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, but I have been unsuccessful finding any information regarding codes in this format.

 

How does it run

 

It runs really well since the pump swap. It has several INTERMITTENT issues including tachometer, cruise control, and Banks Brake. It had these same issues before the pump swap. The P7100 was installed when the VP44 failed mechanically, the intermittent problems were occurring before and after the swap.

At this point, I'm really curious about the format of the DTC codes relating to the Freeze Frames. I'm working through the CKP, CMP, harness, CAN and Powertrain module (PCM) looking for the root cause of the intermittent issues.

Another curiosity is the 2 codes from the Transmission Control mod as shown on the report. This truck has a 5 speed manual trans and (as far as I know) no TCM. The APPS (Accelerator Pedal Pos, often called TPS) is still in place as it is necessary for the Cruise Control to work. I believe it inputs directly to the PCM

 

I don't have a clue on solving the problems, but I'll be watching this thread with interest to increase my meager knowledge......Ben

 

Good on you. Lots to learn from these discussions. I'm a retired tech, auto and heavy equipment, with over 40 years of experience. Still learning.

 

Me too, less the heavy equipment...Learning is a lifetime commitment for me...To do otherwise is to wither and die......Ben

 

Not sure what year you are working on, but that sounds like the classic symptoms of a cam position sensor, or crankshaft position sensor going bad. 2nd gens have two computers, plus the VP44 internal controller. The PCM is a fairly normal Dodge computer, also used in the gas Rams, and pretty much runs everything on the truck except the engine. That's the job of the Cummins ECM and the VP44 controller. In a gas Ram, the PCM also runs the engine.

The VP44 has an internal position sensor, and is able to function on it's own without the signals from the cam/crank sensor via the Cummins ECM. This is why the diesel Rams will stay running when the cam/crank sensor goes bad. Gas engine Rams will shut down entirely as the PCM needs that signal to know when to fire the spark plugs and fuel injectors. In the diesel Rams, the PCM thinks the truck is not running with the loss of the cam/crank sensor and shuts off the alternator, A/C compressor, and cruise control. Since the PCM also drives the instrument panel, the tach will drop to zero as well.

I mention the both the cam and cranks sensors. I don't recall which way it is, but early 24 valve engines had one, and the late 24 valve engines had the other.

 

My engine has both CMP & CKP (Cam & Crank sensors). It's my understanding that early 24 valve had both, later had only the CMP (cam). However, both have been replaced on this engine. The Banks Brake is not dependent on either, and it isn't controlled by the PCM or the CAN bus. However it does require a signal from the APPS (TPS), and the APPS inputs to the PCM which controls Cruise and Tach. My current thinking is that somehow the APPS may be the root cause of the intermittent problems.

BUT, my original question still stands. What are the DTCs, 255, 3855, & 3842, that are listed for the Freeze Frame data in the attached DTC report?

Help regarding the intermittent problems and information regarding the unidentified DTCs is appreciated very much.