1st Gear: Powerflow
WARNING: This page is about a different car, the 2011 Ford Pickup, 2011 Ford F550 Super Duty, 2011 Ford F450 Super Duty, and 2011 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
In 1st gear, Shift Solenoid A (SSA) is commanded ON by the PCM/ TCM to apply the forward (1,2,3,4) clutch. In manual 1st gear, SSD is commanded ON by the PCM/ TCM to apply the low/reverse (1,R) clutch. In 1st gear, the forward (1,2,3,4) clutch connects the front carrier to the No. 3 sun gear. With the rear carrier held stationary by the low OWC clutch, power is transferred from the No. 3 sun gear through the rear planetary gears to the ring gear/output shaft at a 3.974 to 1 ratio. Because the One-Way Clutch (OWC) is the holding element, there is no engine braking. The low/reverse (1,R) clutch is applied in manual 1st gear to provide engine braking.