God forsaken Demon Possessed NO BUS

ItzNickTrash · May 14, 2021

I know there have been dozens of threads about this issue across every different site relative to Dodge and/or Durangos. I have carefully and thoroughly read through all of them and attempted every single possible problem solve I could find , and yet still here my truck doth sit. Yesterday I spent hours going through the whole rigamarole of testing the crankshaft, camshaft, TPS, and IAC, by unplugging each one and testing for power at the TPS to see if anyone of them stopped me from getting the 5v reading, no dice, consistent 5v reading from both the TPS and IAC (also taken with either/or both attached and detached).

At this point I decide to throw a Hail Mary by deciding to try and reset the computer through the disconnect neg terminal, hold key to start position for 30 seconds, reattach neg terminal. With the only result from that being that suddenly my key fob no longer works.

The battery is fully charged. I have disconnected, cleaner with electrical cleaner, reconnected and examined each wire and connection pin/point/etc to the point of absolute certainty that there was no problems there. I did this to literally every single electrical connection I could possibly find, but with an even closer eye on the ones most likely to be relative to the issue. So, finally today I go and find a PCM at the junkyard, it's out of a 2000 instead of an 01 but it's 4x4.5.9 R/T, so no reason for it not to work. I get home plug it in....... SAME F$+$)&! THING, crank no start, odometer blinks four times then no bus code. Also almost forgot that last night I also did the little press the odometer reset button and turn key to on trick, giving me the expected (from what I'd read all over the web) 920 921 999 codes... Sooooo what's the next move here? The plugs to the PCM look to be in immaculate condition. If there was a problem with the PCM either as far as not matching and/or having been secured (which granted I still don't fully understand the meaning of) wouldn't SOMETHING have been different? I just bought this truck and I am really in love with it so I am pretty much determined to go to whatever extreme lengths might be necessary to figure this out, if not for the sake of keeping the truck then simply because I will without a doubt go stark raving mad with all this madness continuously turning through the gears in my head....

So whatcha got guys? What's next? The only move forward I have right now to try and make is that I have a buddy with either an 01 or 03 R/T down the road who's PCM I might be able to borrow just to see what happens there. ABSOLUTELY ANY AND ALL INFORMED IDEAS AND SUGGESTIONS ARE WELCOME AT THIS TIME.

Thanks for all the help I've already gotten in past threads and my undying praise and gratitude to anyone that manages to help me actually solve this most perplexing and monstrously frustrating of mysteries.

Nick Trash

RacerX · May 15, 2021

Try your pcm's in his truck. He might be more receptive to that idea.

I'd bet the pcm is ok and the cluster is the bad unit.

Sent from my SM-N960U using Tapatalk

NumberThree · May 15, 2021

Is this all the time, or an intermittent fault that 'appears once again, seemingly out of nowhere' ?
Some 2001~2004 Dodge Durangos issues with a major harness chafing on the A-frame over time, to the point of shorting. Yours is loss of main bus, so it's like a major loss of connection rather than this "shorting-out" problem, but worth a look. Also, what is the condition of the PCM harness plug contacts?
I know you looked already, but look for any white, or green deposit on the contacts of the PCM socket pins, or the in the plug itself. Please post your findings, (pics of any damage also, as they may help in determining best method of repair). Also, a common place that especially suffers from this is at the starter connection

Since the wire insulation is made from a soy-based polymer, rodents like to eat it. And that's ALL rodent species (rats, squirrels, mice, whatever).
Some like to build nests in engine bays where it's warm for their babies, surrounded by a nice source of "food". They hide their nests under battery boxes and inside tight grill, or fender troughs, out of sight. There are youtube videos showing some fairly severe cases of this destruction. It's more common in colder environments,in wintertime.

ItzNickTrash · May 15, 2021

NumberThree said:
Is this all the time, or an intermittent fault that 'appears once again, seemingly out of nowhere' ?
Some 2001~2004 Dodge Durangos issues with a major harness chafing on the A-frame over time, to the point of shorting. Yours is loss of main bus, so it's like a major loss of connection rather than this "shorting-out" problem, but worth a look. Also, what is the condition of the PCM harness plug contacts?
I know you looked already, but look for any white, or green deposit on the contacts of the PCM socket pins, or the in the plug itself. Please post your findings, (pics of any damage also, as they may help in determining best method of repair). Also, a common place that especially suffers from this is at the starter connection

Since the wire insulation is made from a soy-based polymer, rodents like to eat it. And that's ALL rodent species (rats, squirrels, mice, whatever).
Some like to build nests in engine bays where it's warm for their babies, surrounded by a nice source of "food". They hide their nests under battery boxes and inside tight grill, or fender troughs, out of sight. There are youtube videos showing some fairly severe cases of this destruction. It's more common in colder environments,in wintertime.

