No reverse, when the engine is warmed up. 96 Saturn SL

Hello,
My Service Engine Soon light has come on and my reverse isn't working, when
the engine is warmed up. It goes into reverse when it's cold, which it starts
out, here in Michigan, but it seems to shift hard in drive and once the engine
warms up, I pretty much need a pull-through to park in.
Has anyone else had a similar problem, and if so, what caused it? I don't
have access to whatever computer can diagnose why the Service Engine Soon light
is on, and I'd like to get this thing fixed soon. There's plenty of Automatic
Transmission Fluid, and it doesn't smell burnt.
I was thinking maybe the thermostat might be bad, and not opening at all,
thus heating up the coolant in the engine, but not cooling it through the
cooling system. Could that cause this? Or am I way off?
I'd appreciate any help you folks might be able to offer. Thanks,
Tedrick

 

Sounds like upper valve body. If you know your way around the greasy side
and aren't afraid of the transmission part is about $250 otherwise about
$500 for the repair.
Larry

 

Not good news, but thanks for the input.
Tedrick

 

Could be worse. It's not a serious repair.
Larry

 

IMHO and limited experience, the first thing to do when you have almost any
kind of malfunction in an auto trans is to CHANGE the FLUID and change and
EXAMINE the FILTER. This is especially true if the malfunction is
intermittent or seems to be temperature related. Make sure you are using
the correct fluid. Cut the filter apart and wash the paper element in
solvent in a CLEAN can, then pan the solvent looking for particles. If you
find particles, save them and take them to a shop for advice. A magnifying
glass and magnet will help. The particles could be steel, brass, copper,
aluminum or rubber and can give you some indication of what is failing. It
is seldom possible to get a complete drain of the torque converter so if
this procedure helps it should be repeated after the old and new fluid has
had a good chance to mix.

Few people change the ATF often enough, there is not much oil and is
inexpensive maintenance. Worn ATF gives little indication of its condition
visually and has to be really bad before it will smell. After draining you
can often see a metallic sheen on the drained oil from the suspended metal
particles, if you have a filter this may not be visible.

Saturn also uses ATF in the manual transmissions and in all differentials.
They used to recommend an initial change at something like 10,000 mi and
repeat changes regularly. The initial change always demonstrates the
metallic sheen from the metal worn off during break-in. I believe they are
no longer suggesting regular changes which is something I do not agree with
but makes them look better to the eco-police. The transmission is an
expensive component and is hard to service, oil is cheap and all machinery
likes clean oil.

If this does not solve your problem it will do no harm and is cheaper than
anything else you can try. This has solved problems for me in every kind of
auto trans including heavy equipment where other repair options can cost
tens of thousands.

Happy trails.

 

I had the same problem. They rebuilt the upper throttle body of the
transmissions. this is a regular problem of that year. I was told .

 

"VALVE" body.