Basic for all my gauges I tapped into my fuse box. You can either unbolt the box and splice into or if you want to do it real quick. Take a fuse out and put the wire in then put the fuse back in. If your looking for a 12v source, in the middle of the fuse box there will be a blue colored fuse try that. You don't have to take each fuse out to see if it will work. You can just take the wire, with the car on, and hold it to each fuse where the metel is at on it. It should lite up the light. If you don't have a good ground it won't work. If that is the case just put a wire on the battery and then check the fuse.
Good luck