Sporadic Fault Codes….

[nikitis]

Relays were the first thing I replaced when I had my VPM issue. Was a cheap fix plus my originals were 30 years old.

 

[ewo1]

@PorchDog, Like I mentioned earlier, I know nothing about Cummins 8.3 but I do my best in trying to find you some info.

"Cummins 8.3 comm fail"

typically refers to a communication failure in the engine's electronic control system, specifically the Electronic Control Module (ECM) or Injection Control Valve (ICV). This can manifest as a variety of engine issues, including stalling, poor fuel economy, and reduced power.

Here's a more detailed breakdown:

Possible Causes:

• Transient Suppressor Failure:
  The transient suppressor helps protect the ECM from voltage spikes when the ICV closes. A failed suppressor can cause the ECM to fail or lead to other ICV issues.
• 
  
• Injection Control Valve (ICV) Issues:
  The ICV regulates fuel delivery. A faulty ICV or its related components (like the transient suppressor or pump driver circuits) can cause communication problems with the ECM.
  • Test the Transient Suppressor: Check the transient suppressor for heat and replace it if necessary.
    
    
  • ICV Resistance Test: Measure the resistance of the ICV and ensure it falls within the specified range

The Transient Suppressor absorbs the extra current created when the Injection Control Valve closes after an injection event. Without the transient suppressor, high voltage would be transmitted back into the ECM damaging the pump driver circuits and possibly the Injection Control Valve.

Amazon.com

 

[ewo1]

The transient suppressor extends from the trunk of the engine harness and is mounted with a p-clip to the engine block. It is a small copper colored cylinder with a red and black wire extending from one end. It is located just below where the injection lines connect to the fuel pump.

It is kinda hid beneath a wire bundle but the red and black wires make it easy to identify. It is about 4" long and 3/8" in diameter. On my ISC when I open the engine access door in the bedroom and lay down on the floor it is visible and accessible, if you have long arms!

Amazon.com

 

[ewo1]

I mentioned to you about the terminating resistors on the datalink...

As it turns out since the main problem was communication from the ECM to the multiplex wiring system. When poor networking is detected the J1939 system is tested for proper resistance. The resistance must be 60 ohms at the diagnostic plug in terminals but one of my mechanics got a reading of 120 ohms which means an open or faulty resistor. On a similar job I worked on one of the resistors was missing from the plug in. I think once we find the terminating resistor (one at the front and the other at the back) it will be easy to see what failed.

Source: --> Troubleshooting Cummins ISB Diesel Engine Electrical Problems

(uploaded file) Checking and Testing J1939and Diagnostic "Truck" CAN Networks

 

[ewo1]

In case anyone is wondering, Porchdog broke down again and am trying to give a helping hand, so no, I am not talking to myself....again... he is 1 mile from his storage facility and bus cranks but will not start.

Any Cummins guru's around???

If your still getting this DTC code, I am not convinced that the ABS system is involved.

1117 Power Lost Without Ignition Off Choice
1117auto Power Lost Without Ignition Off - Data Erratic, Intermittent or Incorrect
1117mar Power Lost Without Ignition Off - Data Erratic, Intermittent or Incorrect

 

[ewo1]

I'm wondering if your key switch is starting to fail ???
Cummins error code 1117 indicates a power supply issue, specifically that the power supply is lost when the ignition is on. Code 435 indicates a problem with the engine control module (ECM)'s power unit processor, possibly due to issues with the ECM's memory.

Cummins Code 1117: Power Supply Lost with Ignition On

• Possible Causes:
  
  • Faulty wiring, connectors, or fuses within the OEM power harness.
  • Issues with the battery or its power connector.
  • Problems with the key switch input circuit.
  • 
    
    • Corrupted voltage on the key switch line can also contribute to these faults.

 

[ewo1]

Porchdog,
I came across this thread that goes to talk about what your seeing on your dash ABS COMM FAIL message. the only difference is that poster has a cat motor vs cummins, but this is not the issue.

They talk about the J1939 datalink in crisis.

Abs Comm Fail - School Bus Fleet Magazine Forums

For a 2010 BB Vision (presumably a Mack Truck), the SAE J1939 data link terminating resistors are located at both ends of the data link. One resistor is in the fuse and relay center (FRC) near the VECU (Vehicle Electronic Control Unit), and the other is near the ECM (Engine Control Module). On Mack engines, the ECM houses the terminating resistor, while on Cummins engines, it's in the harness just outside the ECM.

• Location:
  The J1939 data link, also known as a data bus or CAN, has two termination resistors. One is typically found in the fuse and relay center (FRC) near the VECU, while the other is located near the ECM.

 

[desrtdog]

@ewo1 … I was getting a bit confused with all the notes above - thought you were helping multiple people because of the “porchdog” references, and 8.3 ISC, but see now that it is only me (I think) @desrtdog ….me thinks you got too many dogs in play

Anyway, appreciate all your help…here’s how things went today:

• Took the bus out around 2 pm today for a test drive as the last time I was out, had no issues on an hour drive.
• Within 5 min - literally as I turned on the main road from my storage unit, bus did the same as previous “stall” - wait to start light briefly on, flashing amber service light, power reduction, dash oil pressure indication lost.
• Pulled in to side street, bus running, grabbed codes - same 1117 and 0435 as previous.
• Cycled ignition and restarted - active codes now inactive; dropped into gear and started to go again, but same issue. Restarted again and when I put my foot on the brake bus stalled…
• When I cycled the ignition switch again, got a “comm fail” indication and the ABS light illuminated on the dash … bus would crank, but not start.

