Check Engine Light Leads to Stop Engine Light

I second the Silverleaf... gets it data from the same "brain" that the engine & tranny use...Displays all sorts of working digital gauges & will give you diagnostic codes...plugs into the J1939 port, just like the factory diagnostic computer.....

Does he have a "Message Center" ? It is the device that provides mpg, range, and lots of other things. It has a diagnostic mode.

Also Scangauge D, about $140 at Advance Auto website, will read the codes.

I had a similar experience with my MH on a trip. We had been driving for hours. It's a 300 Cummins, turned it was low on coolant. The plastic tank looked full I talked to the Cummins hotline guy and at the time he said go ahead and drive it. Oil level was good, trans level good, temp was normal, no loss of power and the coolant level looked good. I drove it on his recommendation. When I got it into the Cummins shop they added about a quart of coolant and called it good. They said the sensor is set so high that a little loss of coolant will set off an alarm. Cost me $150 for that tidbit. Worth a try.

If you have a laptop you can buy diagnostic software and a cable made by Silverleaf.
Under $300. It will tell you what's going on. You will pay a Diesel house $175 bust to pull the codes. Silverleaf tech support is good and they will help you.
I was getting check engine and bought Silverleaf. Found a bad turbo pressure sensor in a few seconds.

Now I can drive down the road and it's telling me trans temp water temp all kinds of info and if I get another check engine light I'll know why.

And you can use it in your driveway.

A good place to start is to check all battery connections at the battery. With an electronic engine, a loose connection can cause all kinds of issues.

Sure it could be something else, but this one is free and only takes a couple of minutes.

Thanks guys, he is not parked anywhere, its where we live. There is a local shop, I will find out if they can read the Cummins codes. Taking it Reno for diagnostics is just such a pain.

If he has CoachNet, he can call them for some technical help and also they may be able to send a tech out to where he is parked.

Does not have to be a Cummins shop to read the codes, but not a auto parts place. This summer I could not get into Cummins for two weeks, but local truck repair could the next day and they were able to pull the codes. Once he has the codes it's much easier to trouble shoot.
What about coolant level.

Without being able to pull the fault codes there isn't much one can do to correct. Not all the dash gauges and indicators get data from the same sensor the engine or transmission computer uses. Could be something as simple as an intermittent ground on the coolant temp sensor for the engine computer but the dash gauge is from a second sensor. The computer is going to do whatever it can to protect the engine from catastrophic damage to include leaving you stranded.

Besides calling for a tow he could contact Cummins Care at 1-800-DIESELS (1-800-343-7357).