93 3.3 Dodge GV

Had this problem once before and thought a junkyard computer fixed the
problem, but maybe not. You're driving down the road and the car dies.
It'll crank fine, but won't start. Fuel pressure is fine. Last time we had
it towed to a dealership. They 'thought' it was a bad computer, however
they got it started by disconnecting the pcm connector and reconnecting it.
I replaced the pcm with one from the junkyard, same model, numbers etc. The
van worked fine for about 6 months. We also had a problem where, while
driving on the highway, the speedometer would go to zero and then right
back. You could feel the trans re-engage. This too happened very
infrequently. Someone on this board thought it might be the trans output
speed sensor.
What I'm wondering, is if this sensor problem could have caused the car to
die and it not be the pcm ? Seems strange that 2 pcm's would go bad and
especially since the majority on this board think these pcm's very rarely
fail. I've had it towed to another dealership to see what they can discover.
I think this dealership has a better service department. We'll see what
they can come up with.

thanks,
nick

 

After they disconnected and reconnected the pcm connector did it fail again
before you replaced the pcm with your wrecking yard one? I'm wondering why
you messed with the pcm if they got it working.

We also had a problem where, while

A possible cause is the crank position sensor. It is mounted on the
transmission in
the back, you have to get to it from the bottom. If that fails you get no
spark
which is what it sounds like your problem was.

The output speed sensor is a different location, and that is a common
problem
for the speedo doing that.

Since both the crank position sensor and the output speed sensor share a
wiring harness I would wonder if perhaps the wiring harness somehow got
loose and contacted the exhaust manifold which melted the insulation and
shorted some wires.

Frankly there's no substitute for basic troubleshooting. Did they even
bother
pulling a plug wire and using a test plug on it to at least see if the car
was
generating spark when you turning it over?

Ted

 

Nick,

The speedometer problem could be a tranny speed sensor, but
strange that it would come back again. My experience has been that
when they die, they die. Maybe it is a loose connection to the sensor.

Don't think the bad sensor should cause the car to quit. It will only
cause the computer to go into "limp" mode - low gear only.

Maybe they are unrelated issues.

Roger

=----

 

The dealer called and said it was the pcm. I find it hard to believe that
this pcm, even though junkyard bought, same numbers, would go bad, but I
guess it is possible. People on this board have said these pcm's very
rarely go bad. The scary part is that the car died about 6 months ago, the
other dealership said it could be the pcm, but got it started again. I
bought the other pcm and put it in and it ran until now and then the car
died again. They couldn't get it to start today. I did not like the other
dealership telling me it was the pcm but then got it started. The fact that
this dealership can't get the car started indicates that it might be a hard
pcm failure. At this point I'm not sure. The old pcm died and then ran,
maybe intermittent problem, however made the vehicle unreliable. The
replacement pcm ran fine for 6 months then died and stayed dead. Maybe I'll
spend a little more and get a refurbished pcm and try that.

Comments and ideas welcomed
nick

 

If the car's been eating pcm's I would look carefully at the wiring loom.
It really
sounds like the loom is shorting against something. If that is OK then your
battery
connections might be bad, or cabling to the battery. The battery serves as
a natural
surge suppressor in a car electrical system and if connections to it go bad
then you
can have spikes and such on the electrical system. Also maybe the voltage
regulator
is intermittent and letting the alternator overvoltage the system
periodically.

Ted

 

Check all the grounds as well.

Bob

 

Thanks for the tips. I brought the old pcm to the dealer and they put it
in. The car started. Then they put the old one back in and it wouldn't
start. So the 2nd pcm is dead. I asked about the pcm going bad and that
maybe something else is causing the pcm to go bad. The other ones not dead,
but it did die 6 months ago. So I told them to spend another hour or so and
check to see if their diagnostics tells them anything, of course with the
pcm that works. Hate to junk it, but then really would like to find the
problem. I just may get a third pcm and run it until it dies again, if they
don't find anything. Any thoughts on going back to a junkyard or spending a
little more and getting one at NAPA or AutoZone ?

thanks again,
nick

 

I think your getting an education in what shotgunning is all about.

The swapping of PCM's is not a real test. If you really want to find out if
the
PCM's are bad or not, go find another 1993 3.3L Dodge GV that has NO
history of trouble with it's PCM and do the PCM swapping with it. I would
bet that both PCM's would work in it.

This problem really points to wiring issues or an intermittent sensor. Your
computer
is older and as a result it does not double check all sensors. So you can
have problems
with sensors or wiring or other electrical components that do not set a
code. The
computers in the new cars these days are a lot more sophisticated and will
usually
set codes if there's a problem. Your dealership techs are used to that kind
of
vehicle and are apparently helpless when faced with the need to do some real
diagnostic work.

