When I got the truck I immediately replaced the factory radio (which had failed in the usual manner) with a nice Kenwood so I could have bluetooth cellphone CD and Mp3 play. It worked great until I didn't drive the truck for a few weeks and the battery went flat. I charged the battery and the truck works fine but the radio would not come on. It has been like that for a couple of months.. no radio. I was waiting on cooler weather to sort it out. Recently the truck had sat not driven for a few weeks and the battery was ALMOST flat when I tried to start it. I finally got it to start and on the way for its annual DMV inspection I noticed the radio was working. It has worked fine since. The only cause I can think of was the battery going almost flat. Do any of you experts know why the radio would behave that way?