P0743: Torque Converter Clutch Circuit Electrical
What to do
Expect no torque converter lock-up, so higher cruising revs and worse economy. Driveable, but the fluid runs hotter than it should while it stays unfixed.
What this code means
An electrical fault in the converter clutch solenoid circuit — an open winding, a short, or resistance outside the expected range. Unlike P0741, this is a measurable circuit fault rather than an inference about behaviour, which makes it the more straightforward of the two to diagnose: the solenoid's resistance can be measured directly and compared against specification.
One thing to check before the transmission is opened. The solenoid connector is inside the gearbox on most designs, with the harness passing through a sealed pass-through fitting in the case. Fluid can wick along the wire strands inside that fitting and corrode the joint from within, which reads as an open circuit while every visible part looks perfect. Confirming resistance at the internal connector rather than only at the module distinguishes harness from solenoid, and they are quite different jobs.
Likely causes
Start here
- Faulty torque converter clutch solenoid · moderate
- Open circuit in solenoid wiring · moderate
- Fluid tracking into the transmission connector · moderate
Less common
- Wiring shorted to ground · moderate
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P0743.