Patent ID: 8571725

Claim:
An apparatus for locating a vehicle electronic key for a vehicle, the apparatus comprising: a fob for receiving a low frequency signal, determining a low frequency signal strength value of the received low frequency signal, and providing a radio frequency response signal, a portion of the response signal including the determined low frequency signal strength value; a low frequency antenna located at or near a central location of a cabin of the vehicle for providing the low frequency signal substantially throughout and substantially within the cabin of the vehicle; a controller for receiving the radio frequency response signal from the fob, comparing the determined low frequency signal strength value against a predetermined threshold, and determining if the fob is inside the cabin of the vehicle based on the comparison; and a vehicle engine immobilizer responsive to said controller, said controller controlling said immobilizer in response to said comparison; wherein said controller includes a prestored low frequency energy map and wherein said controller makes said determination if the fob is inside the cabin of the vehicle by comparing the determined low frequency signal strength signal value against the prestored low frequency energy map.