Okay so I need to buy a PCM my motor is a 01 Tahoe 5.3 will the PCM off an 01 4.8 tahoe still work on mine?

 

No stock PCM will directly work, all need a reflash to turn off vats and other things. Since its being reflashed, what tune is in there from the start makes no difference

I use cheap s10/van pcms with the 4.3 v6 for that very reason

 

Okay so I got my pcm yesterday my question now is will my car start before I get the reflag or do I née to get it reflagged what need to be done to the pcm for the car to start and run like a champ

 

If the vats is on the car will not start and run,

 

So my car won't start at all without the reflash?

 

VATS is part of the security in the pcm and has to be disabled b4 it will start, if the vats is turned off the car will run but may run poorly until you get some kind of tune on it for your application. If you don't have a place local you can send it off and have the VATS disabled and a base tune put on it, they will want to know all the details of your build to get something to get yya started.