For Toyota vehicles that were not engineered to have factory keyless entry systems on every model, Toyota often adds a port-installed or dealer-installed keyless entry system here in North America. One of these systems uses a 3-button remote keyfob with FCC ID ELVATDC on the back. This remote has lock and unlock buttons on the front and a panic button on the back. As you might guess from the lack of a rear button function, this dealer-installed system was generally added to Toyota trucks, such as Tacoma and Tundra models.
See Toyota add-on keyless entry system remote with FCC ID ELVATDC at this link.
The circuit board in this remote is identical to the one in a 4-button remote with FCC ID ELVATDD. Because the board is the same, the two remotes are interchangeable. Remotes Unlimited sells the 4-button version to replace both the 3-button and 4-button keyfobs. As may be obvious, if your vehicle has a system installed that did not operate a rear function, the rear function button on the 4-button remote will not do anything.
Both remotes are programmable by a user.