Engine start stop applications for solenoid pumps

A solenoid pump and associated hydraulic circuitry are intended for use in automatic transmissions capable of engine start stop (ESS) operation. In a first embodiment, a solenoid pump provides pressurized hydraulic fluid to respective inputs of two way check valves. The other inputs are provided with controlled hydraulic fluid from a transmission valve body. The outputs of the check valves are provided to those hydraulically operated torque transmitting devices associated with first gear. The solenoid pump is activated when the transmission is in gear and the engine is stopped to maintain hydraulic pressure in those actuators associated with first gear. A second embodiment provides hydraulic fluid to actuators associated with reverse. A third embodiment includes a solenoid pump and latching solenoid valve both communicating with a hydraulic supply In a fourth embodiment, a solenoid pump provides hydraulic fluid to the exhaust backfill circuits of hydraulic operators in an automatic transmission.