I am humbly suggesting that the information in the Technical Manual for the washer pump connections is in error. This morning, I hooked up the pump to test hoses into/out of a bucket of water, and most definitely the nipple labeled "B" is the supply water into the pump, and the nipple labeled "D" is the pressurized output to the nozzle. Reversed, it does not work. This is consistent with what Al stated that "D" stands for pressure. In addition, the pressure nipple is "barbed" consistent with pressure fittings, and the input nipple is smooth, consistent with suction fittings.
Thanks, Jim