2000 Tahoe Passlock nightmare

[cocola-red]

Where is the passlock security system located in a 2000 Tahoe. I'm working on a 2000 and it was running when brought in to the shop. We exchanged engines and no it will run for 1 second then the fuel shuts off. The key that was in the switch when it was brought in is neither pass I, II,or III. I'm totaly lost. I believe the vehicle has security problems when it showed up here but was still running. The security light was on constant but the vehicle was still running.

 

[NJTahoe]

Is it just a plain metal key? or is there a black plastic on the end?

 

[NJTahoe]

Hope this helps, I've used this when my keys had to be relearned.
Relearn Procedures for GM