the reason they come on with the ignition is because you wired them to a FUSE... a fuse has constant power when the car is on. you need to take off the headlight switch, and in the back of the headlight switch, there are two orange wires with blue stripes. One of them is the power for the dimmer. Tap into one of the two wires at a time and see which one allows for the dimmer on the gauges. However, both of those orange wires will work for the gauges power. Tapping into one of those wires will allow the gauges only to be on when the headlight switch is turned on.