2000 Jimmy will not start after battery replacement - suspect security system

You need to check for spark to the plugs.then make sure you have fuel to your injection line up top.if those are good check connection of cables.also clean your throttle bodie b carefull with the finns.still more to check but those are good starting point DO NOT SPRAY INTO THROTTLE BODIE CAN DO MORE DAMAGE & prob not pcm.let me know if still wont start

OK I now think I have eliminated the ATD being the issue. I performed the following reset: 1 Open the driver's door. 2 Press the power door-lock switch to lock all the doors, with the driver's door still open. The "SECURITY" light will come on. 3 Close the driver's door. The "SECURITY" light will go off after about 30 seconds. The system has been reset. Source: http://www.ehow.com/how_7529821_do-system-2000-gmc-jimmy.html I tested the ATD by opening the drivers side window and activating the ATD. I waited until the Security light goes off then I unlocked and opened the door. The result was the car horn started to honk and did so until I unlocked the door with the FOB key. Hence now I think this is not an issue related to the anti theft device. So where do I go from here....?

Thanks BREAK... I will do these tests and report back

my 2000Jimmy when I put the key into the ignition is turned it over it will not start it does not even make a spark I change the fuel pump its is runing i change the fill falter but the car will not start the lock button on the driver side door was clicking every time you drive it or every time you do something with the car it clicks it will not start onconnect the battery we did everything it will not start the pump is running everythings good but it just won't turn over its not making no sound when you turn ducky over it seems like its not getting enough fluid into the system that's what we think it was and now we fixed everything else your missed dunks not starting it has gas we don't know what's wrong

I tried to lock thing to where you push the button but my driver side door will not shut

As it turns out there was a huge short in the wireing harness located UNDER the abs system on the drivers side engine compartment. I was lucky the truck did not start to burn just sitting there in the driveway. I traced the problem back from the ECM fuse 2 which was not getting power at all. You may want to check ECM fuse 1 and 2 for power. If they don't have any power look for a short and check under the ABS block.