P0743: Torque Converter Clutch Circuit Electrical

What it means

An electrical fault in the torque converter clutch solenoid circuit — open, shorted, or out-of-range driver current. The transmission usually inhibits TCC apply when this code is active.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The torque converter clutch (TCC) solenoid controls whether the converter clutch can lock the engine to the transmission input during suitable driving conditions. The transmission module monitors the TCC solenoid’s electrical circuit and sets P0743 when its current or circuit behavior indicates an electrical fault such as an open or short. It may disable lockup while the fault is active.

Common causes

Most likely first.

1. TCC solenoid electrically failed
2. Wiring/connector fault

Symptoms

• Check engine or transmission warning light on
• Torque converter lockup may be unavailable

How to diagnose it

1. Use a scan tool to record freeze-frame data and check TCC command and related transmission codes to see when the electrical fault occurred.
2. Inspect the TCC solenoid connector and transmission harness for loose pins, corrosion, fluid intrusion, chafing, or damaged insulation.
3. With the circuit safely disconnected as specified by the manufacturer, check TCC solenoid coil continuity and compare it with the manufacturer's specification.
4. Check the TCC circuit wiring for opens or shorts to ground or supply, following the vehicle wiring diagram.
5. If the solenoid and wiring pass, verify the transmission module’s TCC driver circuit using the manufacturer's diagnostic procedure.

Common fixes

• Clean and secure a loose or corroded TCC solenoid connector.
• Repair damaged wiring or connector terminals in the TCC circuit.
• Replace the failed TCC solenoid if its coil test is out of specification.
• Repair the transmission module driver circuit if testing confirms it is faulty.

Can I keep driving?

If the vehicle shifts normally, a short trip to a repair location may be possible, but avoid towing, steep climbs, and prolonged highway driving because converter lockup may be unavailable. Stop driving if the transmission slips, overheats, or shifts abnormally.