Okay, just tried the scanner we have at the store here (innova 3100), and it won't read my truck. What are you guys using for scanners for our cummins trucks? 

I use a Smarty...but for more than just scanning codes through. 

For awhile I had the harbor fright special that read abs also, could clear and read codes but that’s about it. 
Then went to the snappy “brick” as it’s fondly called, worked great. Still have it. 

have a newer used snappy solus now and very happy with it, very nice to have a live graph when finding issues in vehicles.

I have a snap on brick but last year got a new snap on modis  because SO now include all vehicles inc American in their software where before usa was seperate here in uk

Scope is useful at work too as it reads PWM sensors and more