The ride did not use wireless transmission. It used a bus bar that followed the length of the track in certain areas to provide power and to relay a signal back to the PLC. The train had "fingers" on certain cars, including the lead car that made contact with the bus bar. The grey rails on either side of the track, and most of the fingers were removed when the ride was moved to KI, as well as the onboard motor that could raise or lower the car. It still has the smaller locking pin motors on board, however.
You can see the "fingers" sticking out in this shot.
One more bonus photo, as far as I know this is the only existing photo of a train leaving with the cars in the upright position, dated May 2002.
But back to the wireless, Firehawk still uses the same bus bar method in the station(not wireless), albeit far fewer contacts are needed. You can just barely make out the contact pins to the right of the white nylon wheel on the left side of coach 1.