The automatic transaxle allows engine torque and power to be transmitted to the front wheels within a narrow range of engine operating speeds. It will allow the engine to turn fast enough to produce plenty of power and torque at very low speeds, while keeping it at a sensible rpm at high vehicle speeds (and it does this job without driver assistance). The transaxle uses a light fluid as the medium for the transmission of power. This fluid also works in the operation of various hydraulic control circuits and as a lubricant. Because the transaxle fluid performs all of these functions, trouble within the unit can easily travel from one part to another. For this reason, and because of the complexity and unusual operating principles of the transaxle, a very sound understanding of the basic principles of operation will simplify troubleshooting.
The AXOD (automatic transaxle overdrive) is used with 3.8L engine. Beginning in 1991 some vehicles were equipped with the AXOD-E transaxle which is basically the same as the AXOD with the addition of electronic transaxle controls. Beginning in 1993, some vehicles came equipped with the AX4S (automatic transaxle four-speed) or AX4N (automatic transaxle four-speed non-synchronized) transaxle. The AX4S was formerly the AXOD and is the same as the AXOD-E. In addition, the AX4N which is also very similar, but is non-synchronized, hence the N in the name.
The AXOD, AXOD-E, AX4S, and AX4N automatic transaxles are 4-speed units. They all have two planetary gear sets and a combination planetary/differential gear set. Four multiple plate clutches, two band assemblies, and two one-way clutches act together for proper operation of the planetary gear sets.
A lock-up torque converter couples to the engine crankshaft and transmits engine power to the gear train by means of a drive link assembly (chain) that connects the drive and the driven sprockets. The application of the converter clutch is controlled through an electronic control integrated in the on-board EEC-IV system computer. These controls, along with the hydraulic controls in the valve body, operate a piston plate clutch in the torque converter to provide improved fuel economy by eliminating converter slip when applied.
The AXOD-E uses a turbine speed sensor in conjunction with a vehicle electronic control system. These components send operational signals to the EEC-IV microprocessor.