"Doug" <sparks06524nospam@[EMAIL PROTECTED]
> wrote in message
news:7j1o14lrdkg4is41fdmcv48ej6mbiracp9@[EMAIL PROTECTED]
> On Wed, 30 Apr 2008 06:15:20 -0400, Bill Putney <bptn@[EMAIL PROTECTED]
>
> wrote:
>
> >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
>
>
> Ted,
>
> Thanks for your input but NO, it definitely happens ONLY during
> wet/damp/high humidity days.
>
> I've driven the vehicle under multiple conditions on dry days and
> operation is perfect.
>
> Another clue is that OCCASIONALLY when the transmission slaps into
> limp mode, the window wipers will start operating when their control
> switch is in the off position.
>
> I'm thinking ground, connector corrosion and/or an alternative current
> path.
>
But you already said:
"...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...."
Either you did this or you didn't. Which is it?
> Now, could the output of that speed sensor be intermittent on damp
> days? Sure it can if there is some corrosion, etc on its wiring.
> I don't know how to explain the apparently simultaneous wiper problem
> unless there is some common ground point that begins to float.
> That doesn't seem to be the case per the tech manual.
>
> Nevertheless, you've given me some additional hints.
>
> What is the physical location of the transmission input and output
> speed sensors for a 1996?
>
Right under the trans input and output fluid cooling lines in the front.
All years of these trans are the same in that regard and your tech
manual should have the info, unless it's not a real tech manual?
Frankly it sounds to me like you didn't clean anything having to
do with the transmission control system. Maybe you thought you
were doing it but you didn't. The trans computer and the PCM are
completely different computers.
You really need a factory shop manual. EBay has many of these.
Or get a subscription to Alldata it's only about $25 bucks.
I do not know 100% on the 96 but I think it is just like the earlier
vans where the trans computer is mounted on the firewall. Right
under the water seal that is between the back of the hood and the
metal frame right under the winshield. If that seal is missing or loose
then your basically pouring a garden hose of water on top of the
big fat many-contact trans computer connector every time it rains.
If you did not separate and clean out this connector with contact
cleaner followed by WD40 then that should point you to where
the next thing to investigate is. The connector does have a water seal
on it.
> Doug
>
>
> >
> >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 -
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.
> >
> >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.
> >
> >Bill Putney
> >(To reply by e-mail, replace the last letter of the alphabet in my
> >address with the letter 'x')
>
> Thanks for info on the sensor locations.
>
> I'll crawl under and pull the connectors to check.
> If they are exposed to moisture, it could explain the situation.
>
> As mentioned, operation IS perfect on all dry days.
>
> The transmission was rebuilt less than 10K miles ago and the solenoid
> valve pack was replaced.
>
> Doug
>
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