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Description The automatic transmission is a combination of a 3-element torque converter and a dual-shaft electronically controlled Torque Converter, Gears and Clutches meshes with the starter pinion when the engine is being started. The entire torque converter assembly serves as a flywheel while transmitting power to the transmission mainshaft. The transmission has two parallel shafts: the mainshaft and the countershaft. The mainshaft is in line with the engine crankshaft. The mainshaft includes the 1st, 4th and 2nd clutches and gears for 4th, 1st, 2nd and reverse (3rd gear is integral with the mainshaft). The countershaft includes the 3rd, 1st-hold and reverse clutches, and gears for 3rd, 4th, 1st, 2nd, reverse and park. The secondary drive gear is integrated with the countershaft. The gears on the mainshaft are in constant Electronic Control The electronic control system consists of a Powertrain Control Module (PCM), sensors, a A/T clutch pressure control solenoid and four solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions. Hydraulic Control The lower valve body assembly includes the main valve body, the secondary valve body, the throttle valve body, the ing. Other valve bodies, the regulator valve body, the ATF pump body and the accumulator body, are bolted to the torque converter housing. The main valve body contains the manual valve, the 1-2 shift valve, the 2-3 shift valve, the 3-4 shift valve, the 4-3 kick-down Fluid from the regulator passes through the manual valve to the various control valves. The ATF pump body contains the The 1st, 1st-hold, 2nd and reverse clutches receive fluid from their respective feed pipes, and the 3rd and 4th clutches receive fluid from the internal hydraulic circuit. Shift Control Mechanism Input from various sensors located throughout the vehicle determines which shift solenoid valve the PCM will activate. Activating a shift solenoid valve changes modulator pressure, causing a shift valve to move. This pressurizes a line to one of the clutches, engaging the clutch and its corresponding gear. Lock-up Mechanism In position, in 2nd, 3rd, and 4th, and position in 3rd, pressurized fluid is drained from the back of the torque con- verter through a fluid passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the PCM opti- clutch (lock-up control) solenoid valves A and B, and throttle valve. When torque converter clutch (lock-up control) Main Menu Table of Contents Main Menu Table of Contents |