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Amedee
Amedee, Dodge Technician
Category: Dodge
Satisfied Customers: 25656
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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2001 durango with a 4.7. Cranks but won't start. No bus

Customer Question

2001 durango with a 4.7. Cranks but won't start. No bus error on the odometer. No trouble codes. Do have 5 volts on the feed wire. Disconnected the CKP, CSP, MAP and TPS, still have the no bus error. Not sure where to go from here.
JA: Have you checked the engine's fuel supply? And the spark plugs -- are they all working?
Customer: 1/4 tank
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: But not getting any pressure.
JA: Anything else you think the mechanic should know?
Customer: Nope
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Dodge Mechanic about your situation and then connect you two.
Submitted: 10 months ago.
Category: Dodge
Expert:  Juan Crespo replied 10 months ago.

Hi there.

Diagnosing a PCI BUS Communication failure can be a nightmare without the aid of a diagnostic port tester and a DRB-III or equivalent scan tool. Without those tools, you basically have to check all the modules on the BUS for power and ground, plus check that the BUS circuit itself is not open. Can you get access to those tools?

Customer: replied 10 months ago.
Nope. All I have is an OBDII scan tool and DVM
Expert:  Juan Crespo replied 10 months ago.

Oh well, I could only hope. What brand model is that scan tool of yours? Perhaps we can use it.

Customer: replied 10 months ago.
Make is a Centech. Don't see a model on it.
Expert:  Juan Crespo replied 10 months ago.

Centech doesn't make scan tools, just code readers, so that won't help us at all.

Let's do process of elimination; turn the ignition OFF and disconnect the ABS module under the hood; turn ignition ON. Is the NO BUS message still on? If so, then repeat with the transmission control module (TCM); and so on with all the modules on that vehicle until the NO BUS message is gone.

Components that are connected to the PCI bus circuit are as follows.

 Air Bag Control Module (ACM)
 Central Timer Module (CTM)
 Compass Mini Trip Computer (CMTC)
 Controller Anti-Lock Brake (CAB) Module
 Electro-Mechanical Instrument Cluster (EMIC)
 Heating Ventilation Air Conditioning (HVAC) Module
 Powertrain Control Module (PCM)
 Radio
 Sentry Key Immobilizer Module (SKIM)
 Transfer Case Control Module
 Transmission Control Module

If none of the modules are faulty, then you'll need to test integrity/continuity of the PCI BUS circuit (Violet/Yellow wire) from the data link connector to each and every one of those modules.

Customer: replied 10 months ago.
OMG! I don't even know what some of this stuff is. Let alone where to find it.
Expert:  Juan Crespo replied 10 months ago.

I understand. That's the way the Dodge boys designed this system - they don't want regular Dodge owners to be able to fix their own vehicles once the warranty period expires; they want them to go the dealers and spend more money there or buy new trucks.

Customer: replied 10 months ago.
What are the top three scan tools? I'm just a shade tree trying to help a friend. Not sure that I'd be able to afford one.
I've checked the TCM, ABS, ACM and CTM. All to no avail. I'll keep plugging away at the next 4 on the list.
Expert:  Juan Crespo replied 10 months ago.

Being a retired Chrysler Master Tech, the one scan tool I'm familiar with is the DRB-III. Last time I checked, those were being sold for about $6000.00; however, there was also a rental option for about $200.00 a day. Besides that, I'm not familiar with any other scan tool that has the capabilities of a DRB-III when it comes to Chrysler products.

As a suggestion to break the monotony, try checking the Violet/Yellow wire. Sometimes it is an issue with that wire what brings the BUS down.

Customer: replied 10 months ago.
It looks to me like the BCM, CMTC and EMIC are the same module. All are shown being located behind the left kick panel under the dash. Can't find the transfer case control module or the HVAC control module.
Need more information on the violet/yellow wire. Where do I find it, and how do I check it?
Expert:  Juan Crespo replied 10 months ago.

The correct name is***** or CTM - I uploaded a list of modules for your vehicle; where are you getting BCM and EMIC from?

