Left to work in the morning,no problem. Truck did not want to crank over in the afternoon. The lights on the dash were very dim. I tried cranking and all I heard was a click noise. I then tried jumping it with a big dump truck and nothing. I checked connections and all looked clean. I had someone move the relay/fuse block and it seemed like the dash lights flickered slightly. I then got the dash lights to be pretty bright and then cranked it and the same, just the relay clicking and the lights dimmed again. Could it be a relay? I did smack the starter some and then decided to push start it and it fired right up. As I was driving about 40mph or so, I turned off engine and cranked it, and nothing again. I pop started it while I was coasting and it turned on again. what to check? Anyone ever have this problem? What was it?