The IPDM on your Nissan Titan is located over by the right hood hinge. Its near the ECM and Fuse link box and fuse & relay box. Technically is just opposite to the ECM.
It is the big black box located closet to the firewall behind the battery. You will have to remove the battery terminal to get access to it. It is held in by clips so all you need is a screwdriver to remove it.
