Help - Diagnostic Bus not working!

The "Diagnostic Bus" that the dealer plugs into to get codes from the
trans and the engine on my 1995 GC is not working properly. Does
anybody have any experience with what can go wrong with that bus or
the best way to troubleshoot it?

Background -
I had a reman (Chrysler remanufactured) trans installed 9 months ago
by Chrysler, (for...uhg! $3000). It doesn't always shift properly at
freeway speeds, and the Dealer now says that since the "Diagnostic
Bus" doesn't work, they can't get any of the diagnostic codes and
can't do anything. They are willing to repair the bus for ~$160. I
know the bus worked before the repair, and I assume it worked after
the repair.

I thought paying Chrysler $3000 for a reman trans while we were
stranded 1200mi from home was an investment against future
tran$mi$$ion repair$, but I'm learning how expensive it really is to
work with Chrysler and their best independent dealers.

Any constructive help is appreciated.

Thank you,
- Duane

 

After authorizing the dealer to repair the bus, they now informed me
that the bus is working and doesn't require repair. Now I'm getting
the run-around on the Chrysler repair warranty. Makes me want to buy
a Honda or Toyota.

 

Oh, you would rather get the runaround from Honda or Toyota when
they goof up something like this, eh? Because that's what happens with
them too in these situations. And keep in mind your not "working with
Chrysler" your working with the dealer. Anyone, even you, can walk
into the dealer parts counter and buy a Chrysler reman transmission over
the counter and take it home and install it yourself. The factory can
do the best reman job in the world but if the techs at the dealership are
bozos, they can screw it up. And also keep in mind the dealer that your
working with is NOT the bozos that installed this reman transmission.
For all you know they used a hot glue gun instead of bolts to mount
the transmission! So have some more sympathy for the dealer that's
working on it, they are cleaning up someone else's mess and that's never
fun.

When they replaced the transmission, did they replace the transmission
computer? Check the invoice and see if they did. They may not have
properly
set the pinion factor. If they couldn't get their DRB scanner to work with
the
CCD bus connector then they may have just slapped in a "reman" computer
and left it at the defaults.

Sometimes the socket that the DRB scanner plugs into gets loose and
the tech plugs the DRB scanner in, and the weight of the cable hanging
on the connector pulls it out a few seconds later enough for it to not
make contact. If the tech knew what they were doing they would check that.

Unfortunately, your in a hard place here. When a vehicle breaks down 1200
miles from home with a major failure of this magnitude, most people have
limited
options. With the Blue Book on a 95 GC, you literally would probably
have been better off just trading it in at the dealership you had it towed
to, and buying a '97 or later GC with a warranty on it. Some people (like
myself) might have found some convenient place to park the thing, then
flown home and rented a car dolly then driven back with my other vehicle
that has a hitch on it, and towed it home. But spending $3,000 on any
repair
at a repair shop that's 1200 miles away is a huge mistake, in my opinion.

Also more importantly, my brother-in-law works at a Dodge dealership and
they rebuild these transmissions. I would expect that any decent Chrysler
or Dodge dealership would be able to do so as well. In my opinion you
would have been better off having the transmission that was in your van
rebuilt rather than getting it exchanged for a reman. The first clue that
you
were NOT dealing with one of Chrysler's "best independent" dealers was
that this so-called best dealer couldn't even rebuild a transmission that is
one
of the most common transmissions Chrysler uses! Ask the current dealer
your working with, I'd bet they can rebuild them.

If you post more specific info as to what the problem is we might be able
to offer suggestions.

Ted

 

there is a chance there is a blown fuse and the bus has shut down from it

i see it all the time. and if they are using the wrong sofware in the
scan tool it can say the same thing no buss comm.
since the trans job is under warranty take it back and let them fix it
under 12/12000
since it's not shifting right don't let them scam u maybe they already!
did if the bus is down then the trans might not work right and they
reconmmend a new trans when a wiring repair was the correct fix to begin

 

the tech works on a flat rate pay meaning u paid him 9 hours to replace
the trans
and now he has to work on your car for free and the shop does not want him
to work for free since it will take him away from work the does pay
get in their face

 

And keep in mind your not "working with

The Computer was reflashed, but not replaced. The Bus was working,
and now it is again. The transmission was rebuilt 55,000 mi earlier
by another dealer. I had it back to him 2 years later when the pump
was whinning and he said the pressures were low, but it was out of
warranty. He recommended a reman to do the job right.

