Intermittent Engine Communications Failure - Fixed!

[MPfeif]

I've been fighting this issue since I bought my 2008 Sig (yes, Kongsberg) in 2022. Symptoms: (intermittent, and not consistent) while driving, cruise control stops working, Medallion panel display reports engine communications failure, VORAD cruise reports fault, stops working (also stops cruise), accelerator pedal non-responsive, hard shifts. Except that the cruise would not work, the other problems resolved within a few seconds. At beginning, cruise would come back after stopping coach, turning ignition off and restarting. Later, this action did not resolve cruise problems, or fault re-occured within seconds/minutes.

I pursued various J1939 monitoring options, and checked all the J1939 bus connections I could find/reach. Finally, today, I found the 3 pin Deutsch connector to the engine severely corroded. I strongly suspect this has been this way since leaving the factory, based on how difficult it was to get to the connector through the floor hatches and cutting many tie wraps. The connector was difficult to pull apart, and the silicone seal fell into my hand when the connector did release.

If you're having similar intermittent issues, consider pulling the hatches and find this connector. I'd been blaming the Kongsberg, but it turned out to be something very basic, and once identified, fairly easy to fix. Well, assuming you have the right 3 pin Deutsch connector, crimp tool and shrink wrap.

IMG_0927.HEIC

[Frank McElroy]

Thank you for posting this solution.  The basic backbone of the Kongsberg chassis multiplex system is good as long as you have good J1939 databus communication.

The weak points are 1) the MOSFET from the front CCM that feeds 5vdc to the smart wheel keypads (there is an aux 5vdc supply fix for that issue) and 2) the obsolete Eaton dash switch modules that can now be repaired and reprogrammed if you can't find a replacement in a salvage yard.  Unless hit by lightning, CCM modules rarely fail.

It's absolutely critical that on Kongsberg chassis multiplex coaches you don't let your house batteries go dead slowly while being stored or sitting at a repair shop and not plugged in.  It that happens you run the risk of burning out one or both master dash switch modules.  If you lose a master switch module, about half of your other switch modules connected to it won't work.

[Chargerman]

Good job tracking that down Mark!

[Happycarz]

You are a good sleuth to find that connector. Perseverance pays off, I’m impressed . A job well done. 

[Jim McGarvie]

We've been plagued by cruise control issues for years. It will almost never engage if the headlights are on. Once engaged, I can turn the headlights on and increase or decrease speed using the cruise control. More recently, this behavior sometimes occurs with the headlights off. I've long suspected a loose or corroded connection, but have never found anything.

Any chance our 2002 Knight with the 5.9L ISB engine has such a Deutsch connector?

[MPfeif]

Your Knight almost certainly has such a connector, but the symptoms you're describing don't quite align.

On my Signature, the cruise control functions are sent to the engine over J1939 communications. Most likely yours is hardwired from the VIP smartwheel controller to the engine.

The tie in with the headlights being on leads me to wonder if you have poor ground or possibly a high resistance connection in the 12 VDC supply. The download section has troubleshooting for the VIP smartwheels, you're in year range the smartwheels were changing to the clockspring system, so check that what you have matches the guide. I'd concentrate on the voltage measurements, and take them with the headlights on and off, and the functional tests to see if the cruise outputs are working, again with the headlights on and off.

Good luck!

 

[Jim McGarvie]

8 hours ago, MPfeif said:

Your Knight almost certainly has such a connector, but the symptoms you're describing don't quite align.

On my Signature, the cruise control functions are sent to the engine over J1939 communications. Most likely yours is hardwired from the VIP smartwheel controller to the engine.

The tie in with the headlights being on leads me to wonder if you have poor ground or possibly a high resistance connection in the 12 VDC supply. The download section has troubleshooting for the VIP smartwheels, you're in year range the smartwheels were changing to the clockspring system, so check that what you have matches the guide. I'd concentrate on the voltage measurements, and take them with the headlights on and off, and the functional tests to see if the cruise outputs are working, again with the headlights on and off.

Good luck!

 

Thanks for your response, Mark. I've long suspected a poor ground or high resistance connection, but have not been able to locate it.

Our 2002 Knight--built in 2001--does not have a smartwheel. It doesn't even have a smart driver holding the wheel.