It's only there if you pull the lever toward you. If you only push it up then it won't happen.

 

i dont think they shut off completely, very close to it, but i have seen my instantaneous shoot up to 99 under a couple of conditions, and since the computer doesnt measure fuel flow rate, it calculates instant mpg based on engine RPM, engine load and vehicle speed(iirc) so it is not really any more than a reference point, it is NOT the 100% accurate 'word of god' that some consider it to be.

also it is possible to push hard enough up on the gear shift to pop it around the reverse block, i wouldnt chance it.

 

I think your right shrps, only the new diesel will completely shut off, at least the duramax will.

 

It won't shut off but it will drop the RPM's down to about 500, or idle speed. And I tried to accidentally go into reverse while in drive with the brake on and you really have to hit it hard to get it to go into reverse. When it did go, the lever was pulled forward a little.

 

well guys, just wanted to say thanks for all the replies!