No J1939 Activity error

[Stretchrcr]

Got a bit of a challenge going on so I’m checking to see if anyone has any suggestions. Motorhome is a 2006 Bounder on a W22 chassis with an Alison transmission.

I’m on a trip from SoCal to OR and currently stuck in Patterson, CA. On the road last night and got this error after hitting a bump in the road. The error flashed I think, and the transmission downshifted but went back to normal in a second or two. I stopped but everything was working normally to I kept driving. 100 miles or so later it did it again but this time the error flashed on and off every few seconds. I got off the freeway and did some troubleshooting on side streets.

When I got the error the trans would shift incorrectly or get stuck in a gear. I checked battery connections and grounds and did some test drives. If I restarted the motorhome, it would shift normally for a few seconds and then the error and symptoms would return.

Thinking it was probably a wire that rubbed through somewhere between the trans and the TCM I got under it and chased the wiring the best I could but didn’t find anything. After multiple test drives the error now doesn’t go away if I restart the rig. Still think it’s wiring since each time it seemed like the error came back when I hit a bump. Now I’m guessing the wire is either completely severed or grounded since the error won’t go away now.

I’m thinking I will test continuity from the TCM to the plug on the trans next but there are about 80 wires in the TCM plug and I can’t find a wiring diagram that goes into that level of detail.

It’s Sunday so I haven’t been able to find any shops in the area that could help. I’ll start calling in the morning unless I find something soon.

Any suggestions or ideas?

Thanks,
Brent

[CJ7365]

Kevin is a great Workhorse resource, he was banned here because he was accused of trying to get subscribers which is NOT true at all.

He is very knowledgeable and will even talk to you on the phone.

His number is posted on his YouTube channel


https://youtu.be/Y_JpY6cOm-8?si=XEUEDXLAWKT3GXWk

[SafariBen]

Just the description in that video explained more than I can, and I'll probably butcher the basic facts here, but I'd follow the advice in the video, and lots of results for J1939 searches. J9139 is a canbus standard, so the devices are talking over TWO wires, not all the rest of the wires going to the various transmission sensors, you can ignore most of the wires for now if you can figure out the important ones to look for, and that comes after power and ground.

[Stretchrcr]

Hi everyone,
Thought I would share what I found on this adventure.
I got the rig to Mello Transmission in Modesto. Can't say enough about the team there. They really went above and beyond to get me back on the road. They quickly determined that my TCM had failed. Not great news, but at least I knew what needed to be replaced. The challenge is TCM's for these years can be hard to get. The one's for the 5 speed 05 and earlier seem to be available, but for 06 and probably some of the following years they are hard to find and there are issues with who can program them. We had a GM dealer send us one but they couldn't program it. Then once it arrived, it couldn't be programed through the Allison software or another third party resource either. Seems like there's been changes over the years in the relationship between GM, Allison, and Workhorse and there are some real gaps that haven't been corrected. We finally got in touch with PCM Performance. They were well aware of my situation and said they could send me a new pre-preprogramed TCM. It wasn't cheap, but at least it was available. Once it arrived, we plugged it in and everything worked as it should.