I'll get to taking some pictures in a little while but for now....

It was initially intermittent and out of nowhere, it drove home from buying it just fine and the next day and then after it did it the first time it wasn't every time but still more often than not until maybe two days ago and now it's all the time. The guy I bought it from said that "it overheats sometimes with the a/c on". However I'm 99% sure that was because of the several pieces of steel he placed in the grill slots cause he though it "looked cool" 🤦‍♂️ I looked all over for any signs of damage from overheating and didn't find anything but I know that the fact that it happened makes the PCM being fried a more likely possibility.

I went through the whole engine bay from above and below the other day and sprayer every s connection I could find with electrical cleaner and the plugs and harnesses to the PCM all look to be in perfect shape. Oh, I also think I forgot to mention this in the original post that the motor is not original, he said it was a crate motor but of the exact same 5.9 model that came out of it. So the engine supposedly only has like 75,000 miles in it, the transmission even less, and the t case even less than that.

I'll go out and take some pictures in a bit for ya too though.

ItzNickTrash · May 15, 2021

RacerX said:
Try your pcm's in his truck. He might be more receptive to that idea.

I'd bet the pcm is ok and the cluster is the bad unit.

Sent from my SM-N960U using Tapatalk

Yeah he's just a flake and a half so it's really just a matter of catching him in person and doing it right then. He's impossible to get to show up anywhere at any specific time.

What do you mean by cluster?

DuRonbo · May 15, 2021

On PCI Bus cars....any individual module can bring down the Bus if it's defective. The MIC or Instrument Cluster is counted as a module also.

The PCI Communications wire going out to any module can also be a source of this issue if it's shorted to ground or voltage. In LH cars it's a single wire that's Violet with a Yellow stripe. Not sure on the Durango.

DuRonbo · May 15, 2021

Typically you use the DRB III scan tool that dealers use to communicate with and check each module. The DRB III ports into the Bus to the PCM via the OBD connector under the dash. Being the gateway to the PCI Bus...if the PCM is defective you won't be able to communicate with it or any other module on the bus.

Do you have any type of code reader or scan tool? Is it able to pull codes?

ItzNickTrash · May 15, 2021

DuRonbo said:
On PCI Bus cars....any individual module can bring down the Bus if it's defective. The MIC or Instrument Cluster is counted as a module also.

The PCI Communications wire going out to any module can also be a source of this issue if it's shorted to ground or voltage. In LH cars it's a single wire that's Violet with a Yellow stripe. Not sure on the Durango.

Oh right the instrument cluster was the last thing that I needed to check I have to pull my dash apart today anyway cuz I'm going to put a new stereo in just as a symbol of hope that I'll fix this other thing as well lol. Hopefully I'll come across something in in there today that solves the issue. We will see, and I'll be sure to post whatever it is whenever I find it

DuRonbo · May 15, 2021

If you have an OEM Radio with CD Changer that is also controlled by the PCI Bus and counts as a "Module".

Good luck.

DuRonbo · May 15, 2021

Normally for most Mopar PCI Bus vehicles the modules are as follows:

PCM
TCM
BCM
ABS
MIC (Intrument Cluster)
SRS (Air Bag)
Audio (CD Changer/Radio Presets/Memory)

ItzNickTrash · May 15, 2021

DuRonbo said:
Typically you use the DRB III scan tool that dealers use to communicate with and check each module. The DRB III ports into the Bus to the PCM via the OBD connector under the dash. Being the gateway to the PCI Bus...if the PCM is defective you won't be able to communicate with it or any other module on the bus.

Do you have any type of code reader or scan tool? Is it able to pull codes?

Yeah I have a code reader but it won't connect unless the vehicle is running. When it was still happening intermittently though it was not throwing any codes

ItzNickTrash · May 15, 2021

DuRonbo said:
If you have an OEM Radio with CD Changer that is also controlled by the PCI Bus and counts as a "Module".

Good luck.

The stereo is on that same setup? I didn't know that and the aftermarket unit that was in it when I purchased it actually was displaying some error that said something like "unit is miswired, check wiring and try again" or something close to that. So hopefully when I pull the dash off today I'll be able to find something in there that explains things. I'll be sure to post again with whatever I find.

