remove backing by pulling up on the bottom left section. There is a little tab indentation there. Once opened remove the battery and there the sim card is located behind it. Once there pull back the metal section to the left and up and it'll pop up. replace card and follow instructions in reverse to put back together! Best, Tim

Hey Jomozolo, I had this problem before and did just as you did. I ended up following the wires everywhere and testing each one and found there was a bad ground (on my fuel pump if memory serves me right) that was absolutly draining my battery! After fixing this, my truck ran just fine. It could also be some bad corrsion on a connector if your from the Northern states. I hope this helps out! -Arch