No 4-3 Downshift In "D" Position

Forward clutch pressure, line pressure, valve body (3-4 shift valve, solenoid pressure regulator valve, OD servo regulator, 3-4 capacity modulator valve, 1-2 and 2-3 shift valves), incorrectly tightened valve body bolts, Shift Solenoid No. 1 (SSA) failure, OD servo, No. 2, 7, and/or 9 valve body check balls, blocked valve body solenoid screen, pump assembly, OD band and/or reverse clutch drum assembly, intermediate one-way clutch assembly, forward clutch assembly or input shaft.