Ford Repair: 2000 Expedition wont turn over and start, starter solenoid, battery connections

Question
I have a 2000 Ford Expedition with a 4.6l V8 engine. I was driving and the radio stopped working. I stopped and turned off the engine, but now the truck won't start. When I turn the ignition switch on, all dials go to max, then return to normal, all the electronics seem to be working ok (lights, power windows, air) and the radio now works. The battery warning light also comes on. When I turn the ignition all the way to start the vehicle,  there is a loud clicking noise but the engine will not turn over. I have tried jumping the battery, but have the same result. Is this a starter or celenoid problem? My Service Engine Soon light has been on, but when previously checked, I was told it was a leak on the vaccuum on the gas cap. It didn't effect how the vehicle was driving and I've had no problems with it until now. The SUV has about 158k miles and I've had no major service or repairs in the past for it.  

Answer
The battery warning light comes on with the key ON and the engine not running, that is a normal prove out of the light.

You might have a starter failure, but some testing needs be done before replacing anything. The clicking noise is most likely the starter solenoid. Are the battery connections  clean and tight? Dirty cable connections can also cause what you describe. You should check the battery connections, and also on the firewall near the battery there are some heavy cable connections, make sure those are tight.