infamous "no bus" problem

Ok, here's the deal:
1999 Durango, v8, 64k miles
Intermittent engine + guage failure; odometer reads "no bus". The fix is, I go and press on each of the three PCM connectors and at some
point the whole thing comes back to life. No heat correlation, and it's really easy to get it going again. When this happens, the ODB codes get reset, but there aren't any codes being recorded (I know the codes are being reset because some of the tests that only complete once you've driven a while show as incomplete again after the error occurs).
Finally - it's a friend's backup car but her parents are coming to town and this just started happening. I'd like to save her a bill at the dealers. Is this definately the PCM (and therefore covered under the 8/80k warranty)? I pulled all the connectors and sprayed everything down with electronic cleaner; didn't really help anything.
Sometimes, the jostling of the engine trying to start actually fixes it.
Any help terribly appreciated!
elijah
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Tune up with new spark plugs and distribution cap. I wonder when was last time u guys had ur durango tuned up? Its low mile and u said somtimes jostling around with engine makes it work.
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What's that supposed to do to a loose connection at the PCM?
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MMmmmm......check for corrosion on those pins. Take the
connectors apart and have a look inside. Moisture...corrosion
or something along those lines possibly.
--
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Laszlo Almasi
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There was a recall on '03 Rams to add O-rings to the PCM connectors - you may want to check and see if anything similar was released for the Durango's.
Even if not, I'd put a bit of dielectric grease across all the pins, and might even go so far as to run a tiny bead of silicone around the outside of the plugs, where they meet with the receptacles, to try and seal out any moisture.
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Tom Lawrence wrote:

Ooooh - dielectric grease! I like that idea.
We live in an *extremely* humid climate - the wet side of the Big Island of Hawaii. 180+ inches a year of rain in places, and continual heat and moisture. Like I said, the connectors *looked* good - but anything to keep the connections good in there. The connections are *right* under the place where the lid comes over the fenders, a prime place for water to splash in.
thanks for the ideas!
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ok, let me follow this up a little.
*if* I lube the hell out of it with grease, and silicon it, and I'm still seeing the same problem - can anyone say "that's probably the PCM, then" or "you should replace the harness" or anything to guide me further?
thanks, elijah
snipped-for-privacy@gmail.com wrote:

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Of course not. The computer is telling you that it is losing communication with the PCM. It isn't telling you the plugs you are messing with are the fault. It doesn't know that. It could be the cable itself or even the connector on the other end of the cable. You have to determine the rest. If you are at a loss, bring it to a dealer. Steve
wrote:

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um; I asked -
"*if* I do what was suggested, and I'm still seeing the same problem, can anyone guide me further?"
you replied, "Of course not."
by "of course not" - are you saying that IF cleaning up the plugs doesn't fix the problem, AND if I can still consistently get the PCM to come back online by pushing on the plug toward the PCM (which is how I fix it now) - are you saying that if that's the case, no-one can give any advice to further guide my repair efforts?
seems a little extreme; I bet there's more knowledge on this board then that reply implies.
elijah
Steve Lusardi wrote:

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It is not possible to tell you how to think. As much as we may wish to help, we are not there, you are. You know there is an intermittent connection, but you don't know where. It could be at either end of the cable. It may be a bad wire crimp on one of the pins in either of the two plugs. You may have to take an ohm meter and wring out the cable wire by wire wriggling the harness in all directions or other steps. These are very basic trouble shooting skills. If you don't have them in your tool bag, I seriously suggest you bring the vhicle to a dealer before you either hurt yourself or the vehicle getting up to speed. Steve
wrote:

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==============Steve Lusardi wrote to the OP in message:

<<snipped>>
very basic trouble

(BECAUSE.....)
======================== "IF".....the symptom is EXACTLY as you just stated it.......... and the cure is EXACTLY as YOU stated it........
then..........
strap a wire tie around it and go git drunk and .......
fergittttttttttaboutitttttttt
or......... act like a well-trained ASE Certified Master AutoTech........
and.........
overthink it to death!!
:)
~:~ MarshMonster ~Zipties.......Gawds gift to the YardBird~ ~:~
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yar. that's a good answer, there... the thing is, I'm returning the truck to my friend when I'm done "fixing" it and I'd like to feel like it's fixed. hard to say, tho.
I guess one question would be - *is* there an argument for the PCM having a hairline crack or any of that business? since it's still under warranty it would be nice to just make it the dealer's problem. However, it's not a heat-sensitive issue; sometimes it happens at first startup after sitting all night.
Oh well, I caulked and greased it and it hasn't happened lately.
thanks, all!
elijah
Marsh Monster wrote:

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============ snipped-for-privacy@gmail.com wrote:

========
lmao
well.......there's always that option.
rotflmao
~:~ marsh ~sips his crownroyal......fixed is fixed if it's fixed and it's fixed if the customer thinks it's fixed and the customers fix is cost effective~ ~:~
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On 24 Nov 2006 17:29:08 -0800, snipped-for-privacy@gmail.com wrote:

