i think theres a good chance the problem is between the battery and the under hood fuse box. did you clean the connections at the battery terminals ? just recently my truck did this to me on the trail, same symptoms. first thing i did was clean the connection at the negative terminal since that seems to be the spot whenever i have a starting issue but no go that didnt work. i thought my battery was done till i saw my head lights worked fine. i cleaned the connections at the positive terminal and it fired right up. simple stuff first.