I hate to revive an old thread but im having some of these exact issues. My scenario is, 2000 xj just put a new engine in it (4.6 stroker) The engine will not start from the key, there are no reverse lights ( i know that points to NSS but bear with me) It will shut off from the key however, the key will pull out of the ignition when in the on position and running, when trying to start it with the key from inside the jeep there is nothing from the starter, no clicks nothing, the only noise when turning the key is a sound of a relay clicking on the lower passenger block. Gauges work fine (battery,oil pressure,rpm, etc) I thought if a NSS went bad the engine would still crank or click from the starter. I dont think that i missed any grounds but i may be wrong.
--1998 XJ "Mater"- RIP
2000 XJ--- 4.6 stroker. Saved from the grave- everything swapped or modded. I hate this thing :)