A method is provided for detecting the broadcasting of a RF message from a remote transmitter to an in-vehicle receiver. The RF message includes an initial preamble having a plurality of pulses. Power is provided to the receiver for a first predetermined period of time. The preamble pulses received are counted. A determination is made whether the number of preamble pulses received is between a first and second predetermined number of preamble pulses. If the number of preamble pulses is greater than the first predetermined number of preamble pulses, then power is provided to the receiver for processing the RF message. If the number of preamble pulses is less than the second predetermined number of preamble pulses, then power is terminated to the receiver. If the number of preamble pulses are between the first and second predetermined number of preamble pulses, then power is extended to the receiver for an extended period of time.