Description & Operation

Automatic transaxle is electronically controlled with 4 forward speeds and one reverse. Transaxle consists of clutches, mainshaft, countershaft, shift control solenoid valves, lock-up control solenoid valves, linear solenoid and lock-up torque converter. Transaxle has a differential assembly bolted to the transaxle. Power is delivered from transaxle to the differential assembly by the extension shaft. See Fig 1.

Lower valve body assembly consists of main valve body, secondary valve body, throttle valve body, linear solenoid, shift control solenoid valves and oil passage body. Lower valve body is bolted to transaxle housing. Other valve bodies used are regulator valve body, oil pump body and accumulator body. These valve bodies are bolted to torque converter housing.

Transaxle shifting and torque converter lock-up are controlled by the Powertrain Control Module (PCM). PCM is located under carpet on passenger's side foot well. Transaxle shifting is related to engine torque through the linear solenoid used to operate the throttle valve. The PCM controls the linear solenoid located on the throttle valve body. The PCM determines appropriate shift point and activates proper shift control solenoid valve for transaxle shifting.

When shift lever is moved, manual valve on main valve body is moved by the shift cable. Shift lever also changes position of A/T gear position switch mounted on the shift lever. The A/T gear position switch delivers an input signal to the PCM to indicate shift lever position. The PCM uses this input signal to control shift control solenoid valves. The PCM determines appropriate shift point and activates proper shift control solenoid valve for transaxle shifting.

When in "D4", 2nd, 3rd and 4th gears, torque converter lock-up exists and transaxle mainshaft rotates at same speed as engine crankshaft. Under certain conditions, torque converter lock-up clutch is applied during deceleration in 3rd and 4th gears. Torque converter lock-up is controlled by the PCM. The PCM receives various input signals and operates lock-up control solenoid valves. Operation of lock-up control solenoid valves controls the modulator pressure.

The PCM contains a self-diagnostic system, which stores a fault code if failure or problem exists in transaxle electronic control system. Fault code can be retrieved to determine transaxle problem area. For information on electronic transaxle components, see M5DA DIAGNOSIS article.

Transaxle is equipped with shift and key interlock systems. Shift interlock system prevents shift lever from being moved from "P" position unless brake pedal is depressed and accelerator pedal is in idle position. In case of a malfunction, shift lever can be released by placing ignition key in release slot near shift lever. Key interlock system prevents ignition key from being removed from ignition switch unless shift lever is in "P" position. For additional information on shift and key interlock systems, see SHIFT INTERLOCK SYSTEMS - 3.5RL article.

The A/T gear position indicator on instrument panel contains lights to indicate which position A/T gear position switch on shift lever is in. For information and testing of A/T gear position indicator, see M5DA DIAGNOSIS article.

When transaxle gear combinations are engaged by clutches, power is transmitted from mainshaft to countershaft to provide different gears.