Passlock must be disabled?

[Greatwhitenortheh]

Hey everyone,  looking for some info on passlock.  A few months ago I bought a 2004 2500hd with 6.0 and nv4500. Very familiar with these trucks, wiring seems to be the one thing I can never figure out. I've discovered that my new truck will start with any key. Doesn't matter what key as long as it slides in. Key will also pull out while running. I assume I need to change my ignition out but what really  confused me is why will it start? I've had problems with keys and security on other gmt800s. Would it be safe to assume it's been bypassed in this one? When I swap cylinder is it going to create issues? Any advice is definitely appreciated. 

[txab]

2004 doesn't care what key is in it, just one that is keyed for it. No special key needed

[Greatwhitenortheh]

Not a special key but the ignition measures the resistance of the key and is not supposed to start it. I've dealt with it in the past on other trucks. I should not be able to start it with my 4 wheeler key. My security light does not come on in the dash at all. 

[redvett]

GMT800 trucks had no chip in the key it is in the cylinder and after you change the lock tumbler assembly you will have to do a pass lock relearn.