Components
DESCRIPTIONThe Automatic Transmission is a combination of a 3-element torque converter and a 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 a single unit.
They are 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 secondary shaft. The mainshaft is in line with the engine crankshaft.
The mainshaft includes the clutches for 3rd and 4th, and gears for 3rd, 4th, Reverse and Idler (Reverse gear is integral with 4th gear).
The countershaft includes the 1st-hold clutch and gears for 2nd, 3rd, 4th, Reverse, 1st and Idler. The secondary shaft includes 1st and 2nd clutches, and gears for 2nd, 1st and Idler.
The 4th and reverse gears can be locked to the countershaft at its center, providing 4th gear or Reverse, depending on which way the selector is moved.
The gears on the mainshaft are in constant mesh with those on the countershaft and the secondary shaft. When certain combinations of gears in the transmission are engaged by the clutches, power is transmitted from the mainshaft to the countershaft (via the secondary shaft) to provide [D3], [D4], [2], [1] and [R].
ELECTRONIC CONTROL
The electronic control system consists of the Transmission Control Module (TCM), sensors, and 4 solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions.
The TCM is located below the dashboard, under the front lower panel on the passenger's side.
HYDRAULIC CONTROL
The valve assembly includes the main valve body, secondary valve body, servo valve body, regulator valve body and throttle valve body.
They are bolted to the torque converter housing as an assembly.
The main valve body contains the manual valve, 1-2 shift valve, 2-3 shift valve, cooler relief valve, lock-up shift valve, lock-up control valve, 3-2 kick-down valve, modulator valve, CPC valve and oil pump gears.
The secondary valve body includes the 4th exhaust valve, 3rd kick-down valve, 3-4 shift valve, servo control valve, servo orifice control valve and the 2nd orifice control valve.
The servo valve body contains the accumulator pistons and servo valve. The regulator valve body contains the regulator valve, torque converter check valve, and lock-up timing valve. The throttle valve body contains the throttle valve B and relief valve. Fluid from the regulator passes through the manual valve to the various control valves.
The clutches receive oil from their respective feed pipes or internal hydraulic circuit.
SHIFT CONTROL MECHANISM
Input from various sensors located throughout the car determines which shift control solenoid valve the TCM will activate. 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], in 2nd, 3rd and 4th, and [D3] in 3rd, pressurized fluid is drained from the back of the torque converter through an oil passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the main- shaft 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: PARK, REVERSE, NEUTRAL, D4 1st through 4th gear ranges, D3 1st through 3rd gear ranges, [2] 2nd gear and [1] 1st gear. Starting is possible only in P and N positions through the use of a slide-type, neutral-safety switch.
AUTOMATIC TRANSAXLE (A/T) GEAR POSITION INDICATOR
The A/T gear position indicator in the instrument panel shows which gear has been selected without having to look down at the console.