I thought of that, but we (wife, 2 children and I) were on a 1 week
vacation. I also considered renting a U-haul and a dolly, and towing
it home. The van was still drivable at that time, but it was slipping
and shifting poorly because of low pump pressure. The low pressure
was probably the O-ring around the converter that I had leak on
another Chrysler with the A604.

my opinion.

Ted, your right and that's a good idea! I went to the largest
Chrysler dealer (according to them) in Orlando, FL just so that I had
a warranty at home.

The dealership I worked with in Orlando, FL appears to be much more
competent than the one in Bloomfield Hills, MI. They promised the job
would be done in 1 day and it was. I realize in hindsight that this
may sound silly, but it was important not to ruin the entire vacation.
The dealer in MI had my car 4 days, didn't call me back as promised,
couldn't diagnose which half shaft is worn without actually replaceing
them and declared that the diagnostics bus wasn't working. Only after
I agreed to pay $160 to repair the bus did they try it again and
mysteriously found it works fine.

Ted, you sound very knowledgeable and have some good suggestions.
Thank you.
I'm frustrated with Chrysler transmissions and the problems I've had
with them. I've learned a lot about the A604 from having 2 Chrysler
vehicles that use them. I like to maintain my cars and keep them for
many years. I've been a Mopar fan for many years, but these last 2
Chrysler vehicles have suffered from some poor designs and substandard
OEM parts. I have had to "replace" the transmissions more frequently
than I replace the sparkplugs! The '89 Plymouth Acclaim required 4
transmissions (215,000 mi when I donated it) and this '95 GC is on
it's 3rd with 165,000mi. The O-ring on the converter has been the
problem on many of the A604 failures. It's a shame that Chrysler
makes over $800 on the rebuild kits alone, and they apparently sued
the company that made a better O-ring.

The transmission and engine in any car over $25k should last at least
100,000mi with normal maintainence. Only the 4th A604 in my Acclaim
lasted 90,000 without a "limp". It had the better aftermarket O-ring
and was still working with ~95,000 miles on it when I donated it.
Many Chrysler cars have very low resale values because of the
A604/A606 failures that are all too common.

- Duane

 

"pump whining" is NOT caused by low pressures, it is caused by
improper torque converter installation. What happened is that when
they separated the transmission from the engine the first time around they
replaced the torque converter - and the new converter was slightly "thinner"
than the old one. As a result when the transmission was re-mated to the
engine, there was too much clearance between the flexplate and
the converter, so when the converter was tightened down to the
flexplate, it was pulled too far out of the transmssion.

If this happens they are supposed to separate the transmission again
enough to install shims (washers can be used) on the converter bolts.
This adds time to the install process and is annoying as you can imagine.

If the converter is pulled too far out the front pump bearing wobbles and
causes the whine eventually, and the bearing fails early.

Someone was rushing the job and pulled the old "if it's good enough for
government it's good enough" attitude and essentially knocked 50,000
miles of life out of what might have otherwise been a perfectly good
rebuild.

There's pros and cons to a rebuild vs remanufacture. Unfortunately
most of the pros of a reman are pros for the shop, and most of the
cons of a reman are cons for the customer.

Another thing to keep in mind with rebuild vs reman and that is what
I call the "value add" of the job.

There's basically 3 major value-adds to any transmission job. The
first is the diagnostic of whether or not it can be fixed in-vehicle or
whether it needs to come out. The second is the actual work of in-out.
The third is the actual work of tearing it down and rebuilding or
remanufacturing it.

By far the most profitable value-add is the rebuild/reman. What this means
is
that the orginazation that does the rebuild gets the largest chunk of
profit money. So, the upshot is that if a repair shop never rebuilds
the transmission and just buys remans all the time, the bulk of the profit
of the job isn't going to the repair shop, it's going out the door to
someone
else. Thus for the shop to make money, they can't pay a lot to their
people, this in turn drives away skilled mechanics and attracts the
unskilled parts-changing mechanics.

