P0740 · Torque Converter Clutch Circuit Malfunction

Key facts

Definition and circuit logic

• Torque Converter Clutch Circuit Malfunction

First-fault record

• Preserve rpm, load, speed, temperature, system voltage and relevant commanded/actual values from the first event.

Diagnostics and measurement

Symptoms

• Evaluate the symptom and companion codes from the same event as P0740.

Freeze frame and initial capture

• Preserve rpm, load, speed, temperature, system voltage and relevant commanded/actual values from the first event.

Common diagnostic mistakes

• Do not treat the code label as a definitive failed-part diagnosis; compare command, feedback and physical measurement.

Post-repair verification

• After repair, safely reproduce the original fault condition and recheck DTC status.

Safety

• Use manufacturer service information for application-specific procedures and exact thresholds.

Possible causes

• Sensor/solenoid circuit, fluid level/temperature, hydraulic pressure, clutch/valve-body or TCM communication/calibration fault.

Live data to monitor

• Input/output speeds, commanded/actual ratio, fluid temperature, selected gear and solenoid/clutch commands.

Measurement sequence for a DTC

1. Record which module stored the code and under what conditions.
2. Review freeze-frame and simultaneous codes together.
3. Verify power, ground and voltage-drop basics.
4. Compare commanded and actual values in live data.
5. Recreate the operating condition after repair.