P0766: Solenoid D failed-off behavior is judged through eligible response events

P0766 describes shift solenoid D as functionally failed off. The Ford monitor is assessing whether a requested control transition produces the expected result. That assessment differs from detecting an electrical break in the D circuit.

A normal later response does not erase the event history

The typical functional filter gains three counts for a bad event and loses one for a correct non-shifting clutch state. Nine counts store the result. Because successful and unsuccessful events carry different weights, one good observation cannot explain the entire path to a stored code.

Ford also distinguishes an approximately one-second shifting observation from a 2.5-second non-shifting event. Interpreting a capture requires the operating phase and the command history, not simply the time that elapsed after the code was cleared.

Use the specific D-channel category

The architecture table pairs P0766 with P0765_7F. Its open-circuit cell uses P097D/P0765_13, while P0767/_7E is the opposite functional state category. Preserve these differences when an aftermarket description collapses them into the same component name.

A meaningful verification record includes the intended transition, observed response and electrical diagnostic status. The source does not identify a particular friction element or establish that a valve is physically seized. It supports choosing the functional diagnostic branch; the exact transmission's evidence must then identify why the expected state was not reached.

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 151. Ford PDF, page 152. Ford PDF, page 155.