Just connect up a voltmeter and drive around and that should tell you everything you need to know. Personally, I prefer to have one perminently installed in the car:
It requires 4 wires to wire up the voltmeter. Two for the light bulb (goes on dimmer circuit) and two more for the power and ground (respectively). I simply removed my radio adapter harness and added it to that (with a disconnect, of course). All the circuits you need are there. However if you are good at splicing and don't care all the wires you need are also at the rear defogger switch, right nect to where I put the meter. I just didn't want to splice into it when I could do my soldering indoors instead.Steve said:Hey, I bought one of those but I am kinda dumb. Which wires/parts should I wire it to?