'99 Saturn SL2 automatic tranny upshifting like crap

Greetings,

It's been a long time since I've posted here ... haven't had any
problems with our '99 Saturn SL2 ... until now.

Car: '99 Saturn SL2, automatic, 125k highway miles

Symptom: Hard shifting from 1-2, 2-3, 3-4. Used to happen when car was
hot. Now it's happening even when the car is not warmed up yet.
Initially I thought it was an overfilled transmission since I had just
serviced it at around 120k miles with brand new transmission fluid and
filter, but doing another drain and refill didn't make any difference.
The shift points of the transmission are where they should be under both
light, medium, and hard acceleration; it's just when it does the actual
shifting when the car really "slams" into the next gear. Downshifts are
ok, shifting from Park - Reverse, Reverse - Drive, Drive - Reverse has
no delays, but just a little bit harsher than normal.

Suspected: Based on what I've read through this newsgroup, there's
three possible culprit.

a.) Bad battery. Bad battery causing voltage irregularities to the ECM,
causing it to shift bad. It seems a lot of people have had experience
with the battery going bad. We bought the car new, and have never
replaced the battery. I live in Southern California, and the A/C is
being used regularly with the hot weather we're having. With a
voltmeter, battery measures 12.5V with engine off, and about 14.1V with
engine on and with or without the headlights on. (Please note: my '98
Taurus SHO has a far lower battery voltage reading at around 13.8V with
the engine running ... suspect that original battery is going bad, but
that's another story ...)

b.) Alternator. So many articles about the alternator being bad which,
again, can cause voltage irregularities to the ECM, causing it to shift
bad. But again, see voltage readings on battery above when the engine
is running. I don't hear any abnormal noises eminatting from the
alternator to indicate bad bearings, and the serpentine belt was
replaced about 30k miles ago. I haven't taken it off yet to get it
checked out.

c.) Actual transmission problem, probably electrical. I found a
less-than-month old article on this newsgroup where the gentleman
mentioned his '99 had problems shifting, which Saturn diagnosed to be a
bad transmission solenoid and bus plate ... both accessible from the
outside, and it seemed to fix his vehicle's problem.

The charging light is not turning on on the instrument panel.

Any clues as to what you think might be the part at fault based on your
personal experience?

-Alan

----------------
'99 Saturn SL2, 125k miles
'98 Ford Taurus SHO, 80k miles
'94 Ford Taurus GL, 104k miles
'89 Nissan Maxima, 243k miles
'77 Mercury Colony Park S/W, 150k miles
'85 Honda Accord, 120k miles (when sold)
'83 Honda Civic, 349k miles (when sold)

 

As a followup: a replacement alternator and battery did not do the
trick. So we ended up taking it to the dealer (Saturn of Santa Clarita,
CA). Car was taken in at 1:30pm. Got a phone call around 2:30pm saying
that they found the hard shifting problem was caused by a faulty main
pressure line solenoid located near the tranny's valve body. Got
another call at 5pm saying the car was done (<!>Two hours!<!>). Picked
up car the next day since I was 40 miles away at work. Total cost: $30
parts plus 2-1/2 hour labor cost = $212 with a free car wash and
interior cleaning by the dealership. The tranny now shifted normally
like it should.

I did learn one thing though from my experimentation with the alternator
and battery: when the time comes for me to replace the alternator, I now
know how to do it.

Oh, and I did return the battery and alternator for a refund and kept
the original battery and alternator in service.

Regards,

-Alan

----------------
'99 Saturn SL2, 125k miles
'98 Ford Taurus SHO, 80k miles
'94 Ford Taurus GL, 104k miles
'89 Nissan Maxima, 243k miles
'77 Mercury Colony Park S/W, 150k miles
'85 Honda Accord, 120k miles (when sold)
'83 Honda Civic, 349k miles (when sold)

 

Not bad. If only all tranny problems were that easy and cheap