Description & Operation: Introduction
Transaxles are electronically controlled 4-speed automatics. Transaxles consists of 3 sets of multi-plate clutches, 2 sets of multi-plate brakes, a one-way clutch set, 2 planetary gear sets, and a 3-element, 1-step, 2-phase torque converter with a built-in clutch. Planetary gears are made up of a sun gear, carrier, pinion gear and annulus gear. See Fig 1 .
The "INVECS-II" electronic control system incorporates feedback and learning controls to provide smooth shifting throughout all shift ranges. Gear shifting clutches use hydraulic balancing mechanisms to enable gear shifting at high engine speeds. Transaxle shifting and torque converter lock-up are controlled by Powertrain Control Module (PCM), located behind right side of instrument panel. See Figure . PCM contains a self-diagnostic system, which stores Diagnostic Trouble Codes (DTC) if transaxle faults occur. DTCs can be retrieved to determine transaxle problem area.
PCM receives information from input devices and transmits electrical signals to appropriate shift control solenoid valves on valve body assembly which controls transaxle shifting. Solenoid valves included are: low-reverse solenoid valve, second solenoid valve, underdrive solenoid valve and overdrive solenoid valve. PCM controls torque converter lock-up by operating torque converter clutch control solenoid valve, also located on valve body.
These electronically controlled transaxles are equipped with adaptive shift control capabilities which allows optimal gear shifting and learning control for all types of driving and road conditions. Optimal control assures automatic selection of the best gear for any road condition. Learning control function tailors gear shift timing to driving patterns of individual drivers. This transaxle control system is referred to as INVECS-II.