At this point, was texting/talking to @ewo1 and running through some checks with no obvious problems found…called for a tow truck (fortunately, I have roadside assistance -thank you State Farm!) and got my wife to drop the iPad by with all my manuals and wiring diagrams, then spent the next 3 hrs looking for answers that just were not coming…

Got the tow (literally less than a mile) back to storage - the driver was a wizard at backing the bus into my unit! - and there it sits …

Based on the comm fail indication, I am thinking something amiss in the J1939 system, as I cannot read any codes (including inactive ones) - or maybe that’s because the ECM did not shutdown properly(?).

On the J1939, wiring diagram has a note that says there are two terminating resistors, one of which is internal to the TCM…question is: where’s the other, and what does it even look like??
Another question is: at what point do I start pulling all of the split flex tubing off the wires, and where do I start?


(BTW - I saw the J1939 reference you have above, and also had a look at the procedure reference in post #24…)

 

[ewo1]

Porchdog,
on page 4 of the 4 page wiring diagram, on the top there is a connector labeled C808. It is a 4 wire connector with 2 white wires and 2 red wires.
The white wires are your ECM ground.
The red wires are your ECM power.

Can you locate the integrity of that connector and follow the wires to see where they go?

I can't seem to find any more info on that connector....

 

[ewo1]

Take a look at this drawing. You are correct. It seems that one resistor just might be inside the TCM.
The other one should be in the cab, either near the fuse panel or next to the mutiplexer unit.

The drawing.... you will notice that there is n ABS data link wire, positions F&G on the nine pin connector.

to the left, in red, you see the connection to the ABS and TCM.

Even though the resistors might be inside the TCM, you can still do a resistance reading, power off, and check the values.

 

[desrtdog]

Porchdog,
on page 4 of the 4 page wiring diagram, on the top there is a connector labeled C808. It is a 4 wire connector with 2 white wires and 2 red wires.
The white wires are your ECM ground.
The red wires are your ECM power.

Can you locate the integrity of that connector and follow the wires to see where they go?

I can't seem to find any more info on that connector....

That connector is the power connector to the ECM… I’ve pulled and tested all the wires on it in troubleshooting the 1117 code previously.

Take a look at this drawing. You are correct. It seems that one resistor just might be inside the TCM.
The other one should be in the cab, either near the fuse panel or next to the mutiplexer unit.

The drawing.... you will notice that there is n ABS data link wire, positions F&G on the nine pin connector.

to the left, in red, you see the connection to the ABS and TCM.

Even though the resistors might be inside the TCM, you can still do a resistance reading, power off, and check the values.

That particular drawing is for the hydraulic brake option…I have the one for the air brakes…have tracked the TCM inputs on another diagram (can’t remember which TCM pins offhand)…for the resistor in the TCM, am I correct in assuming that it would be associated with these pins?

 

[ewo1]

That connector is the power connector to the ECM… I’ve pulled and tested all the wires on it in troubleshooting the 1117 code previously.

I know your being thorough but did you open up the grounds and clean them? Would you consider temporarily bypassing those power feed wires and putting a temp wire straight from the battery to that connector, for testing purposes?

That particular drawing is for the hydraulic brake option…I have the one for the air brakes…have tracked the TCM inputs on another diagram (can’t remember which TCM pins offhand)…for the resistor in the TCM, am I correct in assuming that it would be associated with these pins?

Yes, If the TCMs are the same , which they should be, the internal resistors should be on the data pin input terminals... I will double check.

Since they are technically 2 -120 ohm resistors in parallel should you read 60 ohms when you test them at the cab/fuse side. I would have a difficult time accepting that the internal resistors went bad. If anything, maybe the cab/fuse side resistors got loose, poor contact ???

 

[ewo1]

Good read from the schoolbusfleet forum...

Problem located. One of the legs on the J1708 within the engine harness was grounding to a bracket on the LR corner of the engine thus creating a problem for the diagnostic computer to connect properly to the various modules which are all linked by this network.

Possible Data Link Issue - School Bus Fleet Magazine Forums

 

[ewo1]

The light bulb on the dash, "Comm Fail", does it indicate either engine, ABS or tranny comm fail?
Is the indicator bulb specific or general in nature?

 

[desrtdog]

The light bulb on the dash, "Comm Fail", does it indicate either engine, ABS or tranny comm fail?
Is the indicator bulb specific or general in nature?

It’s a message in the center of the instrument display - just says “comm fail” and as noted above, I can no longer read codes….reader connects, but just gives me a “No DTC Data” message when I scan…would previously I was always able to read the inactive codes, which leads me to believe there is something going on with the J1939 data link.

