NO J1850 ACTIVITY

[Don The Ham]

My LCD panel displayed the message NO J1850 ACTIVITY I kept driving and noticed the fuel gauge stopped working, the cruise control lamp remained active after leaving cruise operation, and I had to down shift the overdrive gears, when needed, by using the range switch.

At home I turned the engine off, to disconnect the car .... On restarting the dash display panel was normal, but I have not tested the over drive down shifting problem yet.

Has anyone seen this event on their MH?

[Don The Ham]

My LCD panel displayed the message NO J1850 ACTIVITY I kept driving and noticed the fuel gauge stopped working, the cruise control lamp remained active after leaving cruise operation, and I had to down shift the overdrive gears, when needed, by using the range switch.

At home I turned the engine off, to disconnect the car .... On restarting the dash display panel was normal, but I have not tested the over drive down shifting problem yet.

Has anyone seen this event on their MH?

[Horsepowerfan]

While I haven't had this happen to me I can give you an idea of what happened.

The J1850 bus is a data communications circuit used to send information to the dash gauge cluster from the engine and/or trans. computers. This information is typically vehicle speed, engine temp., oil pressure, engine speed, fuel level, etc., all the stuff needed for the gauges to display their readings and the trip computer to make its calculations. If for some reason the data circuit is open or shorted, the message you saw will appear on the dash. It basically means the dash cluster is not receiving the info. it needs from the data line.

Since it sounds like your problem is intermittent, it could be difficult to determine where the actual fault was (or is) unless the entire circuit was physically inspected including all connections and terminals related to it. It could also be an internal problem with the dash cluster or any of the computers connected to the circuit or even a software issue. It might never happen again.

I'd wait a while and see if the problem recurs and try to note anything that may be relative to when it happens. This information could help a service technician duplicate the fault and diagnose it while it's occurring. Otherwise, trying to find the problem while it's not happening could be VERY time consuming or even impossible. Sure, you could just replace part after part, but that's just not the best way to go after something like this.

Hope this helps. Jim.

[Horsepowerfan]

Oh, just thought of a few more things.

Some simple checks you could do yourself would be to inspect the chassis battery cables and connections. Make sure they're clean and tight. Also, what is the state of charge of the chassis battery? Sometimes software glitches can occur if the battery is weak. Check any of the ground connections you can find on the chassis and under the dash. Make sure they are clean and tight. And finally, if your dash flips up like mine does, just check to make sure the connections on the back of the cluster are securely plugged in.

["007"]

Nothing like having a good mechanic on the irv2 forums.

[Don The Ham]

FOLLOW-UP.
Thanks for the suggestions. I will start following wires per your recommendation and look for some loose connections around the dash panel.

Additional info, I was about 500 miles into the days travels. Home was another 100 miles with the problem active. The speedometer and tach were functioning. Fuel gauge stayed at full and reset to about 1/2 after restarting the engine.

I will let you know what I find.

[BobD]

Hey Don check the wires around your emergency brake pedal as I had a similar problem with my coach recently.
It was a chafed wire right above the emergency brake making my cluster go goofy on off etc.
Hope this helps.
BobD

[Tom N]

J1850 enters the cluster on pin 12.

-Tom
currently near Richmond, VA

[Don The Ham]

FOLLOW-UP AFTER CHECKOUT...

I inspected the wiring and connectors from the dash panel to the engine/transmission computer. I found nothing loose or frayed. Battery tested fully charged and wiring is secure. Problem may have been caused by an intermittant electrical noise on the wiring. Next week we are taking a short 100 mile trip and I will see if the "No J1850 Activity" display message comes back.

Thanks for the problem solving suggestions.

[bsellers]

We recently had a similiar problem on our MH. Our fault code was No J1587Data, also explained to me to be a communications error. A trip to Cummins and they took it to Freightliner, it was detemined during the dash install the wiring harness had been smashed and when it would touch pieces of metal as we traveled it would "short" and give the data error.