Originally Posted by chet24
So I'm attempting to do this for an 08, I realize this thread has been beat to crap by dumb people who don't read and hope I don't come across as that. I want to buy the ECM, from an 05-09 legacy and then I have to get an extra key for each key I want, because none of my current ones will work, right? So two keys will put me back $200+? Is there an easier way to do this?
You don't need new keys, they will still work, remember you are only replacing the remote keyless function here.
The absolutely cheapest way to do this is get the legacy keyless, one used legacy key, a new housing/blade, and one used old legacy teardrop fob. Swap the keyless units, make your all in one key by hacking the valet key for the transponder, and program the old used legacy teardrop for use with the other stock keys. When done you now have one cool key, a remote and key set, and a spare key. You could even sell your impress keyless unit and remotes on eBay..