We have 2 garage doors with openers, but they are of different ages and both use a different frequency door opener. Since we have an entrance to the house from the garage I didn't feel comfortable keeping the "clip onto your visor" style opener in the Jeep.
If you only have modern doors by craftsman/chamberlain/liftmaster, you may consider using a keychain remote. I have one, but it won't work with the door on the side of the garage I park on. otherwise, It's probably a better idea than this mod. I think mine was $35 3 years ago.
I was in a junkyard looking for an outside temperature sensor for my rear view mirror and I found a homelink module in a 5th generation Nissan Maxima sun visor. I also found an Infinity model from the same era that used the exact same visor, so I grabbed both figuring one homelink will go in the jeep and one will go in my girlfriend's car. The sensor and 2 visors ended up costing me $20 cash. I figured I got a good deal.
older homelink modules don't work with what are called "rolling code" openers. Most modern garage door openers use rolling codes so you'll probably want to find a module out of a 1999+ vehicle. The rolling code compatable units will have the house with an arrow icon on them.
This is what the visor looked like
The first order of business was to rip and pry apart the visor to get at the homelink module. I took the whole thing apart to salvage as much wire as possible. I kept the lighted vanity mirror too, but that's only because I'm a pack rat.
The face plate of the module clips onto the body of the module and sandwiches the black button pad and the fabric of the visor in between. You can seperat them using a small screwdriver or other flat pointy object to push the clips apart that hold them together.
Rubbing alcohol worked very well at removing the junkyard grime from the faceplate.
Here you can see the clips that need to be seperated.
I opened up the module by pressing in the two tabs on the left side. I noticed that the PCB was already drilled for permanent wires so I decided to ditch the plug and soldered the wires directly to the circuit board. This allowed me to shave 1/2" off the module which allowed for slightly easier placement. I also removed about 1/4" of the PCB using a cut off wheel on my dremel. The portion I cut off is the part that the plug slipped over.
I then crimped on some disconnects and tested it in my jeep to make sure that it worked when mounted down low. The range isn't quite as good as when it's mounted in a visor but I found it acceptable.
The soldering is ugly but it's a solid connection. There were pads on both sides so I soldered it on both sides as well. I think I need to get solder with less flux in it.
Once I confirmed it would work, I took a deep breath and prepared to cut holes in my interior panels.
Using the old fabric as a guild, I traced the holes onto the console using a gold marker.
I then drilled out tthe holes using a step bit/unitbit.
I then tried to clip the unit back together. It wouldn't work.
The plastic console is too thick to allow the homelink module to clip together.
My solution was to pop a sanding drum into my dremel and thin out the inside of the console. It's ugly, but nobody sees it.
While the photos may not show it very well, I probbably removed half of the thickness of the panel. It took a bunch of trial and error but I finally got it to make a solid connection. Once you line it up you can just snap the faceplate on.
I ended up shaving a bit more off the homelink module while making it fit. I also added hot melt glue to the power leads to insulate them.
Once that was done I connected the power to a line I tapped into the back of the ignition-switched 12v outlet. I intentionally did this so that the homelink will only work while my keys are in the ignition. This way the only way people can use it to break into my house is to screwdriver my ignition. I feel this is just as safe as the ones in my parents cars, and breaking a window is probably easier than turning my ignition or ripping the unit out and connecting it to a battery.
The unit does not require power to store the opener information, but it does require power to transmit. It works out quite well in this application.
I'm currently painting the second faceplate I had black to see how I like it compared to the beige. More pictures will follow.
Here's the instructions for programming the homelink to a craftsman garage door opener.