I can't help on the Blazer, but I know Chrysler electronically controlled
transmissions will default to second gear if they encounter a sensor
reporting a problem in what they call "limp home" mode. In most cases, with
the Chrysler transmissions, this is most often caused by one of the speed
sensors failing. If the speedometer still works, then it is usually the
input speed sensor that has failed. If the speedometer no longer reports a
speed, then it is the output sensor. Both sensors are about $25 each at the
dealer and fairly simple to change (5 minute job). On the Chryslers, they
tend to fail often. I've replaced two in different vehicles and each had
about 50-60K miles. Another common failure in Chryslers is the solenoid
pack.

If the Blazer is anything like the Chrysler trans, if it fails and does go
into 2nd gear, do not drive it far or long since it places a great deal more
stress on the internals. Many people I know who started with a simple $25
part that needed to be replaced have ended up requiring rebuilt
transmissions at up to $2500. Again, I'm not sure if this information is
useful or not, but have to believe that the designs are similar and may even
share third party components, such as the electronic speed sensors.

Good luck!

Bob

"JURB6006" wrote in message
...
One new question;

Just exactly happens if the power is lost to all solenoids ? Fuse blows,
what
it just revs up and sits there, or does it take off in second or third and
disable passing gear, ummm, for example.

Reason I ask is that some other similar vehicles have experienced taking
off in
second and the dash went out. This has been found to be the ignition
switch in
a couple of cases. Really if the fuse blows it's blown, but a switch.In
this
case the vehicle doesn't have the digital dash (IIRC) and being a 4WD it
might
just have a seperate VSS for the speedo.Now I'm not trying to shove a
symcure
down your throat, but I think test one will be to see if power applies to
the
topside of those solenoids.

Believe me, when I get back under the thing I'll check those connections,
and
if that proves nothing I'm going to find out what is and is not being
driven.

With your advice I'll definitely make sure the electrical end of it is OK
before money droppage.

I will do what you suggested, soon, but if you happen to know, if it were
to
lose all power to the solenoids, what would it do ?

I think this is a crucial piece of information here. Can you drive home
with
the tranny fuse blown ? This also comes back to the ignition switch if it
applies the voltage TO the tranny fuse.

If the tranny is reporting to the PCM what gear it's in, WHY ? Because it
still
has valves, and maybe a pure hydraulic mode to get you home ( ? ? ? ? )