Okay, for fear of being considered an absolute idiot, I'm going to cry help. I have a 2000 F-250 SD with a V-10 Automatic 4x4. It has about 140k on the clock. The other day I parked it, shut it off went out later no start, just clicking. Now I have check and replaced the battery (bad) no fix, the starter relay on the right fenderwell checks good, took starter out and to a local starter repair shop. It and solinoid good. put it back in same problem. Checked ground connections and cable, again ok. I hear a relay chattering that sounds like it's either under the dash or on the other side of the firewall. Has anyone run into this problem or fixed this problem before. Any advise or suggestion would be greatly appreciated. Thank You in advance.

 

Usually when a relay chatters it's because of insufficient voltage at the relay to hold it energized. You have a poor connection somewhere in the circuit. Battery cables can have internal corrosion that cannot be seen and the only way to really check them is when under load.
There should be a junction on the left inner fender well in the engine compartment where the positive cable feeds the inside of the vehicle. It is under a plastic cover and known to become quite corroded. It might be a good idea to check this connection and clean it if necessary. Let us know how you make out.

 

I have a similar problem. Were you able to resolve this?

 

the solenoid can click,but still not work under load...are you sure it's good?