Has anyone done even the most basic troubleshooting? Such as cleaning the
contacts
on the pcm and harness that plugs into it? And using a voltmeter to check
the voltage
going to the pcm to be sure it's getting a full 12 volts of power? And
using a scope
on the crank sensor to see if when the engine is cranking that the sensor is
sending
pulses to the system?

Plugging a scan tool into the system is a first step. But it is not the
last step.

You can try another pcm if you really believe that it's intermittent.
Frankly I don't
think that a wrecking yard pcm is any better than a so-called "rebuilt" pcm.
Bear
in mind that most of the pcm is dense integrated circuits and you need a
tech
qualified to do multilayer circuit board soldering and unsoldering and can
diagnose
computers at a hardware bit level to repair them, the minimum cost of entry
for even
the tooling to do this is $50K. These "rebuilt" pcms you get are simply
wrecking yard pcms
that the rebuilder buys pallet loads of and tests out, and if they test out
OK they clean
them up and sticker them for sale. They might replace a burned diode or
power transistor
but that's as far as they go.

Ted

 

thanks Ted, I have done some basic things, like unplugging, cleaning and
plugging back some connectors, taking the pcm connector off and inspecting
the pins and then putting ox-gard on and reconnecting. I did look at some
of the wiring to see if I could spot an obvious problem (bare wire, loose
connection, etc.) but nothing extensive. Haven't heard back from the dealer
yet, so I don't know if they found anything or not. I'll keep trying.

So you think that if I plugged the pcm that will not start my van into
another same vehicle, that it might start. Interesting, I just assumed that
swapping each in my van and one starting and the other not, proved one pcm
was dead.

thanks again,
nick

 

This is only a suggestion... I don't work on cars anymore.. (too old and
fat) however I do still play with them occasionally. A neighbor had a
similar problem and a friend and I worked on it to trying to help ..

Well to make a long story short she was ready to junk the car,, had gone
through all kinds of problems and dealers and places as you.. My friend
(electronics wiz) put a data recorder in the car to check the voltage.. in 4
different locations (same time)while she used the car.... turned out every
once in a while the voltage would drop to about 12 volts in the system while
the vehicle was running... not enough to set any codes but enough to drive
the computer nuts... trans downshift.. speedo crazy... Anyway it turned out
the brushes in the alternator were bad (worn) and losing contact once in a
while...

As Ted already mentioned ... you really need someone that can get down to
the nuts and bolts of troubleshooting... somewhere out there are still some
guys that know how to use the computer between their ears and get stuff
done... There are an awful lot of parts in a modern auto..could cost some
real money to change them all

 

No, because if there's a problem in your van then it could be the cause, not
the part your swapping.

Substitution of components is a good way to test for a bad component, but
you have to fully understand it. The more complex the system your
substituting the
less chance a diagnosis is firm.

For example you see a broken bolt and you substitute it - you have 100%
proof
that the bolt is broken (although you may not know why it broke) and needs
to
be substituted. But a pcm is far more complex than a bolt.

for another example you have a problem and you diagnose
it as a bad alternator, then replace the alternator with a new one and the
problem
goes away - that's substitution. However, it's not proof positive that the
alternator
was the only thing that was bad. It's like 99% proof. But that vital 1%
isn't
going to go away until you run on the good alternator for several months and
nothing
bad happens. If you tear down the old alternator and find fractured
components
then that really decreases chances it's something else. But if you tear it
down and
find nothing wrong other than diodes - and the diodes that are burned are
really
high quality ones not cheapo junk ones - well that now increases it's chance
that
something else in the system is also broken and just took the alternator
with it.

In your case the original diagnosis was a bad pcm so you swapped it, but
that only got
you a 99% chance of proof that the original pcm was bad. As you discovered,
when the
second pcm went bad and you brought back the first one, it worked. Thus,
that vital
1% is now indicating that there's a possibility that something else is bad.

You probably have a solid 80% chance that the original pcm is just
intermittent, and
more like a 50% chance that the second pcm just didn't last and is truly
dead. But
enough of a chance exists that it's something in the van that there is no
proof positive
that the first pcm is intermittent and the second pcm is just dead.

If you tested both pcm's you have in a known good van then you would have
that
proof positive.

The task now is to do additional troubleshooting of the system (NOT the
pcm's) If
you can eliminate enough other things you will decrease chances it's
something else and
increase the solidity of the diagnosis that the 2 pcm's are just bad. That
is why I
pointed you to the crank sensor and some other parts that have higher
probabilities
of failure. If those can be tested and found good it will help to be sure
that you won't
be throwing more money away on more pcms.

