Do you have a multimeter and know how to use it?
With the car shutoff, check if there is any draw on the battery, if there is, you are probably shorted somewhere to your chassis. If there isn't, you're not. Simple as that.
After you've checked to make sure you're not grounded somewhere to the chassis, switch your multimeter over to measure resistance and check the wiring that goes to your guages. You should have a decently high resistance reading. If your resistance is very low (low enough to blow a fuse, without a multimeter and your guages in front of me, I couldn't tell you where than number is), then that means you probably do need new guages. I would bet it's a wiring issue and not an issue with the guages themselves, though.