I have a 99 cummins that will not start. It threw a code for p0602 but the check engine light never came on. I know the code is for. The ECM not programmed right but is there a way to get it to start or test to check the ECM to see if it needs a new ECM or just a reflash? It did have a smarty programmer in it when it started doing this. We removed the smarty program from the truck

 

You should be able to ignore the ECM errors for now. The computer in the VP44 (Injector Pump) runs the engine for starting and at idle. The engine will start and idle with no input from the ECM. Here is a crazy question - what is your fuel level in the tank. The fuel level sending unit is notoriously bad in these trucks and more than one person has been caught with an empty tank when the fuel level gauge shows about a 1/4 of a tank but the tank is actually empty.
Before we get into complicated stuff, let's start with the easy stuff. Do you have fuel and do you have good batteries giving you lots of cranking speed when tyring to start?

 

Wouldn't it be great if it was just out of fuel!!!!!

 

It had 1/2 tank. We got the truck running. The was a few wires corroded from ecm that I fix.