'94 tranny quirk, control solenoid?

[FixedImage]

Good day, folks.

I recently acquired a '94 metro 3-cyl (AT) from my father-in-law. Before he brought the vehicle by, he informed us of a little quirk with it.

Essentially, it has a tendancy to randomly down- and up-shift until you're cruising at a speed of 40 mph or so. Some days... no problems at all. Other days, it's doing this constantly. It's starting to wear on me... an no doubt, on the engine as well.

Now, they've already replaced the transmission in an attempt to correct this problem, but it persists. I did a little parts research, and wonder if I need a new Transmission Control Solenoid:

http://www.rockauto.com/catalog/cata...&parttype=8476

Has anyone else experienced a similar problem, or know someone who has? Do you think this might do the trick?

[hot_sd]

There are 2 shift solenoids and they are both inside the transmission. So if the transmision was replaced most likely the solenoids are not the original (unless the new transmission came without the solenpids and old ones were put in). My guess is that it is a fault with the TCM or the wiring to the transmission. I believe the 94 has a separate TCM unlike the newer cars where the TCM is integrated into the ECM.

[mpGEO]

Your Throttle Position Sensor (TPS) can cause flaky automatic transmission problems. The best way I know to test the TPS is with an old voltmeter with a needle (analog). The output of the TPS should read as smooth needle swings with no jerks. Or maybe even better to swap it with one from a car that shifts right.

Automatic transmissions really need to be tested by the flowchart found in manuals like the factory shop manual or an ATSG manual. You can waste a lot of time and money swapping parts.