You may want to try and find another 2nd gen and swap IPDM's with them. It's a very quick thing to do with no tools required. See if it works.
The relay can be found at napa/parts plus. Has a different model #, etc... when I was messing with relays, the guy let me go in the back of the store and just tear into all of the relay boxes in the warehouse, found one that looks identical, plugs right into the IPDM, perfect fit... I'd tell you the part # if I knew where it was now.
You may have a bad ECM, bad ECM can be caused by a bad ground in the coil-on-plug ignition wiring. Check your grounds on the top right of your engine towards the front. Probably covered by the plastic nissan cover. Check body grounded. Bolted to the left of the battery and the right of the air box.
ECM fried on me because of a bad ground on the ignition system, crappy deal. Nissan says it was my IPDM.. Ordered a used-known-good one, ... no start (no spark).
Changed the ECM, fired right up, ran kind of rough, found the bad ground on the engine explained above, fixed.
Your truck DOES start though, mine didn't.. at all, just turned over, so it's probably got to be a bad relay in the IPDM in your case.
