P0744

P0744 is the intermittent-fault sibling of P0743 — the TCM sees the TCC circuit electrical fault come and go, usually heat-related, and sets the code after enough fail-clear cycles inside a single drive. The diagnostic difficulty is that the fault often won't be present when the truck arrives at the shop on a cold morning, which is why P0744 has a reputation as a tech-headache code. Cheapest-first ladder: (1) Live-data the TCC commanded state and TCC slip RPM on a warm drive cycle — a healthy locked converter holds 0-50 RPM slip steady, an intermittent solenoid or worn clutch shows slip spikes >100 RPM that come and go with throttle input. (2) Heat-test the solenoid pack — pull the pan once the transmission is at 180+ F operating temp and ohm the TCC solenoid hot; a coil that reads 25 ohms cold and 50+ ohms hot is breaking down with temperature and will set intermittent codes you can't catch cold. (3) Inspect the transmission case connector and pin tension on the external harness — a partially backed-out pin causes intermittent open circuits that only appear when the transmission flexes under load. (4) Pull the transmission fluid and look at color/smell — burnt fluid (dark brown, varnish smell) means the TCC clutch is shedding friction material into the line pressure circuit, which fouls the solenoid screen and causes intermittent application even with a healthy coil. Expensive-misdiagnosis caveat: chasing a P0744 by replacing the solenoid pack on a transmission with already-burnt fluid is throwing money at a converter that's mechanically dying — pull the converter and inspect before quoting a solenoid job.

Vehicle-specific patterns: Ford 4R70W and 4R75W see P0744 from the same slow apply-circuit leak as P0743, with the intermittent flavor showing up earlier in the wear cycle before the leak gets bad enough to set hard P0743. Ford 6R80 throws intermittent P0744 from lead-frame cracking that opens and closes the TCC circuit as the transmission heat-cycles. GM 4L60E / 4L65E / 4L70E sets P0744 constantly in the 100k-150k mile window — the TCC PWM solenoid degrades gradually, and intermittent operation precedes hard failure by 5,000-15,000 miles; many shops replace the solenoid on any P0744 over 90k miles as preventive. GM 6L80 / 6L90 (2007-up Silverado, Sierra, Yukon, Escalade) commonly throws P0744 from valve body wear at the TCC regulator bore, not from the solenoid itself — a TransGo or Sonnax sleeve kit is the real fix. Chrysler 545RFE / 68RFE sees P0744 from a slow TCC apply leak at the front pump or converter hub seal. Estimated repair: $250 to $2,200.