Chapter 12 Electronic Control Systems 301 Copyright by Goodheart-Willcox Co., Inc. Third Gear Hydraulic Flow – D Range, Converter clutch released Reverse clutch Inter clutch Forward clutch Direct clutch Manual low relief 1XX 1XX BB B2 B9 L34 K PRNDL D OD D L DL B1 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 OFF (N.O.) Sol. #2 OFF (N.O.) Sol. #3 ON (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 12-44. Overdrive range, third gear. Again, note which solenoids are energized and de-energized. (Ford) The overdrive section has no control over the governor and throttle valves. The governor and throttle valves could move the 2-3 shift valve and shift the transmission into sec- ond while the overdrive unit is engaged. To prevent this, the same pressure that moved the 3-4 shift valve also acts on the 3-4 timing valve, moving it against spring pressure. The 3-4 timing valve sends oil pressure to the upshift side of the 2-3 shift valve. This extra pressure keeps the 2-3 shift valve from moving to the downshift position as long as overdrive is engaged. The 3-4 shuttle valve is used to vary the firmness of the up and downshifts of the overdrive clutch, based on the pressure supplied to it by the governor valve. More governor pressure means a higher speed and results in a firmer apply. Low governor pressure is the result of lower speeds and causes a softer apply. DCX L4S L24 L234 L12 Rev L3 L4 CT CL