Hi, I have a 2003 F650 with the cummins and manual transmission. Intermittently the truck will turn over but won't start, the wait to start light doesn't come on when it acts up, and after cycling the key multiple times it comes out of it and starts. I have checked the fuses and relays related to the ecm and starting along with following the harness and ecm connections, nothing obvious there. Does anyone have experience with this? Am I looking at an ECM issue? If it's possibly a wiring issue does anyone have the schematic for the start circuit? Any help would be appreciated.

 

If it cranks, there's nothing wrong with the starter circuit.