See Figure 1
There are two 4-speed automatic transaxles used in all Saturn vehicles. They are virtually the same by design and differ internally almost only by gear ratio. The two transaxles are equipped with different gears, in order to best utilize the engines to which they are mated. The MP6 transaxle is found only on vehicles with the SOHC engine, while the MP7 was available only with the DOHC engine.
If there is a question as to whether the transaxle in your vehicle is the original component, an identification code is stamped on the top of the transaxle clutch housing. The code includes information such as model year, transaxle type (MP6 or MP7), where the transaxle was built and when the unit was built. An interpretation of the entire identification code can be found under the Manual Transaxle portion of this section.
The Saturn automatic transaxle utilizes four multiple disc clutches, a four-element torque converter with a lock-up clutch, 1st gear sprag clutch and a servo actuated dog clutch. The unit is controlled by the PCM through five electro-hydraulic actuators, in order to provide shift timing, shift feel and on-board diagnosis. A POWER/NORMAL button in the center console can be used to communicate with the PCM to alter shift points for performance/economy.
The PCM is capable of performing self-diagnostic functions on the various electronic transaxle control circuits. The SHIFT TO D2 light will illuminate and remain on if certain trouble codes are present in memory. Codes and flags are extracted using the ALDL, as described in Emission Controls of this repair guide.
Beginning with the 1993 model year, the PCM transaxle controller was changed in order to produce smoother and more efficient shifts. This new controller also contained additional trouble codes and flags.