Your vehicle might not have a transfer control module if it was not equipped with that feature at the factory. If there is one, it will be behind the instrument panel, right of the steering column.

The Violet/Yellow wire is what the PCI BUS uses for transmitting serial data. It starts at the data link connector (where you plug your code reader) and goes to each and every module.

Customer: replied 10 months ago.
I wasn't sure where some of these control modules are located. So I did an internet search and those acronyms also showed up on the CTM search.
I don't see anything to the right of the steering column, but there's so much in that area, I don't really have a clear field of view.
So how to I test the integrity of the pci bus wire?
Expert:  Juan Crespo replied 10 months ago.

At this point, I don't think I can continue working on this issue. I'll opt out so others may try. Please do not reply until another expert responds or the site will cycle this back to me.

Expert:  Amedee replied 10 months ago.

Hello and welcome! My name isCustomerand I can assist you with your question. Was the PCM replaced?

Customer: replied 10 months ago.
Not that I know of. But then I really don't have a history with the car either. A friend of mine in the church just bought it 3 weeks ago, and it quit running on her. Hasn't started since. PCM does not look new, 2 of the connectors on it are cracked. I'm trying to decide if the PCM is what's at fault before I jump through the hoops to replace it. She's currently not working and can't afford a huge repair bill right now.
Expert:  Amedee replied 10 months ago.

The PCM is the most common cause of this condition. You would just need to verify the powers and grounds going into the PCM with the key on before replacing it.

Customer: replied 10 months ago.
OK. What pins an I looking for and what voltages should be on them?
Expert:  Amedee replied 10 months ago.

Pins 2 and 22 for the power (should have full battery voltage on them with the key on.. 12.6 volts or so) then pins 31 and 32 for ground on the C1 connector at the PCM.

Expert:  Amedee replied 10 months ago.

I am glad I can help!

It has been a pleasure working with you. Please dont forget to honor your good faith deposit by rating my answer as "Excellent Service" for assisting you today.

Please let me know if you have any further questions.

Customer: replied 10 months ago.
All four leads are in the C1 connector?
And should all of the other components that Juan had me check be plugged in or not?
Expert:  Amedee replied 10 months ago.

YES, connector 1

YES, everything should be plugged in when running this test

Customer: replied 10 months ago.
Good morning. Sorry for the delay. I had a meeting to go to right away this morning. Not sure that I'm using the right connector. I've disconnected the 1st plug on the left from the PCM. Pin #2 is not in use. Pin #22 is showing -0.8 voltage. Pin #31 is not in use. Pin #32 is a ground.
Have to admit that I'm a little confused here. Juan wanted me to check the integrity of the PCI bus using continuity meter. Not sure how these pins help me to do that.
Expert:  Amedee replied 10 months ago.

Hello and sorry for the delay! The colors on the three connectors is black, gray and white. We are checking connector 1 which is the black connector. Here is the pinout chart or connector view of this black connector. You can see the color wire going into pin 2 is a light green/black wire and the wire color for pin 22 is white with red stripe. See attached diagram.

Expert:  Amedee replied 10 months ago.

Here, this one is more accurate. It is for a 4.7 liter engine.. however, the powers are still the same.

Customer: replied 10 months ago.
It does look like I was testing the wrong connector. The black on is on the right as you are facing the PCM.
This does have the 4.7 BTW.
Pin 2 does have 12 volts, pin 22 has 12 volt. 31 and 32 both appear to be grounds.
I can't get the connector apart to be able to verify color codes
I did mention to Juan that two of these connectors are cracked. Not sure if that's an issue or not.
You didn't mention whether or not this is another test? Or is this in continuation of what Juan wanted me to do.
Customer: replied 10 months ago.
Just a side note. I was unable to find the transfer case module, HVAC module and the Sentery Key Module. Searches on the Interenet were of no help in locating those. I also can not disconnect the radio without completely removing the dash. So I have not been able to complete the list that Juan sent me.
Customer: replied 10 months ago.
Sorry, one more thought. If the PCM is the cause of the "No Bus" error. Shouldn't it go away when the PCM is completely unplugged? Guess that's why I'm leaning more toward a wiring issue.
Expert:  Amedee replied 10 months ago.

