P0766 – Shift Solenoid ‘D’ Performance or Stuck Off

P0766 Possible Symptoms

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

P0766 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

P0766 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.