[yaz4real]

The Saturn automatic transmission shifts by using electro-mechanical solenoids to pressure shifting. For the DIYer, it is difficult to determine if it is an electrical or a mechanical issue.

First to note is the transmission's maintenance. Has the ATF fluid and the filter been changed at 30 K intervals? If not, consider this tasks which is very easy to do.

In the forums, DIYers are recommended to ensure the alternator is working properly and providing the required power to the solenoids. Have the system tested at an autoparts store that provides this service for free.

On the top of your transmission under the hood and by looking in back of the battery and under the brake master cylinder is where the transmission electrical connectors are. The connector is held in by an 8 mm bolt. To disconnect, of course, disconnect your battery. When disconnecting, notice if the top of the connector and inside is clean and corrosion free. If ATF fluid is seen here, there is a problem. If any of the 10 internal connections do not look good, this may be the issue. Note that when you take this connection apart, the shifting patterns will have to be relearned.

Take a look at all the fuses in the under hood fuse box. Generally the fuses in the center are for the transmission. The cover tells you what fuses are for what.

Look down near the transmission fluid filter. Nearby is a connector and sensor that is exactly the same as the ECTS. This sensor values the ATF temperature and sends to the PCM to assist in shifting. If the connection or sensor was broken, it will likely present a check engine light. However, if the connection is poor or intermitten, it may cause some shifting issues.

Try these DIYer tasks before moving forward.