This "follow the money" philosophy is in all businesses and markets.
It is why you don't generally find experts checking in the grocery
stores, but you might find them working for the grocery distributors,
and your definitely going to find them working for the manufacturers of
the products in the grocery store.

When hiring people and companies to do jobs for you, if you try to get
as close as possible to the folks getting the biggest value add out of
the product you are buying, your going to be dealing with far more
knowledgeable people. This doesen't matter much with a product like
milk, which is why everyone buys it from the grocery store. But it
does matter with any product or service that is complex.

repeat after me "it's just a box with wheels that gets me places"

Beware getting emotionally involved in a vehicle purchase. You could
have sent the wife and kids off for 3 hours to play and handled the
entire thing yourself. And as a benefit that would give the wife
something to complain about for the next 3 years (being excluded
from the vehicle purchase) and you have to give wives things to
bitch about every once in a while to keep them happy, or they
stop thinking your a typical asshole male, and that really bugs them. ;-)

Hindsight and armchair quarterbacking is easy I know. Fortunately I've
never been in the car hotseat on a vacation yet, but I've watched my dad
sweat bullets a few times years ago when my parents were shuttling the
family around on auto vacations. Taking that shortcut through New
Mexico might have seemed a great idea at the time, but it's a guarenteed
coronary when your 60 miles from anything that can remotely be called
a village, city, town or cellular tower and the alternator light goes on.
And
it's raining. And the last vehicle you saw going the other way was 3 hours
ago.
Filled with Mexicans fresh from over the border. And your wife is telling
you to
pull over and wait for the police to come help out. (fortunately for us, by
age 15 I knew enough about cars to guess the fan belt had snapped and
to tell him to turn off the lights and accessories and just keep going)

Ah, but it wouldn't have been ruined for wife and kids, just for you. ;-)

Your welcome. I've been interested in these transmissions ever since
we bought our first minivan, it is a design that actually uses a car
computer
for something other that stupid bullcrap that nobody cares about.
And I had to read up on them when I did the in-and-out on the
transmission in our '94 T&C.

I wouldn't put a lot of stock in stories like that. The Chrysler
transmission
manual only has 2 o-ring redesigns listed on the front hub, both in 1989.

Here's the problem with the Ultradrive in a nutshell: Big heavy vehicle
with lots of torque, tiny tiny space to put a transmission into. They
basically stuffed a transmission that has hundreds lbs of torque going
through it into an area about the size of a square foot. Then to make
things even more fun they insisted on throwing an extra gear into that
space. And a differential right next to it. Literally, you can hardly get
your head into the space occupied by the transmission, once you pull it
out.

The Ultradrive has been out since 1989 so we now have a lot of history
to look back on and see what was wrong. For starters, unquestionably
any A604 manufactured before 1996 has a snowballs chance of surviving
past 100Kmi. espically in a minivan. You hear a few stories from now
and then about the miracle transmission that lasted 150K mi, but people
remember and repeat those stories because they are so rare. There's
tons of '95 and earlier vans for sale used these days with the label
"transmission
trouble" in the description. The Chrysler factory transmission book lists
dozens of parts redesigns on these earlier Ultradrives.

Secondly there's the fluid issue. Early Ultradrives had Dexron stamped
on the dipsticks although it was never a factory fill in these
transmissions.
Chrysler itself went through several ATF formulations before arriving at
ATF +4, which was about a -decade- after the trans was introduced.
It also didn't help that the fluid change interval schedule published early
on was far too infrequent. Chrysler also found programming
mis-assumptions in the trans computer which caused the fluid to wear out
faster. And last but not least, in the earlier pre-96 minivans, the stock
trans fluid cooler is inadequate.

All of these problems have answers, and the aftermarket has come up
with rebuild kits that work very well. The problem is that these
transmissions
are a minority compared to GM products, and most rebuilders
don't have a lot of experience with them. But there are many that do
very good jobs. When I put in my rebuilt A604 last summer, it came
with a year warranty, and it was rebuilt locally, not by Chrysler. You
can see pictures of the process here:

http://www.freebsd-corp-net-guide.com/94tcpics/project.html


Ted

 

what a crock of shit TED there is air in the system and that is the issue
either the valves are the source or the convertor/ pump internal is the cause
not how it mates to the flex plate if the was the case then there would be all
sorts of knocking noise such as the one i just fixed in my garage for someone