So I just replaced my broken tachometer. Broken, as in it didn't actually read anything. Just stayed at 0.

On the new one, which worked when it was pulled from a running car, it goes to about 1500rpm when it gets power. Then, when I turn the motor on, it jumps to around 2000rpm. It drops back down to 0 when not powered.

This doesn't exactly sound right. Any thoughts?

Car is a 1997 OBS.