ItzNickTrash · May 16, 2021

DuRonbo said:
If you have an OEM Radio with CD Changer that is also controlled by the PCI Bus and counts as a "Module".

Good luck.

So I was trying to put the aftermarket head unit (A Dual XDVD600) in last night with the Metra wiring harness for 74 and up Chryslers. The yellow and violet wire (which I understand to be the PCI) was already separated from the connector, what am I supposed to do with it? Ground it out? Or leave it taped off and dead? Also I read about having to be sure you get the amp Turn-On wire spliced into the ignition wire so that you will get power to the amp when the trucks on and not just when it's on AM/FM... Is that right? I also have an optical wire coming from somewhere deep inside the dash as well as 4 RCA cables that appear to be leading to the amp down in the passenger side kicker. I'm gonna pop that open today and see what the deal is with all that.

In the middle of me combing the internet and putting the stereo together last night I came across another little piece of information about there being 4 ground wires related to the PCM, one of which is supposed to be under the air filter. The first couple times the NO BUS would pop up, id kill the engine pop the negative cable off the battery terminal and just start jiggling wire connectors, but I did observe that it seemed like when I would pull the air filter in and out (to 1st try some starter fluid, and 2nd check on the PCM) that would be when it would start working again. So, I'm gonna do thorough check around there and then if need be the rest of the spots for the ground wires today with fingers crossed that's the issue.

Finally my buddy with the duplicate truck, apparently had some baby mama drama and lost all his windows so now he is alot more receptive to me trying out some parts if I need to lol. So that option is still around if it comes down to it.

DuRonbo · May 18, 2021

Do NOT ground the Violet/Yellow Stripe PCI Bus wire. Leave it taped and isolated.

DuRonbo · May 18, 2021

ItzNickTrash said:
The stereo is on that same setup? I didn't know that and the aftermarket unit that was in it when I purchased it actually was displaying some error that said something like "unit is miswired, check wiring and try again" or something close to that. So hopefully when I pull the dash off today I'll be able to find something in there that explains things. I'll be sure to post again with whatever I find.

If it has a radio head unit with a CD Changer Controller then the PCI bus is used for radio station memory presets and steering wheel audio controls along with the CD changer.

ItzNickTrash · May 18, 2021

DuRonbo said:
If it has a radio head unit with a CD Changer Controller then the PCI bus is used for radio station memory presets and steering wheel audio controls along with the CD changer.

No CD changer, no steering wheel controls, and truthfully I actually remove the antennae from all my vehicles for the same reason I don't have cable in my house so radio presets are also not a concern.

So what then? Just cap it? That won't interrupt either the 5v circuit or communication with the PCM in some kinda way?

DuRonbo · May 18, 2021

The PCI bus communicates by sending serial data pulses that vary from 0v to 5v. If the bus is grounded or shorted to 5 or 12 volts then it interferes with that communication sequence.

Like I said...it can be a module failing and pulling down the bus or one of the PCI bus wires that go to each module. If anyone of them chafes and shorts to ground or to another wire that is power or ground, it'll cause problems. The key is finding which module produces a problem and focus on it and it's wiring. If it's your Instrument Cluster drooping out....it may be the cluster itself or wiring going to it.

I know that's not much help in pin pointing what's causing the NO BUS. But it gives you a general idea of all the variables involved and how difficult it can be to diagnose without a DRB III scan tool.

DuRonbo · May 18, 2021

Chrysler made many radio head units that could control CD changers even if the vehicle didn't come with a changer.

With you saying that there's a Violet/Yellow stripe wire taped off behind the aftermarket radio tells me the PCI Bus wire was in the OEM radio wiring bundle at one point.

I'm assuming the original radio wiring connectors were hacked off and some hack job cut and splice was done or?

Is the Metra adapter harness that's in there now already there or was it something you installed?

DuRonbo · May 18, 2021

If you have a Premium Sound System with an OEM amplifier then your aftermarket radio should have an amp turn on wire. Don't know the colors on the Durango. Other Chryslers...the OEM amp turn on wire is solid Blue. Aftermarket may be Yellow. You need to refer to your Dual radio wiring to see what that is.

DuRonbo · May 18, 2021

You really need to access a wiring diagram for your year Durango for the OEM wire colors and what they relate to in the Audio system. I don't have that specific info. I'm just providing generic info for several Chrysler vehicles that share the same wiring and functions. I'm sure you can get the Durango wiring info online somewhere free.

God forsaken Demon Possessed NO BUS

ItzNickTrash

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