The truck I'm working on has the Cumins 5.9 24 valve engine. My question is about the Diagnostic Trouble Codes.

I'm scanning with the AutoEnginuity, PC based scan tool, with the enhanced Chrylser / Dodge software. I've attached the DTC Report. THIS ENGING HAS HAD THE VP44 PUMP REPLACED WITH A P7100 PUMP. I know some codes are a result of that swap.

Each of the DTC "P" codes includes a description, Status, Good Trip counts, and Starts Since Failed. Each corresponds to a code that can be found in the FSM (factory service manual) as well as many other documents.

The "Freeze Frame" information is confusing. For example, on the report I 've attached, the 3 Freeze Frames are listed as:

"Freeze Frame 1 for DTC 255"

"Freeze Frame 3 for DTC 3855"

"Freeze Frame 4 for DTC 3842"

The information contained in the Freeze Frame is clear (engine speed, oil pressure, coolant temp, etc.), but the DTCs (255, 3855, and 3842) are not defined, nor are they listed in the FSM or any other document I can find.

I am seeking any information about these codes. I assume there are many more codes, but I have been unsuccessful finding any information regarding codes in this format.

99 Dodge Cummins DTC Report 04-29-23.pdf

Are you plugged into just the port under the dash or the cummins bus by the power steering or both?

Just plugged into the OBD2 port under the dash.

My truck has no ecm plugged in and the check engine light is off and no DTCs are present which is strange not even th p1639. So the obd2 is only getting data from the pcm. The downside is the gauges don't work.

 

These trucks use a whole bag of communication standards and protocols  some have multiple protocols on the same wires.

The can bus uses both 11 bit and 29 bit I'd the vp44 is 11 bit 4 messages proprietary.  Some tuners and scan tools can request 29 bit sae1939 pid this is your best bet for real time data. 

The can bus was not extended to the obd2 port. That was required in 2008.

 

Other buses are k line iso 9141 that's the obd2 Chrysler implantation its shares with SCI which is the drb2 tool for flashing. 

 

Then there is CCD which is for the instruments and other items like radio and overhead display.

 

There was a lot of changes going on in those early years with all the manufacturers winging it on there own.

 

There are some online obd2 to sae1939 and others converters that may help. There are some pcm simulators that can wire in too. 

I'm also interested in this topic as I'm struggling to pull intelligent freeze frame data for a 1688 code. The OBDII plug-in I'm using defaults itself to "AUTO, ISO 9141-2" protocol which does allow me to read and clear the DTC. "SAE J1939 (CAN 29/250)" is also an option on this scanner. As pointed out above, there are several different communication standards which make it difficult to discern which information is coming from where and in what language.

 

I wonder if AutoEnginuity would be any help if you contacted them directly? The freeze frames themselves look very strange. I see a -58F coolant temp, 193 RPM engine speed, 7,710 RPM engine speed, 150 MPH vehicle speed, etc. Are those because of unhooked components or because the AutoEnginuity tool is not doing a good job of pulling and putting together information? Maybe they could answer that.

Agreed, some of the data is questionable at best.  Possibly due to the missing module on the missing VP44 fuel injection pump

 

I contacted AutoEnginuity first.  I provided the exact same information shown in my post.  This is the answer I received;

 

"Trouble codes listed as “not defined’ are due to the manufacturer not providing any information about them."

"I do not have any access to information that would decode the codes.  We get our information direct from Chrysler."

 

They had my description (couldn't attach the report, the tech support request form doesn't allow) word for word as it is shown in the report.  "not defined" was not mentioned, nor is is on the report.  I expected better from AutoEnginuity.  Overall I'm satisfied with the tool.  I've purchased several of the enhanced modules, but in general, the early OBD2 stuff is a little sketchy.  This '99 Dodge/Cummins, and an '02 Mazda have sometimes shown questionable data.  Later model vehicles have been great.

I was thinking about this again. Maybe you could build a little adapter. I saw some adapters that convert the round plug J1939 common on larger trucks to OBDII, but none that fit the old cummins triangle type. Finding the OBDII port is easy just make sure you get one with all 16 pins wired. The triangle shaped one is hard to find. I found one on a poportioning valve on an old junk dodge I have but the pins are smaller diameter and don't make well. Probably need to just tap into the wires.

 

Here is a diagram I made if you wanted to try it. I doubt it will display freeze frame data but It might show live data. I'm curious to know if it would show emissions readiness status and monitors.

 

Here is an example OBDII port.

 

https://www.amazon.com/XMSJSIY-Connector-Extension-Connection-Diagnostic-1/dp/B09WYZGLW3/ref=sr_1_25?crid=1K6R0TYYR2CTM&keywords=obd2+connector&qid=1685755708&s=automotive&sprefix=OBD2+CO%2Cautomotive%2C412&sr=1-25

 

 

 

 

 

   

THANKS!!  Since the problems I'm having are mostly just annoying, I've had to back-burner this project for now.  I am very interested in building this adapter to see what's available.  I just don't know when that might happen.