Hello and sorry for the delay! I have never tried to disconnect the PCM in this situation and verified that the no BUS message goes away. That is a good question. And when we get to the bottom of the problem, please let me know for my own knowledge. My guess would be that it would not go away because without the PCM, there would not be any communication between modules so there would be NO BUS. However, my experience has been that the PCM goes bad ALL OF THE TIME on these vehicles causing this problem.

Customer: replied 10 months ago.
OK. Sure will. So what's the next step? You didn't really answer any of my questions. ;o)-
Expert:  Amedee replied 10 months ago.

You didn't mention whether or not this is another test? Or is this in continuation of what Juan wanted me to do

This is a different test

Expert:  Amedee replied 10 months ago.

I dont see any other questions above..

Customer: replied 10 months ago.
Sorry. Guess you may be as confused as I. Juan pulled out of the diagnostics when I asked how to check the integrity of the PCI bus circuit. I thought you were starting from where he left off. I also asked where the transfer case module and the SKIM are located. Those two with the radio are the only three devices that I haven't unplugged to test the "No bus" error.So what did the voltage tests on leads 2, 22, 31 and 32 tell you? We haven't gotten back to that test either.
Expert:  Amedee replied 10 months ago.

The voltage test (power and ground) check out good. This means the PCM is likley at fault.

Customer: replied 10 months ago.
why is the "no bus" error still there when the PCM is completely disconnected?
I was thinking that's why Juan was having me unplug each component one by one.
To see which one turned that error off. So I would like to continue with that thought just to be sure.
Where is the Transfer case module and SKIM located?
And how to I test the PCI bus circuit?
Expert:  Amedee replied 10 months ago.

So why is the "no bus" error still there when the PCM is completely disconnected?

I answered this question already.

My guess would be that it would not go away because without the PCM, there would not be any communication between modules so there would be NO BUS.

Expert:  Amedee replied 10 months ago.

Have you checked the voltage on the BUS circuit yet?

Customer: replied 10 months ago.
Nope. How do I check that?
Expert:  Amedee replied 10 months ago.

You need to use a lab scope and check for a 7.5 volt square wave form on pin 7 of the diagnotic connector with the key on.

Expert:  Amedee replied 10 months ago.

Pin 2. Not pin 7. Sorry.

Customer: replied 10 months ago.
I don't have a lab scope. Any other way?
Expert:  Amedee replied 10 months ago.

NO

Expert:  Amedee replied 10 months ago.

You can try using a factory scan tool..

Expert:  Amedee replied 10 months ago.

But again, it will most likley say no communication.. so you will be right back where you started.

Expert:  Amedee replied 10 months ago.

Other than that, there is no other way.

Customer: replied 10 months ago.
K. Where is the transfer case module and SKIM located?
Expert:  Amedee replied 10 months ago.

The Transmission Control Module (TCM) is located in the engine compartment on the right (passenger) side and is mounted to the radiator core support.

The SKIM is located on the right side of the steering column, below the ignition lock cylinder housing and is concealed beneath the steering column shrouds.

Customer: replied 10 months ago.
I have already checked the TCM, but Juan had the transfer case control module TCCM on the list as well.
Where is that located?
Expert:  Amedee replied 10 months ago.

Sorry about that. Here is a pic

Customer: replied 10 months ago.
I can't really picture where that might be. Is that under the hood?
Or is that the hood release under the dash?Any recommendations for buying a replacement PCM?
Expert:  Amedee replied 10 months ago.

IT is located under the dash on the drivers side

Expert:  Amedee replied 10 months ago.

The dealership is always your best bet. However, you can shop around on line to save a few bucks.

Expert:  Amedee replied 10 months ago.

Hello! It'sCustomerfrom just answer.

I am just checking in to see if you need any further assistance?

Let me know!