Abstract: For use in conjunction with an existing wireless transmitter/receiver, a transmitter provided by the invention preferably uses some or all of the same codes as the existing remote transmitter to perform a desired function such as door or trunk unlocking, windows, light activation, and so forth. One embodiment of the invention includes a passive entry system so that only an authorized operator can use the device. In a preferred embodiment, a user carries a wallet-sized card or other device, such that upon activation of the keypad associated with the inventive transmitter, a signal is first sent to the user for verification. If the card or other device carried by the user properly transponds an appropriate authorization signal, the inventive transmitter broadcasts the codes appropriate to the function being requested. Alternatively, biometric information such a fingerprint or voiceprint may be used.