I’ve been reading a bit more about the terminating resistors and wondering if the other one (not in the TCM) could be out near the ECM (mounted on the front left side of the engine)…I recall seeing a plug (triangular shape) in that area when I was fiddling with the ECM connector a few weeks ago….would help if I knew what I’m looking for

Am not working on the bus today, but will check that out when I go back up there. I looked round under the dash at the wiring and just did not see anything that looked like a terminated connector…also, do not see any indications of said resistors on yet he wiring schematics…

Lastly (for now), am I correct I assuming that the only modules interfacing with the J1939 are the ECM, TCM, and ABS modules?

 

[ewo1]

Post #12 of the thread, there are pics of what terminating resistor look like, International.

Check Trans Light

Hey everyone new to the site but have a total of 4 skoolies :ermm:. I have a 2003 IC bus with a DT466E and a 2000 series transmission. i have this bus gutted and all open so i used it for a media room a couple weeks ago on a family camp out i took two buses there and the IC was where the kids...

www.skoolie.net

 

[desrtdog]

That pic appears to be a connector…

 

[ewo1]

That pic appears to be a connector…

ok, look at the pics in post #21 in this next thread.

TCM to ECU communication issues t444e/Allison 2000

CadillacKid, that’s useful information on the inhibit modes and I’ll definitely bring it up to the mechanic… prob just have him read your post so I don’t misinterpret it. Ewo1, so I only tested the backbone from the diagnostic plug. From Can(+) to Can(-) or D to C, I got about 62 ohms with my...

www.skoolie.net

For reference only, this is what a cummins marine resistor looks like.

Cummins Marine Terminating Resistor (120 Ohm)

Cummins Marine SmartCraft Terminating Resistor CAN 2

www.sbmar.com

Post #9 of this RV forum thread has a pic of another type of Cummins resistor.

Can't find terminating resistor - iRV2 Forums

Can anyone help me find the terminating resistor on the engine end of a 2007 XC-R freightliner chassis W/ OM 926 la engine. I'm not getting any help at all from freightliner. I'm getting no resistance

www.irv2.com

 

[ewo1]

Lastly (for now), am I correct I assuming that the only modules interfacing with the J1939 are the ECM, TCM, and ABS modules?

From what i can see, so far, on the wiring diagrams, I do not see the datalink going to the multiplexer so I guess the answer to your question would be yes ECM,TCM and ABS.

Page 5, text

Termination Resistors
A J1939 network requires a 120 Ohm termination resistor at each end of the backbone (Figure R–3). With all controllers powered off and both termination resistors in place, an ohmmeter should read 60 Ohms across terminals A and B of the 3-way connector (Figure R–5), or Terminals C and D of the 9-way connector (Figure R–6). The test can be performed with controllers connected to the backbone because the impedance at the controllers is much higher than 60 Ohms and therefore does not affect the reading. A measurement of 120 Ohms typically indicates that either one of the two termination resistors is not in place, or there is an open somewhere in the backbone of the network. A measurement of 0 (zero) Ohms indicates that there is a short between the CAN high and CAN low wires of the network. The short may be in the backbone itself, or in one of the stubs connecting it to a controller.

 

[desrtdog]

At the bus yesterday evening for an hour or so…this what I got through:

1. Disconnected the batteries then measured the resistance of the J1939 network across terminals C & D of the diagnostics plug: 48 ohms initially but slowly climbing - like in 0.1 ohm increments at a faucet drip pace…did not measure long enough to see if it would get to 60, but this does not seem right. IMO the resistance should be 60 (or nearly there) immediately. Doing some back calculating, this would suggest that one of the terminating resistors is at ~ 80 ohms…
2. Reconnected the battery, then checked voltage at C808 (the 4-pin power connector at the ECM): 12.7v; also checked the voltage at pin 45 of the ECM OEM connector (this is fed from the ECM ignition relay via a 5 amp fuse): also 12.7v with ignition “on”.
3. Still have the ABS light illuminated when ignition on, as well as the red STOP notification and “!” In the display, or the “Comm Fail” message - see below -
   
   
   which I can toggle between with the selector bottom on the right side stalk…
4. Looked all over for the terminating resistor - under the dash, behind the instrument cluster, in the electrical panel below the driver’s window…nothing… Found a triangular connector that looked like it could be one next to the ECM on the front left of the engine, but it is just capped…

After reading a bit last night, went back this morning and grabbed the active and inactive fault codes from the ABS module using the “blink codes” diagnostic switch…currently showing 5 active codes: first one is related to the J1939 Retarder - code 11/2 - basically loss of comms. The other 4 are related to the 4 wheel speed sensors (open or shorted), which if I had to guess are a result of the first. On the inactive side, there is an 11/1 code (J1939 serial link loss of comms), a 12/6 code related to the ABS indicator light circuit fault, 4 codes related to the pressure modulation valves (common open circuit) and a battery open circuit fault.

Seems like I'm dealing with a comms issue on the J1939, but all still a mystery. Next steps are to check the terminating resistor inside the TCM as well as find the elusive other one…also will pull apart the connectors at the PDU and, I guess, start unwrapping the wire harness inside…

Anyone else have any ideas?