300 Automatic Transmissions and Transaxles Copyright by Goodheart-Willcox Co., Inc. Second Gear Hydraulic Flow – D, D Range Reverse clutch Inter clutch Forward clutch Direct clutch Manual low relief 1XX 1XX BB B2 B9 L34 K PRNDL D OD D L B1 DL Pump Manual Pump Filter Sump P HH Conv. reg. sol. reg. Pump UU BB AA TT L234 KK Bypass cl sol VFS TV sol. P1 L34XX 1XX Q BBB P2 2-3 shift OD D L P2 DCX L234 B6 LISR T B10 SF P1 Sol. #1 ON (N.O.) Sol. #2 ON (N.O.) Sol. #3 OFF (N.O.) P3 P2 DD Rear B3 Rel. Apply L/I servo OD D L 2-3 servo reg. GG Engagement LISA P2′ Pull-in 3-2 shift timing DCX L Pump Fwd. clutch control P3 LFC 3-4 shift J OD D L Int. clutch shuttle R ICEX P2′ 1-2 shift M L L3 L234 L34XX FC Rev L4 Rev L 12 L LL DCEX P2 PP LISR LI2X L234 L12 L Rev L12 B5 DL B F B11 L34XX ICEX L12 S E L12X TV VFS L L4 Pressure failsafe Backout E V (opt) Accum. reg U ZZ FF MM Pump NN (opt) LFC C Int. cl L234 VV Y CC PC Main reg. TV Rev CPY L Z Bypass clutch control C-BY 1-2 cap mod. 12 acc. L4 B4 H O.D. servo N-D accum. X L12X 3-4 accum. ODSA 1-2 accum. Converter C-BY CT CI W F. lube Cooler Converter drain back YY Diff. = Line = Pump control = TV = Converter feed, case lube = Accumulator charge A Rev Figure 12-43. Overdrive range, second gear. Note which solenoids are energized and de-energized. Compare this with first gear. (Ford) through the check ball as long as the overdrive solenoid is de-energized. There is not enough pressure to move the 3-4 shift valve against spring pressure. When the vehicle reaches a certain speed, the ECM will decide that a shift to overdrive is desirable, and it will ener- gize the overdrive solenoid. When the overdrive solenoid is energized, the check ball seals the exhaust passage. Oil pressure can no longer leak through the check ball. Pressure rises and moves the 3-4 shift valve against spring pressure. This action sends line oil pressure to the overdrive clutch and shifts the transmission into fourth gear. Some oil is also diverted to the 3-4 accumulator to cushion the shift. See Figure 12-47. DCX L4S L24 L234 L12 Rev L3 L4 CT CL