Another 95 SL1 automatic problem

[jndalton]

My daughter's 95 SL1 starting slamming into gear for a second time. About 22 months ago (18000 miles), she took it to two different Saturn dealerships and they eventually replaced the valve body assembly, both the input and output shaft nuts, the upper engine mount, the pressure control solenoid, and of course replaced the fluid along the way. Now, when it's cold it usually slams very roughly into Drive, Reverse, Park, Nuetral when sitting still and the parking break on. Sometimes it doesn't do this, however. After everything warms up, this goes away, but it still sometimes pauses when upshifting, allowing the engine revs to shoot up, and resulting in a slam into gear.

She took it to the dealer who did most of the work listed above and they said they THINK the bus plate needs to be resoldered. She then took it to Aamco and they said it needed a new PCM. Because of the symptoms, I have my doubts about both of these solutions, primarily since it doesn't happen all the time. I have replaced the fluid and added some treatment to it and checked the three fuses related to the transmission. It still does the slam when cold, but the upshifting problem seems better. I pulled the battery cable, but I have only driven it a few miles. What do you guys think? Do I need to give it more time to relearn the shifting or should I be looking at something else?

[rkuris]

My advice: do a transmission pressure test. Apparently, the temperature sensor can be removed and a 300psi pressure gauge installed to test the pressure. You want the pressure when you're in park, the pressure in drive, and then the pressure with the TLP fuse pulled, and compare it to spec.

[rkuris]

Steps that I plan on trying tomorrow:

(1) warm transmission: drive it 5 miles or so, then park the car.
(2) remove the battery and battery tray. Try do to this quickly so that the transaxle will not cool too much.
(3) remove the temperature sensor, mounted just above the filter, from the case.
(4) Attach a 300lb or more pressure gauge to the port.
(5) Attach the battery so you can start the car
(6) Start the car and put it in park. pressure should be 58-72 psi.
(7) Remove the TLP fuse. Pressure should jump to 218-245 psi.
(8) apply parking brake, shift into drive. Pressure should be more than 175 psi.

Note that you may set some transmission error codes from this procedure, which can be safely ignored.

[ssicarman]

You can access the trans pressure test port without removing the battery. You just need to remove the air filter boxes.

[rkuris]

Oooh, thank you!

[jndalton]

Thanks.
I'll give that a try and let you know what I come up with.