You can use any SPDT relay as long as it works on 12V. I also used a relay that I previously recovered from an old alarm module so is not necessary to buy a new one. I see you already posted on that thread, just wait for an answer or you can contact the user borlax via private message as he will get a notification on his e-mail.He is the one who can provide more info :twoup: . I didn't have the pinouts for the E39 master door module nor GM module, that's why I hacked into the door module and that's why I solder the wires directly on the board.You can chose not to do that if you know the exact pinouts of the master module, ( like they show for E46 in the link above). Sorry, this is the closest I have.Save the picture and zoom on it, you will see exactly where to solder the wires. ps: don't solder the wires on this side of the board!You will have to solder the wires on the other side.Contacts from this side of the board corresponds with contacts on the other side, just be shure you solder in the right place. http://img717.imageshack.us/img717/352/picture308a.jpg Yes, you can use it.