Shift Solenoids SSA and SSB
WARNING: This page is about a different car, the 2002 Ford RV Cutaway, 2002 Ford Econoline, 2002 Ford E550 Super Duty, 2002 Ford E450 Super Duty, and 2002 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
Shift solenoids SSA and SSB provide gear selection of first through fourth gears by controlling the pressure to the three shift valves.