transmission trouble code po756 on 2000 Isuzu Trooper

trans. will not downshift into first gear. I must manually shift it and as soon as the vehicle begins to move i can put it in drive and all other gears work properly up or down. I cannot identify shift solenoid B in the trans. There are so many solenoids. po756 is vague at best.

Asked by for the 2000 Isuzu Trooper