P0740: An open converter-clutch circuit is separate from a slipping converter

P0740 is the torque-converter clutch open-circuit classification in Ford's cited tables. It concerns the electrical control path. A converter that does not achieve lockup may produce a related functional result, but that observation does not by itself reproduce the open-circuit evidence behind this code.

The controller compares command and feedback

Ford describes the electrical test as a disagreement between output-driver feedback and the commanded state for a typical 1.5 seconds. The operation summary also gives a broader five-second electrical monitoring duration. These are distinct descriptions of the monitor and should not be presented as one universal stopwatch test.

Electrical monitoring runs continuously, while mechanical converter-clutch monitoring is associated with lockup operation. The table separates P0740 from the functionally stuck-off and stuck-on categories. An apparently good or bad slip value belongs to that functional evidence stream, not a direct proof of circuit continuity.

Keep the full failure classification

The architecture tables show P0740_13 for an open circuit, while ground and power shorts use other failure types and displayed codes. Capture the module identity and suffix before following a generic scanner label.

Useful verification aligns commanded clutch state, driver-feedback status and current fault status under the applicable electrical procedure. The document does not identify whether an interruption is in the load, harness or driver, nor provide a universal resistance value. A converter replacement cannot be justified solely by the existence of this electrical code.

Source and applicability

Ford 2024–2025 gasoline OBD operation summary, July 16 2024 revision; only the cited monitor and transmission architectures. No individual vehicle fitment or universal calibration is inferred. Ford PDF, page 153. Ford PDF, page 155.