"Bill Putney" <bptn@[EMAIL PROTECTED]
> wrote in message
news:67qv5jF2lt22uU1@[EMAIL PROTECTED]
> Ted Mittelstaedt wrote:
> > "Doug" <sparks06524nospam@[EMAIL PROTECTED]
> wrote in message
> > news:778g14pqvjl19jsosismr1f4h20q0es752@[EMAIL PROTECTED]
> >>
> >> A friend has a 1996 T&C with the 3.8l engine.
> >>
> >> On damp or rainy days, the transmission suddenly kicks down into
> >> second, even if the vehicle is going at a high rate of speed -
awkward
> >> on the highway. From the technical literature that I've read, it
seems
> >> like it's going into the limp home mode.
> >>
> >> From the wiring diagram in a similar year tech manual, there are
quite
> >> a few sensors and/or connections that can activate the kickdown
relay.
> >>
> >> We took the van to a local Chrysler dealership and they insisted that
> >> the problem was caused by a bad alternator.
> >> The only thing wrong with that alternator (which I already knew) was
> >> minor bearing wear. I insisted that replacing it wouldn't help the
> >> transmission problem. They insisted that since I was not a "factory
> >> trained tech", I didn't know what I was talking about.
> >>
> >> My friend paid to have the alternator replaced and of course it
didn't
> >> help. One week later in the rain, the transmission kicked down again
> >> at 65 MPH. On dry days, all is perfect.
> >>
> >> I asked the dealer service manager if they had scanned the error
codes
> >> and he replied saying "we did was was required".
> >>
> >> Needly to say that my friend and are are disgusted with the
> >> dealership.
> >>
> >> I've pulled apart and cleaned with electronic contact cleaner all
> >> connectors to the power control module, pulled all relays and fuses,
> >> the PCM, visible sensor connections, etc to no avail.
> >>
> >> Anyone have any suggestions?
> >>
> >
> > anytime the trans goes into limp mode a code is set. I think the
> > dealership saw an opportunity to make some money since I am quite
> > certain they sold your friend an alternator at a cost far in excess of
> > a simple rebuilt unit. Naturally if they didn't scan the trans then
they
> > would not be able to tell you the code that was set!
> >
> > Anyway, I own 2 T&C's a 94 and a 95 and done considerable work
> > on them. I would strongly recommend you replace the
> > "turbine sensor" aka input speed sensor. These hall-effect
> > sensors get intermittent when they get older and will cause this
problem.
> > I actually think that they are the only part in the transmission that
will
> > cause this without an accompanying other symptom, such as a big
> > grinding noise or some such. For some idiot reason known only
> > to Chrysler's transmission designers, the software in the trans
computer
> > will immediately slam the trans into limp mode even at a high rate of
speed,
> > if the signal is lost from the input speed sensor for even a fraction
of
a
> > second, and if signal reappears from the input speed sensor it will
> > -keep- the trans in limp mode until you shut off and restart the car.
> >
> > I would discount the rain issue, frankly. The fact of the matter is
that
> > unless your going at a high speed, it is not easy for your typical
> > ignorant driver to even be aware that the trans has shifted into 2nd.
> > I strongly suspect that this trans has been doing this for some time
now,
> > and your friend has somehow made some unconscious assumption that
> > it is due to water, so now he only notices it happening when it is
raining.
> >
> > Ted
>
> I will add to what Ted said to say that there is a second speed sensor -
> the output speed sensor that will cause the cause the exact same
> symptom, plus on some vehicles, like LH cars, the speedometer reading
> will go to zero when it's the output sensor vs. the input sensor - I can
> only assume the TC is like that too - same tranny - I assume the output
> speed sensor is used to derive the speedometer signal in the TC too
It is, on most of them. Only the very early vans used a mechanical
speedo connection to the trans, like the first 3 years I think. Long
before
96. In fact, in 96 I think they also did away with the mechanical
gearselector connection from the gear selector knob - the mechanical
"feel" of the selector on the steering column is a completely fake
farce for humans who grew up with mechanical trans linkages.
- if
> that's the case, if the speedometer didn't also act up, the problem
> would likely be the input sensor - the one towards the front of the
> tranny. The sensors themselves go bad, but also you should try cleaning
> the connectors (two wires each) at the two sensors first - on the left
> side of the tranny - access from underneath. The sensors are about $20
> each and are easy to replace - they take a 1" wrench - socket or open
> end might be easier depending on access angle in that vehicle. They're
> plastic, so don't torque them - just snug them up - they have o-ring
seals.
>
I've had the input speed sensor fail 3 times, one
time on one of my vans, the other 2 times on the other van, and none of
the
3 times the output sensor failed. Do the input sensor first, and if the
problem doesen't go away, then do the output sensor - unless as Bill
said, you noticed a speedo problem.
As Bill says, the sensor contacts should be checked. Also, the input
sensor is right under the trans cooler input and output fluid ports - it's
rubber
hoses that connect to those ports and if the clamps get loose you get
fluid
leaks that go right onto the sensor and dissolve the rubber connector
that houses the wires to the sensor.
> This kind of problem can also be caused by a bad solenoid valve pack -
> that's a little more involved (time + $$) to fix. As Ted said, the
> codes might tell you something on that.
>
Yes, it can - the electrical connector to the valve pack should be taken
apart and cleaned, etc.
Ted
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