector or TCC solenoid can produce P0744, while a worn torque converter clutch or valve-body problem can also create the same code.

The most useful diagnostic information is often the relationship between TCC command and actual TCC slip. If the TCM commands the clutch to lock but slip remains high, the technician can then determine whether the problem is electrical, hydraulic or mechanical.