Def. check your grounds. I had a similar problem with my 300zx couple months ago, but it was my positive battery terminal it was rusted, and it wasn't sending power to the Z, there was no click, no kind of power, my headlights, everything was dead, the car was just sitting nothing would work at first i thought it was my ground, but it was just my terminal. what you can do is get one of those light testers, ground it, and instead of touching the metal part of the postive terminal, go like 6 inches from the terminal and touch the actual wire to see if your getting power.