This is what I had before, with a broken voltmeter and using a piece of wire in place of the rear defog switch: Remove dash piece: Wiring diagram of connector for defog switch: This would be a good time to add a voltmeter if you do not already have one. Everything you need is right there, but the +12V is only there with the ignition on (unlike the radio circuit where it is on with the Accessory position as well). But since it's already there, if you want to add that as well, it would be easier to just go ahead and do that now. I already have my voltmeter going to my radio circuit, and am not covering that here. I am only pointing out here that even if you don't have a Factory Service manual or wiring diagram, it should be pretty obvious that the rear defog is the thicker wires in the middle: There was a spot where I had to grind down the inside of the dash piece. I probably should have rotated this picture 180 degrees. I show that here: This is the switch that I chose to use. It's a lighted 30A rocker switch. The red paint is the positive, the middle, the output, and the remaining one is the ground, only necessary if you want the light part to work (recommended). Note that this is on a 20A circuit. I only bought the 30A switch instead because I liked it better. Use whatever switch you like. This switch is smaller than the hole in the dash used by the OE switch, and uses a standard 1/2" hole to mount in (which is kind of a standard, meaning if this one breaks, it will be easy enough to replace). So make an adapter plate. 3" x 1.25" with the appropriate holes drilled in it for the switch and hardware to mount it to the dash: The plate was made used to be the front cover of a washing machine. Painted flat black. You won't see the edges, so it doesn't have to be pretty. With the switch installed: Mounted to the dash piece: I used and recommend locknuts to keep the screws from coming loose. If I had the time and inclination to go to the hardware store just for this, I would have bought dark colored screws. Make some wiring harness pieces to plug into the switch and wiring harness: Note that the ends are different, but basically all the same except for the color, and the ground wire (black) can be a thinner piece of wire (whatever you happen to have laying around). I used a white wire for the switch output. The red and white wire are #12 stranded, the same type I would use in conduit in my house. Plus these into the switch: Install into dash and plug into wiring harness connector: I wrapped this with a lot of electrical tape!!! Otherwise you risk it coming apart. Install dash piece. with rear defog off: With rear defog on: Light is much brighter than the OE one (which I like). Note that this new voltmeter consistently reads anywhere from .2 - .5 volts higher from every other voltmeter I own (including an expensive Fluke meter). But the relative drop in voltage indicates that the rear defogger is probably working. Also note that my previous various measurements indicates that the current draw from the rear defogger varies with temperature (the colder, the more amps it draws) so I would expect the voltage drop to be higher on a colder day (it was not particularly cold when I did this, maybe mid 50's). I do not recommend the Dragon gauge that I used here. It's really cheap and it shows. It's in a cheap plastic case, the bolts in the back are small and cheap, and the threads almost stripped out when I tried to use them. It was also slightly larger then the gauge it replaced (also very annoying since that made the install take more time). Only thing I like about this new voltmeter is that the digital readout is way easier to read than my previuos analog model, and it very visible in day and night conditions.