Resolved. I have a scangauge code Cummins doesn't recognize.

Tom/Barb wrote:
Easy things to check on a ISC the ECM will loose its ground, make sure it has a good ground, when it does not the engine drops to keep alive data.

be certain you are connected to the engine data plug. not the chassis's

Thanks again for your input Tom. Where would you recommend checking for the ground. Are you thinking a pin on a connector or something more generic like a large connector. I guess I'll have to figure out where the ECM is as well. I'll start snoopin tomorrow.