2001 Cadillac Catera It Will Not Turn Off

Can't say I've run into a situation like this. Review of some schematics would suggest maybe a sticking engine controls power relay, a faulty ignition switch, or faulty ecm. The easiest would be trying to swap the engine controls relay with one identical in the underhood fuse box, or tap on it. It is labeled as K43, thats all I know. Pin 31 of ecm connector C2 is controls power relay control, the ecm grounds this wire. It is a brown/gray wire. If this don't work, I would try an ignition switch.

Thanks for your help, now I've got some where to look, thanks for responding so quickly, I will let you know when I find out.