In my 4.6 1999 f150 I have no spark. I sent pcm away for testing and rebuild. I was told it was too bad to rebuild so they sold me a reconditioned one. Installed it and still no spark. ( the coils checked o.k.) I then replaced the cps and tested the plug at the coil. I have voltage to center hot lead but when I hook LED test light between positive battery and each of the negative leads on the plug I get a steady light even when cranking(no blinking) I just wonder if anyone out there knows whether there is any relay, fuse or other device that would affect the pcm's ability to break the negative to the coil and cause a spark???

 

Well, I don't have it running yet, but decided to go through all the fuses, relays and all that again. All fuses are fine, but for some reason I decided to take the under hood fusebox off its mounting and check all the connections underneath. When I tugged on the wire that goes from the 30 amp fuse to the pcm relay, it came right out of the relay plug. It was corroded right off the connector that connects it to the relay. Eureka! I hope