If you can demonstrate to the dealer that it fails and the "no bus" condition supported by your own documentation of others with identical problems from reports on Internet sites tracking vehicle failures, fixing with the PCM one would think they would give you the benefit of the doubt. I might even use the approach like you did here: as if they already knew about "The old NO BUS problem" if I were you, since I would expect that they have seen it a few times no matter if they admitted it or not....
The only time I have known of anyone fixing the no bus without the pcm being replaced was once a guy reported that the dealer "re flashed" (reloaded the control software) the pcm. My money still says PCM, let us know Elijah, good luck and drive very cautiously till you get it fixed one way or another. best regards, Joe
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snipped-for-privacy@gmail.com wrote:

"electronic cleaner" ???!!!
What the heck is it? Some of that stuff will do more harm than good.
JAM
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On 21 Nov 2006 13:31:12 -0800, snipped-for-privacy@gmail.com wrote:

It sounds like you are traveling down that same road in diagnosing the problem as I did a while ago. First, it is my understanding that the problem is within the computer (for most if not all of the ones that were analyzed beyond replacing the pcm, anyway), more specifically what happens is that over time with hundreds of on/off cycles of the rig the circuit board will develop microscopic cracks in the printed circuit land patterns causing the electrical connection to open or at least become very poor quality after the engine compartment has been at operating temp for some time and there has been lack of airflow in there, like you went to the store a couple miles away, turned off the rig went in and came out 5-10 minutes later got in the rig started up and was fine for about a half of a block, the "no bus", the rig stalls and won't fire but will turn the motor over. NOW, you probably pop the hood and go out and start "checking stuff out" under there. (Meanwhile the heat is escaping from the engine area...) You likely have figured out if it has happened for a while that you don't need to try to start the engine rather just cycle the key from off to on and watch the trip odometer. If it hasn't reset itself (yet) it will flash three times and display "no bus", when it is ready to start again when the key is cycled the odometer display reads normally. With my rig initially it would cool itself off if I opened the hood for 3-5 minutes, with it closed it was a little longer but not a lot. Over time it will likely become longer, given the nature of the problem, mine did and my rig didn't develop the issue until I had driven it for almost a year. The pcm is considered to be part of the emissions control systems so you should get a replacement at no charge(they are warranted for 8 years I believe) other than the cost of one or more service appointments while they "prove" it to themselves, unless you simply demand that it be replaced and use printouts of the 150 or so identical problems logged in Allpar or other problem tracking sites. I just put in a used PCM since I didn't have the time to sit there while they checked it out and also didn't have another vehicle to use, cost me about 120$ been fine since. Also sometimes I would get a error message if I ran the dashboard diagnostic when the "no bus" went away, before doing anything else, it reads out in the same display. As I recall the code was 192X, as well as 1999. However, many if not most of the time it showed no other errors, and as you indicated it resets the PCM reset able errors as well. I was told that I needed to have the pcm reprogrammed to show my rigs VIN number, which Daimler Chrysler of course wanted to soak me fifty bucks for, so I may do it one day but it has been running fine for almost a year with no perceivable differences. I did order the exact PCM number for the way mine is configured which didn't hurt either I suppose. The no bus problem IMHO is one of the most dangerous failures since it is random and it literally disables the vehicle immediately, if you are in the fast lane on a freeway, or in the middle of an intersection trying to turn it can get VERY exciting, I almost crashed several times in similar situations attempting to get off the roadway. It seemed to help a little if I left the hood wit the main latch open only held by the safety latch, not a safe practice either but if it avoids being completely disabled it is worth it, at least as a temporary measure. The reason you haven't yet associated the problem to heat is that the PCM seems to lag behind the apparent engine bay heat and it is in the flow of air from in front of the airbox which might keep it a bit cooler. In the winter here in Oregon my rig would almost never fail, but in summer when it got over 80 degrees you had better keep air moving through the engine and if you stop raise the hood slightly until you get back to the vehicle or expect a no bus within 3-5 minutes of starting off down the road again. It does get worse over time though if mine was any indication of the failure mode, with winter approaching it might appear to go away, but trust me it is still in there. Good luck and I hope I have helped a little anyway. Now, if I could figure out a way to inexpensively fix my next legendary Durango design bug: The "rocking horse" drivers side electric seat, where the motorized part separates from the seat base bolted to the cab floor, of course none of you Durango drivers ever heard of that one did you? Best regards, Joe
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================Joe Brophy wrote in an essay:
<<snip>>

