Symptoms

- Engine Light ON (or Service Engine Soon Warning Light) - Transmission will not shift gears.

Possible Causes

- Low transmission fluid level - Dirty transmission fluid - Faulty shift solenoid D valve - Shift solenoid D valve harness or connectors - Shift solenoid D valve circuit is open or shorted

When Detected

The P0766 code is detected when the ECM has detected a mechanical fault with the solenoid energized, valve stuck off

Description

Shift solenoid valve D is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.