Mechanics

AUTO TRANSMISSION GEAR SLAM SHIFTING, SELECTING INAPPROPRIATE GEARS

1995 Saturn SL2 • 200 miles


Scary Automatic Transmission problem.

I have a 95 Saturn SL2 twim cam with auto trans.
Here is my current problem, and I've been fighting this on and off for awhile.

I'll list the things I did to try to deal with it below. But the problem is proving to be
annoyingly persistant and I'm running out of ideas and patience.

Can somebody please help me with this?

I will drive the car down a side street, say at about 25-35 mph, and it will appear to
be avoiding 3rd gear (I think it's 3rd). The car will sometimes go into a gear where the
revs are in-appropriately too low and there is no torque available.

Much worse is what happens to me on the expressway - I will be driving up the entrance
ramp to the expressway, and the car will appear to skip over a gear, again, I think it's
3rd, and go straight into 4th from 2nd. I will have little torque climbing up the ramp,
but then I'll get up to highway speeds, and everything will appear to be alright - I'm
now in the proper gear for the proper speed of 50-65 mph speed range.

This will continue for about half a minute or so and but then. All of a sudden, it will
decide to downshift into 3rd gear (or sometimes even 2nd!) While I'm on the highway
doing better than 50 mph! The car will lug sharply backwards and the motor will start
screaming practically at redline. And nothing I can do will pop it out of that gear!

If I continue to drive it that way, it will go a few miles that way before eventually
shifting into a more appropriate gear. Otherwise, I have to pull over to the side of
the road to a complete stop before taking off again. It will then usually run through
all the proper gears on its way up to highway speed again.

In the past I had a mild reverse slam problem, which spread to some of the forward gears. I took some of the below actions to try to fix the problem, which appeared to fix some of the problems for awhile, but resulted in some others.



**** this is what I've tried in order to deal with the problem so far.

upon first notice of problem;

- changed ATF fluid & filter -- after 2 weeks, no effect

- added ATF fluid treatment -- aft 2 weeks, no effect

- found, pulled, cleaned & polished battery, chassis, transmission wiring
connectors & grounds -- aft 2 weeks, no effect

- checked & retorqued side input shaft nut & output shaft nut, neither were
loose, both at 111 ft/lbs or above. Also found no play in shafts.

- replaced valve body & gasket, retorqued installation bolts. Refilled AFT fluid.

After doing all that, and driving the car for over for 120 miles, the reverse gear
remained all but unusable. I would put the car in reverse and wait for up to 20
seconds before it would drop into gear, and then the car would bounce off the
reverse gear with a hard slam each time I used the gas. However, the problem with the forward gears seemed to be resolved.

That problem (reverse) persisted for over two months before mysteriously clearing up
completely overnight.

The car drove decently after that for awhile, but now it's back to it's old issues.
After half a year of no problems, I'm having some mildly rough shifts into reverse
again. Pretty rare (once or twice a week), but still an unwelcome development.
Been having a few rough forward shifts as well. Seems to dislike either 2nd or
third gear, not certain which. Which brings me to the problems I'm having now.

Today I pulled the old valve body out of storage (the one I'd removed last time)
and checked all the resistances on the solenoids, and they all checked out to be
4.5 Ohms, except for one, which tested as 4.3 ohms.

All the contact routes on the bus plate tested as 0.4 Ohms or below, so I'm
beginning to wonder if the valve body WAS NOT THE PROBLEM afterall.
The only thing I could see was a tiny look of darkened burn look to one of the
contacts going to the very first pin on the first solenoid (the one in the "F"
slot).

Can anyone tell me what my problem is and how to fix it?



Avatar
Saturn3
May 16, 2012.



Take to a trans guy and have him scan for codes. This can be a multiple prolem, like a cracked case, bad seals and or clutches. Or one of the sensors or pressure regulator is not working right. Terminal "F" is for one of the actuators, so this could aslos be a problem there or outside not making great contact as well as pcm not getting good contact as well but you really need to see if this thing is throwing a code. Auto parts scanners won't pick up trans codes so you need a pro type to do that.

Hmac300
May 16, 2012.
Just to add to this one you can flash the transmission codes out of this car by jumping the diagnostic link connector. It will first flash the engine codes thru the check engine light then if there are transmission codes they will flash thru the low coolant light. Also where did you get the valve body you got as a replacement?It doesnt sound like a very good one if the reverse delay for over 20 seconds after replacing it. The first thing I would check is the high low and the pressure in park reverse abd drive. Its easy to do and the gauge set is cheap the one I have is nice and under 60. Most of the time the transmission issues in the saturn S model saturns are pressure related. With the pressure being too high or too low.

Saturntech9
May 17, 2012.
I would also check for codes.

Saturntech9
May 17, 2012.