Ted

 

Thanks Ted and me!;

The dealer called me this morning and said they spent about 2 hours checking
the van. They checked the wiring, the sensors, and whatever else they could
check. They did not find anything out of the ordinary. No sensors out of
range, wiring appeared ok, no shorts, everything looked good. The vans got
212k on it, but still runs great (outside of this problem). He was pretty
honest and said if it were him, he wouldn't put a lot of money into it.
They said 'run it until it dies'. Since this original pcm died on me once
and then somehow came back to life, I'm a little nervous about it's
reliability. So I may spend a little more and get a rebuilt pcm from NAPA
or AutoZone and see what happens.
This dealer really impressed me by taking the time to run the diagnostics
and being pretty honest with me. They could have said $490 plus labor for a
new pcm and left it at that. Instead they told me what they thought I
should do and then left it up to me.

hey, thanks again for all the tips and comments, I really appreciate it,
nick

 

Hey. they aren't dumb - old guy comes in with a 93 GV with
210K+ miles on it - they know your probably going to be shopping for a new
one in another 20-50K and they want your business! ;-) And old guys
tend to know a lot of people in the community and talk to 'em. ;-)

Seriously, you might just take a look at what they have on the used
lot and consider doing a trade-in, or buying a used one and selling yours
via private sale, rather than buying another pcm. Since yours is running
well now, but you have reason to believe there's a potential for failure
there, nows the time to sell. I've personally been burned once by holding
onto a vehicle that I knew had some potential trouble but I was lured by
the thought that I might be able to squeeze just one more year out of it.
Of course the damn thing broke down before I planned and once that
happens the only people who are going to buy it out of your driveway
is the wrecker who wants it for scrap steel.

It might only cost you a few grand and you might end up with something
almost 100K miles younger. There's lots of 94 & 95 minivans out there
around the 110-120K age bracket right now. And generally after the 10
year mark used vehicles take a significant depreciation drop. It certainly
doesen't hurt to look. And we are getting toward the optimal time to buy a
used vehicle espically from a dealership. Around about January, the
dealerships are
full of used vehicles they have taken in trade from people buying new ones,
and since it's right after Christmas, most of the people who would normally
look for a used vehicle are tapped out from Christmas and they haven't
got their tax refunds yet. You could buy another van then just park yours
in the driveway for 2-3 months as a spare until your sure the replacement is
good, then sell it when vehicle sales pick up a few months later.

I personally think the 91-95 years were really good vintage in those vans,
with the only weak point being the tranny, and ABS (with the exception
of 94 1/2 - 95 which was a different system) if it has it. Stay away from
the 96-98 vintage, Chrysler did a major overhaul in 96 and changed a lot of
things, and they were still diddling with the tranny in later years until I
think
they got the last of the bugs squished in the 2002 timeframe.

Ted

 

Hey, thanks everyone for the great replies and suggestions. Ted, you're
probably right, I should consider dumping it. It's tough, because I know
what I've replaced,fixed and repaired, and probably too attached. It's
e-check time and that might be the 'last straw' -- if it fails, I may park
it and look for a replacement.

thanks again to all,
nick

 

If you think your emotionally attached to a "daily driver" as opposed to
an "investment vehicle" or a "project car" then you need to dump it
immediately.

Investment vehicles you keep in the back barn and fire their engines
up once a month and drive them around the block - really late at
night when there's no chance of meeting other traffic that might smash
into you - solely to keep the grease distributed in the bearings and
such. And it's a guarenteed coronary every time you do it. One
surefire way to know if it's an investment vehicle is if you have a separate
rider on your homeowners policy for it - if you don't, your just
fooling yourself.

Project vehicles sit on cinder blocks, jackstands, or old tree logs,
consume money, and serve the vital function of providing a conversation
piece for you and your buddies to hang over while your all polishing
off a short case. Every once in a blue moon one of these actually
changes status from project vehicle to daily driver, to the rejoicement
of the wives involved, whereupon it's immediately replaced with another
project vehicle that is even worse off than it's predicessor.

But, daily drivers are the cheap whores of AutoLand, and we all
know you never get emotionally involved in them. ;-)

Ted

 

very good advice !! a good reality check... A few weeks ago, I noticed a
coolant puddle in the driveway. My son borrowed it to do some moving and I
told him to watch for this and he said it happened once for him. Didn't
think too much about it until I started reading some post about the head
gasket. duh, I should have made the connection. If this is a blown head
gasket, it's definitely time to get 'unattached' and look for another
utility van.

thanks,
nick

 

Where was the puddle relative to the engine compartment? The 3.3 and 3.8L
engines are prone to water pump failures which are easily and cheaply fixed.

Bob

 

I replaced the water pump last summer when I changed the timing chain. I
checked all around trying to see where it was coming from. Thermostat
housing looks dry, water pump very dry, hoses look fine. That's why I'm
thinking it's coming from the overflow bottle. Doesn't overheat, no water
in the oil. Thermostat works and water is flowing. So I'm thinking the
head gasket. Would like to find another cause though, not going to spend
money on a head gasket repair. Van has 212k and there are a few other
problems that tells me it's time to let it go.

nick