General Description

DESCRIPTION

The automatic transmission is a combination of a 3-element torque converter and triple-shaft electronically controlled automatic transmission which provides 4 speeds forward and 1 speed reverse. The entire unit is positioned in line with the engine.

Torque Converter, Gears, and Clutches
The torque converter consists of a pump, turbine, and stator, assembled in single unit. The torque converter is connected to the engine crankshaft so they turn together as a unit as the engine turns. Around the outside of the torque converter is a ring gear which 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 three parallel shafts: the mainshaft, the countershaft, and the sub-shaft. The mainshaft is in-line with the engine crankshaft.
The mainshaft includes the 1st, and 2nd/4th clutches, and gear for 3rd, 2nd, 4th, reverse, and 1st. (3rd gear is integral with the mainshaft, while reverse gear is integral with the 4th gear.)
The countershaft includes the 3rd clutch and gears for 3rd, 2nd, 4th, reverse, 1st, and parking. Reverse and 4th gears can be locked to the countershaft at its center providing 4th gear or reverse, depending on which way the selector is moved.
The sub-shaft includes the 1st-hold clutch and gears for 1st and 4th.
The gears on the mainshaft are in constant mesh with those on the countershaft and sub-shaft. When certain combinations of gears in the transmission are engaged by clutches, power in transmitted from the mainshaft to the countershaft via the sub-shaft to provide [D4], [D2], [2], [1] and [R].

Electronic Control
The electronic control system consists of the Transmission Control Module (TCM), sensors, and four solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions.
The TCM is located below the dashboard, behind the left side kick panel on the driver's side.

Hydraulic Control
The valve bodies include the main valve body, the secondary valve body, the regulator valve body, the servo body, and the lock-up valve body, through the respective separator plates. They 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 Clutch Pressure Control (CPC) valve, the 4th exhaust valve, the relief valve, and the ATF pump gears.
The secondary valve body contains the 4-3 kick-down valve, the 3-2 kick-down valve, the 2-3 orifice control valve, the 3-4 shift valve, the orifice control valve, the modulator valve, and the servo control valve.
The regulator valve body contains the pressure regulator valve, the lock-up control valve, the torque converter check valve, and the cooler check valve.
The servo body contains the servo valve, which is integrated with shift fork shaft, the throttle valve B, and the accumulators.
The lock-up valve body contains the lock-up shift valve and the lock-up timing B valve, and is bolted to the regulator valve body.
Fluid from the regulator passes through the manual valve to the various control valves.

Shift Control Mechanism
Input to the TCM from various sensors located throughout the car determines which shift control solenoid valve should be activated. Activating a shift control solenoid valve changes modulator pressure, causing a shift valve to move. This pressurizes a line to one of the clutches, engaging that clutch and its corresponding gear.

Lock-up Mechanism
In [D4] position, in 2nd, 3rd and 4th, and [D3] position in 3rd, pressurized fluid can be drained from the back of the torque converter 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 TCM optimizes the timing of the lock-up mechanism.
The lock-up valves control the range of lock-up according to lock-up control solenoid valves A and B, and throttle valve B. When lock-up control solenoid valves A and B activate, modulator pressure changes. Lock-up control solenoid valves A and B are mounted on the torque converter housing, and are controlled by the TCM.

Gear Selection
The shift lever has seven positions; [P] PARK, [R] REVERSE, [N] NEUTRAL, [D4] 1st through 4th ranges, [D3] 1st through 3rd ranges, [2] 2nd gear and [1] 1st gear.





Starting is possible only in [P] and [N] positions through use of a slide-type, neutral-safety switch.

Automatic Transaxle (A/T) Gear Position Indicator
Automatic Transaxle (A/T) gear position indicator in the instrument panel shows what gear has been selected without having look down at the console.