can anybody tell me what that is. i'm thinking fuel pressure(fuel pump is toast). cranks but won't start.

 

I come up with ,
fuel pump relay circuit low [ or ]
fuel lift pump control circuit low
You need to see if the correct voltage & ground at computer for fuel , then see if they are correct at relay , then check at pump , remember that grounds need to be good at all these locations .
If you have the equipment , see what kind of AMPs the fuel pump is pulling , if it is getting good ground & power .
You mentioned pressure , what is it ?

 

thanks john! I called the dealership and lucky me it's under the cummins engine warranty.

 

That's the lift pump. When mine went I got that code and one other about rail pressure high. The emissions warranty will cover 100k/5 years I believe. If you bought an extended warranty and it's still in effect, your tow may be covered along with a rental.