1998 Cherokee NO start

Someone brought me this thing to work on and its a somewhat of a fun one. From what they had told me, it died while driving down the road. Now it intermittently has a no crank problem. When I first saw what it was doing I assumed the neutral safety switch, but the only part that bugs me is that they said that it died while going down the road, in which would not be the neutral safety switch. It does not lose power to anything else so I have a hard time believing that the ignition switch is doing this. I need a wiring diagram of the starter circuit to know for sure what it is. I have searched online in several different place and no luck. If anyone has a diagram of the starter circuit, please post it for me. Or if you have seen this identical problem and know a solution, please reply.

Dying while driving down the road is a symptom of a bad crankshaft positions sensor (CPS).

I bet it's a 4.0 with 90000+ miles.

Dieing while driving down the road would be consistent with with a crank or cam position sensor, but a no crank going along with it would not be. This engine does not crank intermittently. When it does crank, it starts right up and runs perfect with plenty of power. it is a 4.0 and has well over 200,000 miles on it. I know how to diagnose this, the main problem that I have is this is a freebie and I don't want to buy a book for diagrams. I am not going to put a part on it until I definitely know exactly what is wrong. And thanks for the reply anyway. Fredjacksonsan