programming the garage door remote mirror WITHOUT an existing remote
I have the rear view mirror that has the garage door remote opener thing in it. I have a sommer marathon 800 door opener, but no remote for it as the previous tennant did not leave one for me when I moved in. The door opens fine with a wall switch, but I can't get the car remote to open it. I can't program it with a remote therefore in the usual way.
Is it possible to teach the car to open it or do I have to get a remote programmed first?