Chapter 12 Electronic Control Systems 303 Copyright by Goodheart-Willcox Co., Inc. Screen Rear clutch Rear servo Front clutch Front servo Accumulator Overdrive clutch 3-4 accumulator 3-4 shuttle valve 3-4 timing valve 3-4 shift valve Overdrv sol Lockup sol Lockup valve Lockup timing valve Selector lever in drive direct drive T/C unlocked Front clutch lubrication L/U switch valve Cooler To lubrication Torque converter Oil filter Pump Screen Regulator valve Manual valve 1-2 shift valve Governor plug Throttle plug Throttle plug Limit valve Governor plug 2-3 shift valve Governor valve Oil pressures Line 57-94 PSI Governor 0-57 PSI Converter/lube 5-57 PSI Throttle 0-94 PSI 1-2 Shift control 25-70 PSI Pump suction Throttle valve Kickdown valve 1-2 shift control valve Shuttle valve 7 9 4 3 6 8 1 2 5 Figure 12-46. Third gear of a transmission with partial electronic shift control. The transmission has shifted hydraulically through first, second, and third gears. Study the position of the solenoids and shift valves. (Chrysler) output commands from the ECM and moves the variable ratio control valve. Moving the control valve varies hydrau- lic pressure to the drive pulley piston. Note that the piston moves one pulley side. Fluid pressure, called primary feed oil, moves from the variable ratio control valve through a calibrated orifice to the drive pulley piston. The calibrated orifice restricts oil flow to prevent overly rapid movement of the pulley in the inward direction. When fluid pressure is reduced, the check ball unseats and allows the primary feed oil to exhaust rapidly. When the drive pulley moves, force is transmitted through the metal belt to overcome hydraulic pressure in the driven pulley piston. The drive pulley piston has a greater surface area than the driven pulley piston, and will always force the driven pulley to respond to size changes in the drive pulley. Line pressure is fed to the driven pulley piston to match pulley clamping force to engine output. The primary limit valve is a pressure regulator valve that keeps excessive pressure from damaging the drive pul- ley piston and other parts. Primary feed oil enters a cham- ber on the side opposite the spring. When feed oil pressure exceeds spring pressure, the valve moves toward the spring side, opening an exhaust passage. Manual Shifting Programs A manual shift program is a method of manually changing gears on electronically controlled transmissions and transaxles. The manual shift program allows the driver to change between gear ratios by moving the shift lever, Figure 12-49. The transmission’s electronic control module performs the actual gear changes based on shift lever move- ment, while continuing to monitor engine and vehicle sen- sor inputs. The transmission/transaxle unit itself is identical to one without a manual shift program. Moving the shift lever to a special position switches the control module to the manual shift program. See Figure 12-50. Once the manual shift program is activated, the shift lever is momentarily pushed up (the + direction in Figure 12-50) to shift the transmission or transaxle to the next higher gear. Momentarily pushing the shift lever down (the – direction in Figure 12-50) shifts to the next lower gear. On some manual shift programs, the shift lever is moved to the left or right to change gears. Notice that in addition to the manual shift program (M program), the shift lever in Figure 12-50 has a provision for fully automatic shifts (XE program). It also has a provision for