Transaxle Description

Transaxle Description





NOTE: The AX4S automatic transaxle was formerly designated AXOD. To avoid unnecessary re-tooling and to make sure of correct identification, the AX4S will retain its original AXOD METRIC main control cover.

The AX4S has two planetary gearsets and a combination planetary/differential gearset. Four multiple-plate clutches, two band assemblies and two overrunning clutches act together for correct operation of the planetary gearsets.

Identification Tags





When repairing the automatic transaxle, refer to the identification tag located on top of the converter housing.

Range Selection





The transaxle has six range positions: P, R, N, 0, D and 1.

Park
In the PARK position:
^ there is no powerflow through the transaxle.
^ the park pawl locks the final drive.
^ the engine may be started.
^ the ignition key may be removed.

Reverse
In the REVERSE position:
^ the vehicle may be operated in a rearward direction, at a reduced gear ratio.
^ engine braking will not occur.

Neutral
In the NEUTRAL position:
^ there is no powerflow through the transaxle.
^ the output shaft is not held and is free to run.
^ the engine may be started.

Overdrive
Overdrive is the normal position for most forward driving.
Overdrive provides:
^ automatic shifts.
^ apply and release of the torque converter clutch.
^ maximum fuel economy during normal operation.

Drive
This position provides all automatic shifts for 1st through 3rd gears. This position also provides apply and release of the torque converter clutch (TCC). Coast braking occurs in third gear.

Manual 1 Position
If this position is selected at normal road speeds, the transaxle will shift into second gear, then into first when the vehicle reaches a speed below approximately 45 km/h (28 mph).
This position provides:
^ first gear operation only.
^ engine braking for descending steep grades.

Shift Patterns
Upshifts
Upshifting is controlled by the powertrain control module (PCM). The PCM receives inputs from various engine or vehicle sensors and driver demands to control shift scheduling, shift feel and torque converter clutch (TCC) operation.
The PCM has an adaptive learn strategy to electronically control the transaxle, which will automatically adjust the shift feel. The first few hundred miles of operation of the transaxle may have abrupt shifting. This is a normal operation. If the battery has been disconnected for any reason it will need to be kept disconnected for approximately 20 minutes to reset the adaptive shift pressure strategy or use the scan tool to do the keep alive memory (RAM) reset.

Downshifts
Under certain conditions the transaxle will downshift automatically to a lower gear range (without moving the transaxle range selector lever). There are three categories of automatic downshifts: coastdown, torque demand, and forced or kickdown shifts.

Coastdown
The coastdown downshift occurs when the vehicle is coasting down to a stop.

Torque Demand
The torque demand downshift occurs (automatically) during part-throttle acceleration when the demand for torque is greater than the engine can provide at that gear ratio. If applied, the transaxle will disengage the TCC to provide added acceleration.

Kickdown
For maximum acceleration, the driver can force a downshift by pressing the accelerator pedal to the floor. A forced downshift into a lower gear is possible below calibrated speeds. Specifications for downshift speeds are subject to variations due to tire size, engine and transaxle calibration requirements.