What is the most likely cause of a DCV shifting normally with overrides but not with electric power?

When a direction control valve (DCV) shifts normally with overrides but fails to do so under electric power, the most likely cause is an open solenoid. The solenoid is responsible for converting electrical energy into mechanical movement to operate the valve. If the solenoid is not receiving power due to an open circuit, it will not activate, preventing the valve from shifting as required.

In the scenario described, the ability to shift the valve manually through overrides indicates that the mechanical components are functioning correctly. This reinforces the notion that the issue lies with the electrical aspects of the system, particularly the solenoid, which is designed specifically to operate the valve when energized.

Other potential issues, such as a faulty actuator or worn valve seals, would likely exhibit symptoms regardless of whether electrical power is applied, as they would affect the mechanical operation consistently. An incorrectly set power supply might suggest inadequate voltage or current, but the test indicates that the valve operates with manual overrides, which points more directly to a problem with the solenoid itself. Therefore, an open solenoid stands out as the most plausible explanation for the valve's behavior.