Shift Solenoids SSA and SSB
WARNING: This page is about a different car, the 2003 Ford RV Cutaway, 2003 Ford Econoline, 2003 Ford E550 Super Duty, 2003 Ford E450 Super Duty, and 2003 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.