. The pcm is considered to be part of the emissions

<<snip>>
The no bus problem IMHO is one

================= Considering this last Humble Opinion of........"Yours"....
then, as YOU stated, with numerous documentation and various assundried reports of this being a "Known" problem..........
(and of course, you seemingly being of sound logic...chuckle,chuckle)
expain to me, a simpleton........
EXACTLY........
what logic was used...........
to decide........
to install.....
a "USED"...computer.......
for $120.....
in order to "fix" the symptom that is know to exist in these computers.......
I mean....... you already had a "used" computer. One with the documented defect. Now..you have purchased another one. With the documented defect, allbeit the symptom has'nt shown yet.
have'nt you?
oh....... it came out of a "low mileage" vehical.......mmmmmmmm
^ ^ o o L O
Before you git started with me, let me say.......I promote the use of "recycled" automotive parts.
I understand.....yer truck is fixed.
I know yer a happy camper.
but.......
you spent $120 for a computer... that MAY have cracks in it. (according to your post)
so..... I am proud of your ability to diagnose and repair.
I am glad for you....your truck IS fixed.
however, I honestly don't understand the logic.... especially considering the fact..... that YOU....stated.......
it was a warrantied part, but you didn't feel like waiting???????
oh yeah....... and the parts I snipped........ lol.
~:~ MarshMonster ~takes a toke, sips his mushroom tea.....and confounds himself~ ~:~
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Sorry to have caused so much confusion. My "logic" in replacing the computer with a used one consisted of the following: 1) My previous experiences with Daimler/Chrysler with intermittent was that it would take at least one if not several service appointments to convince themselves of the validity of the diagnosis, I didn't currently have alternative transportation without renting another vehicle, therefore was not willing to wait through multiple appointments at the dealer. 2) I had already tried to convince the service manager to just swap out mine for a new one, without the cost of a service appointment(s), to no avail. 3) Without going through the appointment process they wouldn't be abler to charge it off as an emissions failure since they didn't prove it to themselves, so from the dealer a new PCM was somewhere in the 450$ range, and since there was not any difference (design wise, nothing I could find anyway) a new one would be just as likely to fail as a used one. The only other viable alternative was a PCM from Mopar Performance, which actually cost about 100$ less but it required that you burn only premium gas, which I didn't want to be forced to do. 4) I had already installed all the engine compartment cooling "fixes", like the viper fan which was eventually standard on the Gen 1 as the mechanical fan. I installed a 180 degree thermostat (recommended by mopar performance) and enlarged the fresh air intake to the engine compartment on the passenger side, in addition to removing the under hood insulation (It was sagging anyway). (I know I didn't mention these changes in my earlier post, but they were as a result of the path taken to determine the root cause of the problem, ending in the PCM being replaced) At the time the issues were just beginning to appear in other Durangos so there was not hardly anything available from other owners to simplify the diagnosis. Most were in a similar process trying to determine what THEIR problem was too.
So, in summary: Used vs new PCM, I didn't see any difference in their reliability, therefore, I had no desire to pay for the new cost of a PCM (either with $$ or my time for multiple service appointments), a half hour of my time and 120$ seemed to be a more reasonable approach. Plus the engine compartment now had all factory or mopar performance recommended/mandated cooling enhancements that were available so I was hoping that the heat had been reduced enough to prevent future failure of the PCM for the same cause, which is holding true thus far anyway. I hope I have not added to the confusion and maybe even reduced it a bit...regards, Joe.
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Joe Brophy wrote:

============== Joe, I wasn't confused.
I jest found absolutely no grounds in your post to support installing a "used" pcm that, based on your statements, very likely has the precursers to the symptom you described. Again, based your words, your symptoms, and your explanation of what causes the failure.
Unless.......the vehical had 0 miles on it........ then.......moot point.
Here's my view... based on your original reply and the last reply.....
You didn't want to pay to rent a car.
You didn't want to expend the time to have a diagnosis.
You purchased a used pcm....which by all accounts as you've described them, may have the same cracks in the circuit board. (based on the words you typed, this is a KNOWN problem) (so...a USED pcm likely has the problem)
You were aware that a pcm could be installed for FREE under warranty.
You payed for .......air induct upgrades You payed for........cooling fan upgrades You payed for........a USED pcm You payed for.........ALL that goes along with that. (sealants, solvents, coolant....and such)
now...........
how much was that rental car....... and the FREE NEW.......pcm?? the one without the possible cracks.
What was the Federal Mandated warranty on the new one? How about the Used one?
not try'n to argue...... jest ain't logical in my view.
anywhoooooo, as i said...i'm glad yer truck is fixed, that your happy with the way it worked out, and that YOU BELIEVE it was the best overall repair decision.
because....the customer is ALWAYS rite.......
I would be interested in the overall time you have invested in the addon upgrades, the diagnostics, and overall time output for the repair, as well as the TOTAL cost of all the repairs.......solvents, sealers, testers, tools, ...and your take on how much you actually saved in time and money.
you leave out the skint knuckles and bloody fangers.... i understand........that's a given.
You could just reply..........
I'm cheap dammitgumby....and i like work'n on my truck.
now that........
i could understand.
~:~ marsh ~pours joe a crown n coke~ ~:~
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