After it was turned off it did not start again?

Thanks Joe, it has spark. I can hotwire the fuel pump and it will run so the fuel pump works but the relay in the under-hood fuse box is not getting ground. Several relays are not getting ground. Weirdly, the ground is turned on and fed by the PCM. My understanding is that this is how PATS works, it shuts off the ground. Yes, I have checked the inertia switch. The intermittent part is what gets me and no trouble codes and the fact it started acting up when driving. I will check the crankshaft position sensor. Is that common to be intermittent when it goes out?

Thanks Joe. I haven't tried starter fluid but I can jumper the fuel pump to hotwire it and the truck will start. So, I’m getting spark. I've checked and rechecked the PCM ground. I feel like it's down to the PCM going bad or something in the wiring harness or the fuse/relay box itself. Is there a way to “open up” the fuse box under hood? It looks pretty sealed and one-piece plastic. I would like to get into it and trace the grounds and look for anything wrong before swapping the PCM and having it reprogrammed to pats.

Yes, electrical is not my favorite to chase down especially when it is intermittent. And yes, I have positive power to the relays. I should say that this is a project vehicle, and I stopped my diagnosis when I discovered the PCM controlled the relays by turning on the ground. That was new to me, and it looked like I would need to start unwrapping the wiring harness to trace the ground distribution wires and connections. I don't have time this weekend to dive back into it, but I am trying to get sage advice from more experienced people to help me formulate a logical game plan when I do have time to go back to it. I was hoping this was common and there was a known culprit and remedy. But it sounds like I need to just continue with the logical progression through the harness. Do you know if there is a way to open up the relay box more and get to the bottom of it where all the wires come in?

Thanks Joe, from your earlier diagrams it looks like I need to look at pin 103 with a black/white wire? Number 570 in the diagram? Is that your understanding of the ground to the relays that is controlled by the PCM?

Joe, where do you get your wiring diagrams? Haynes and Chilton manuals don't have the detail they used to. I have tried a couple subscription services but wasn't satisfied. What do you recommend?

Thanks Joe,

It has been over 20 years since I ran an automotive shop and we had AllData for the shop. I didn't use it much as a manager and I remember it being too expensive for personal use but I see now they have DIY for the home user, but it is single vehicle specific. Still not a bad cost if you have a long project and want a one or even three-year subscription. I haven't used Mitchell in a very long time, used to go to the library in high school to look at the manuals there and get answers and copy diagrams. I will look at Prodemand. I did find a 2000 4.0 OHV PCM PIN Out online. I assume 2001 would be the same. And how different is the SOHC engine as far as PCM and wiring harness? Besides worrying about PATS, the PCM's wouldn't be interchangeable from OHV to SOHC would they? How about the wiring harness? Is the harness specific to the engine? Different sensors? I ask because I have a SOHC parts car available to me if anything were compatible with my OHV.