Transmission

P0744 — Torque Converter Clutch Circuit Intermittent

Severity: medium Drive with care, to a shop

What P0744 means

The engine or transmission control module operates a torque converter clutch (TCC) solenoid that locks the converter at cruising speed to eliminate slip. P0744 means the electrical circuit of that solenoid is behaving erratically, with the signal dropping out and returning. Because the fault comes and goes, the code may clear itself and then reappear.

Symptoms

  • Intermittent shudder at steady cruise
  • Jerks when the converter locks or unlocks
  • Worse fuel economy
  • Check Engine light on
  • Random other transmission codes
  • Transmission overheating under load

Possible causes

  1. Intermittent failure of the TCC solenoid winding
  2. Loose or corroded transmission connector
  3. Wire fatigue in the internal transmission harness
  4. Chafed or damaged wiring to the solenoid
  5. Signal wire shorted to ground or power
  6. Faulty PCM or TCM (uncommon)

How to diagnose

  1. Read all codes and freeze-frame data and note when the fault sets
  2. Check transmission fluid level and condition
  3. Inspect the transmission connector for corrosion, moisture and loose pins
  4. Wiggle the harness with the engine running while watching scan tool data
  5. Measure the solenoid resistance and compare it with the manufacturer spec
  6. Test the wiring to the module for opens and shorts
  7. Command the solenoid with a scan tool and verify its response
  8. Suspect the module only after everything else checks out

Common fixes

  • Clean or replace the connector and damaged terminals
  • Repair or replace the damaged wiring
  • Replace the TCC solenoid
  • Replace the internal transmission harness
  • Change the fluid if it is contaminated
  • Replace or reprogram the PCM/TCM if confirmed faulty

Questions and answers

What does P0744 mean?

It means the torque converter clutch solenoid circuit is intermittently faulty. The control signal is unstable, so the converter does not always lock correctly.

Can I drive with P0744?

Briefly and carefully, yes, but don't put it off. Slipping and shudder heat the fluid and wear the transmission.

Why does the code come and go?

Usually a poor connection or a partly broken wire that acts up with vibration or heat. The code will keep returning until the defect is fixed.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.