91 Voyager transmission Goes Into Limp Mode

On long trips (over 100 miles or so) the trans intermitently goes into
limp mode (stuck in 2nd gear). When it does this, I have to
stop,shut-off the ignition,start again, and then it goes through the
gears. At the next stop light the process starts all over again. This
does not happen on short trips around town. My transmission guy says
that my transmission control module does not have cooling fins and he
has never seen a plymouth module without cooling fins. He thinks that
on long trips heat build-up is breaking down some components inside the
module. He road-tested the trans and it was working good. The only
thing that the code readout says is the trans is going into limp mode.
He'll install a new module with cooling fins for $300. Has anyone else
had this problem? I'd rather not get into the "Let's try this and see
what happens routine."Thanks in advance,Ron

 

There are pertty much 3 things that ou can have problems with:

1) The trans itself. These puppies break. And if you are on a
non-rebuilt 1991, well chances are you are living on borrowed time.

2) The TCM. Again, if your TCM does not have fins, then it surely is
very old. The newer one with fins can be "flashed" to the latest
firmware for your van.

3) Wiring / Cable Harness. Corrosion on connectors, or even a bad wire
after all these years.

If you are worried about the cost, then why not go to a wreker and see
if you can get a TCM with fins from a similar van? Perhaps a 94 with
the same engine as you have? You could pick that up for cheap, and
give it a try.

Baring that, wiring problems can be a pain in the ass to find.

Do you have a trans oil booster cooler installed? If you trans is on
its way out, perhaps when the fluid gets thoroughly heated it starts
to fail.

 

ron wrote:
............................................................... The only

Ron,
There are no codes that say "I'm going into limp-in mode but don't know
why" There are 44 codes and of these, 32 will cause limp-in mode. Each
of these 32 gives a likely cause of a problem, and gives the technician
a place to start his diagnosis. The Chrysler Powertrain Diagnostic
Procedures manual gives a step by step troubleshooting procedure for
each code. If you'd like a list of the codes I can send you one. If you
can supply me with the actual code(s) that are stored I can also email
you the diagnostic procedures.

 

Steve wrote:> ron wrote:>
............................................................... The
only> > thing that the code readout says is the trans is going into
limp mode.> > He'll install a new module with cooling fins for $300.
Has anyone else> > had this problem? I'd rather not get into the "Let's
try this and see> > what happens routine."Thanks in advance,Ron> >
Ron,> There are no codes that say "I'm going into limp-in mode but
don't know > why" There are 44 codes and of these, 32 will cause
limp-in mode. Each > of these 32 gives a likely cause of a problem, and
gives the technician > a place to start his diagnosis. The Chrysler
Powertrain Diagnostic > Procedures manual gives a step by step
troubleshooting procedure for > each code. If you'd like a list of the
codes I can send you one. If you > can supply me with the actual
code(s) that are stored I can also email > you the diagnostic
procedures.Steve,From what I hear, the old TCM's (with no cooling fins)
don't give any information other than "I went into limp-in and I'm not
going to tell you why".I'm going to try a new EATX Relay first before
getting a new TCM. My transmission guy says there is nothing wrong with
the trans that he can see. The trans was completely rebuilt at 135K
(I'm surprised it lasted that long) and there is 25K on the rebuilt.
The one good thing about this van is the 3.3L V-6 that has 160K and
burns very little oil, leaks none, and runs strong. The only thing
wrong with the 3.3L is trying to change the 3 plugs in the back.Thanks
for the info,Ron

 

Steve wrote:> ron wrote:>
............................................................... The
only> > thing that the code readout says is the trans is going into
limp mode.> > He'll install a new module with cooling fins for $300.
Has anyone else> > had this problem? I'd rather not get into the "Let's
try this and see> > what happens routine."Thanks in advance,Ron> >
Ron,> There are no codes that say "I'm going into limp-in mode but
don't know > why" There are 44 codes and of these, 32 will cause
limp-in mode. Each > of these 32 gives a likely cause of a problem, and
gives the technician > a place to start his diagnosis. The Chrysler
Powertrain Diagnostic > Procedures manual gives a step by step
troubleshooting procedure for > each code. If you'd like a list of the
codes I can send you one. If you > can supply me with the actual
code(s) that are stored I can also email > you the diagnostic
procedures.Steve,From what I hear, the old TCM's (with no cooling fins)
don't give any information other than "I went into limp-in and I'm not
going to tell you why".I'm going to try a new EATX Relay first before
getting a new TCM. My transmission guy says there is nothing wrong with
the trans that he can see. The trans was completely rebuilt at 135K
(I'm surprised it lasted that long) and there is 25K on the rebuilt.
The one good thing about this van is the 3.3L V-6 that has 160K and
burns very little oil, leaks none, and runs strong. The only thing
wrong with the 3.3L is trying to change the 3 plugs in the back.Thanks
for the info,Ron

 

ron wrote:
From what I hear, the old TCM's (with no cooling fins)

The only difference I know of between the TCM modules with and without
fins is that the older finless modules can't be flashed, they require
the chip to be changed to update it. I had a 1991 Gr. Voyager, and still
have a 1992 Gr. Voyager. Both finless TCMs store codes quite well, as
I've pulled codes from both.

 

Another BIG difference is the new one will not allow the trans to go to limp
over 45 mph. On the old one you could be 90 and if a fault was sensed there
would be engine parts all over and your lip prints on the windshield ;-)

 

I have to burst your bubble and tell you this isn't true. Perhaps on the
1996 and
later units they put that in, but the UPDATED 1995 and earlier TCM's will
happily knock you down into limp mode, on the freeway, at 60Mph. I know
this from experience. And despite the fun imagery, going into limp mode at
60Mph doesen't spit engine parts all over the place. Perhaps at 90, but can
you even get a minivan to go 90? (other than the turbo ones)

Ted